soft scorpionate anions as platforms for novel heterocycles
TRANSCRIPT
DOI: 10.1002/chem.201300091
Soft Scorpionate Anions as Platforms for Novel Heterocycles
Rajeev Rajasekharan-Nair,[a] Annemarie Marckwordt,[a] Samuel T. Lutta,[b]
Matthias Schwalbe,[a] Anne Biernat,[a] David R. Armstrong,[a] Allan J. B. Watson,[a]
Alan R. Kennedy,[a] John Reglinski,*[a] and Mark D. Spicer*[a]
Introduction
Stable compounds of the hydrotris(thioimidazolyl)borateanions ([TmR]� , R=Me, Ph, etc.) have been isolated for themajority of the elements within the periodic table(Figure 1).[1] Within this large catalogue of compounds are
species which utilise Mn(CO)5 and AuPR3 fragments;[1–7]
fragments that are iso-lobal with alkyl groups. These reportssuggested that it should be possible to extend the chemistryof [TmR]� , and indeed we have been able to generate cati-onic tris-alkyl adducts of the soft scorpionates ([TmMeSE]2+ ,where E= Me, allyl, Bz, Figure 1).[8]
The analysis of these species indicated a preference forconformations in which pairs of thiones (in [TmMe]�) andthioethers (in [TmMeSE]2+), respectively, lie parallel to theB�H moiety.[8] This observation suggests that [TmMe]� willbe predisposed to the formation of polycyclic rings whentreated with dihaloalkanes. Indeed, on the prolonged treat-ment of [TmMe]� with CH2Cl2 Crossley et al. isolated bis(1-methyl-imidazol-2-yl-thio)-methane-N,N’)-(1-methyl-2-thioi-midazol-3-yl)borane (2 a), that is, a species in which the twothiones are connected by a bridging methylene group.[9]
Using more appropriate halo-alkanes we have been ableto increase the efficiency of this reaction and extend thisseries of multi-ring macrocyclic compounds (Figure 2). Fur-thermore, the introduction of oxidising electrophiles (NO+,I+) has resulted in a remarkable intramolecular ring closure,which leads to the formation of unprecedented heterocyclicspecies.
Keywords: alkylation · iodine · ringclosure · nitrosation · soft scorpio-nates
Abstract: Soft scorpionates have thus far been seen mainly as a family of ligands.Their chemistry is extended here to the production of novel cationic macrocyclesusing dihaloalkanes. By replacing the dihaloalkanes with mild oxidising agents(NO+ , I2) we obtain two unique polycyclic heterocycles. The mechanism whichleads to the formation of these polycyclic heterocycles is investigated using abinitio DFT calculations.
[a] Dr. R. Rajasekharan-Nair, A. Marckwordt, Dr. M. Schwalbe,A. Biernat, Dr. D. R. Armstrong, Dr. A. J. B. Watson,Dr. A. R. Kennedy, Dr. J. Reglinski, Dr. M. D. SpicerWestCHEM Department of Pure and Applied ChemistryUniversity of Strathclyde, 295 Cathedral St. , Glasgow G1 1XL (UK)E-mail : [email protected]
[b] Dr. S. T. LuttaDepartment of Chemistry and BiochemistryChepkoilel University College, Moi UniversityP.O. Box 1125, Eldoret (Kenya)
Supporting information for this article is available on the WWWunder http://dx.doi.org/10.1002/chem.201300091.
Figure 1. The TmR anion and the [TmRSE]2+ dication.
Figure 2. The reaction of NaTmR with 1,n-dihaloalkanes (n=1, 3–6, 8,10); mt =methimazolyl.
Chem. Eur. J. 2013, 00, 0 – 0 � 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
These are not the final page numbers! ��&1&
FULL PAPER
Results and Discussion
The treatment of NaTmR with a range of a,w-dihaloalkanes(X ACHTUNGTRENNUNG(CH2)nX: R= Me; X=Br, I: n= 3-6, 8, 10 and R= Ph;X= I; n= 3; Figure 2) leads to the remarkably facile forma-tion of monocationic, fused tricyclic species (2 b–g, 3 a,b)centred on 10–17 membered macrocyclic rings.
A selection of these were subjected to analysis by singlecrystal X-ray diffraction (Figure 3). Despite the increasing
macrocyclic ring size the species all adopt a similar confor-mation in which all three thioethers remain above the BN3
plane. Little strain is transferred into the BN3 fragment withthe B�N distances (1.553–1.610 �) and the aN-B-N angles(108.7–109.78) occurring within a very small range. Theimaginary torsion angle S2-N3-N1-S1 describes the influenceof the increasing ring size on the relative twist of the alkylat-ed methimazolyl rings with respect to one another. Thesechange in a non-uniform manner with largest and smallestrings returning the larger values (Figure 3). The specieswhich did not crystallise sufficiently well for X-ray diffrac-tion were characterised by mass spectrometry and 1H NMRspectroscopy. Mass spectrometry demonstrates that thesespecies are discrete cations. The 1H NMR spectroscopy, byvirtue of the downfield shift in the heterocycle C�H reso-nances, confirms the modification of two of the three methi-mazole rings.
The ability to generate even the very large fifteen andseventeen-membered rings suggests that the cyclisationprocess is pre-organised. Ab initio analysis of [TmMe]� and[TmPh]� shows that the anions have a preference for a motif(2:1, Figure 4) where the rings adopt conformations in
which two of the thione sulfur atoms lie adjacent to the B�H unit, and one is twisted away.[8] A preference for thesecompact conformations makes intramolecular cyclisationpreferable over intermolecular coupling.
The alkylated compounds discussed above all formthrough reactions of NaTmR with electrophiles capable offorming stable bonds to sulfur. Reactions with electrophilicspecies, such as NO+, which do not form stable adducts,have also been reported.[10] In these contrasting studies wewere able to isolate a DMF adduct of tris(thioimidazolyl)-borane which results from borohydride oxidation.[10] Howev-er, from this reaction we were also able to isolate a secondproduct, the remarkable, and hitherto unreported neutralheterocycle, 4, in low yield (Figure 5 and Figure 6). This was
believed to result from nitrosation of the thione followed byring closure to an adjacent methimazole, with formal loss ofHNO. Replacing NO+ with a milder oxidant, namely I2, weare able to increase the yield of this novel species and pro-vide a rational synthesis of the heterocycle 4. In addition tothe structural characterisation, spectroscopic evidence sup-ports the formulation. The 1H NMR spectrum highlights theloss of symmetry of the parent, showing three inequivalentmethyl resonances and four doublets and a singlet for the
Figure 3. X-ray crystal structure of 2 d. The corresponding structures of2b, 2 c and 2 f can be found in the Supporting Information. Compound2a has been reported previously by Crossley et al.[9] The thermal ellip-soids are drawn at the 50 % level. The imaginary S2-N3-N1-S1 torsionangles for the series of heterocyclic rings are: 2a (n =1) 65.78, 2 b (n=3)58.88, 2 c (n= 4) 29.38, 2d (n=5) 11.98, 2 f (n =8) 98.58.
Figure 4. A schematic representation of the four conformations of[TmR]� . The 2:1 conformation is preferred by both anions (R =Me,Ph);[5] see also the Supporting Information. Yellow= sulfur, red =boron,blue=H.
Figure 5. Synthesis of fused heterocycles from NaTmR. Conditions: a) I2
or NOBF4; b) I2 or NOBF4; c) PI3.
www.chemeurj.org � 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Chem. Eur. J. 0000, 00, 0 – 0
�� These are not the final page numbers!&2&
imidazole protons (in contrast to the single methyl reso-nance and two doublets for the imidazole protons in theparent compound). The high resolution mass spectrumshows a positive ion at m/z 351.0686, equivalent to [M+ H]+,whereas the parent shows a negative ion at this mass.
Surprisingly, the corresponding reaction of the [TmPh]�
anion with NO+ or I2 did not lead to the formation of anisostructural heterocycle. The mass spectrum of the product(m/z 505.1435) clearly suggested that a single sulfur atomhad been extruded from the starting anion. Protracted ef-forts to crystallise and structurally characterise this materialfailed. However, during our concurrent studies of the reac-tion of NaTmPh with PI3 we obtained an intriguing product,which was instructive in the characterisation of this species(Figure 7). This reaction also leads to desulfurisation of the[TmPh]� anion, with ring closure through the adjacent thio-nes to form a second borate-centred heterocycle (Figure 7,6). Iodine and the triiodide anion presumably arise from de-composition of PI3. The former forms a stable cationicadduct through the thione of the unmodified methimazolering, whereas the latter is simply the counter anion. Compar-ison of the spectroscopic data from the products of the tworeactions supports the notion that the cation of 5 is thecommon product of both. Most compelling are the massspectra, in both cases dominated by a peak at m/z 505.1432.Due to the weakness of the S�I2 interaction it is unsurpris-
ing that the mass spectrum of 6 is dominated by the molecu-lar ion of the cation of 5. Furthermore, the 1H NMR spec-trum in both cases shows a pair of doublets at high frequen-cy due to the protons on the new heterocycle and a pair ofdoublets at lower frequency arising from the “free” methi-mazole (in a 2:1 ratio). The low frequency doublets in 6 areshifted relative to those in 5, presumably due to the forma-tion of the I2 adduct. The phenyl protons are less well de-fined, but nevertheless integrate correctly (see the Support-ing Information).
Iodine adducts of thiones are well known.[11–14] These aregenerally divided into three categories: A, S�I+ I� (d [�],I�I>2.8); B, S�I�I (d [�], I�I~2.6–2.8 �); and C, S···I�I(d [�], I�I<2.6 �), where compounds are assigned to acategory based on their corresponding S�I and I2 bondlengths. The compound reported above is cationic and al-though its bond lengths place it at the boundary betweentype A and B, when one considers the influence of thecharge derived from the heterocyclic ring a formulation ofS�I+ is more appropriate.
The nature of the bonding in the cation of 6 is instructivein understanding the formation of 4 and 5. Initially the elec-trophile forms a type A adduct at sulfur. For simple neutralthiones these adducts of iodine can be stable.[11–14] In con-trast, the S-nitrosation of thiones generates a reactive entity,which leads to S�S coupling.[15] In the present case S�S cou-
Figure 6. X-ray crystal structure of the heterocyclic product 4 derivedfrom the oxidation of NaTmMe. Note the presence of the three sulfuratoms. Thermal ellipsoids are drawn at the 50% level.
Figure 7. X-ray crystal structure of 6. Note the loss of sulfur (Figure 4). I2
and I3� are also oxidation products. I3
� is omitted for clarity. Bondlengths [�]: S(1)�I(1)= 2.641(2); I(1)�I(2) =2.9213(8). Bond angle [o]:S(1)-I(1)-I(2) =175.01(5). Thermal ellipsoids are drawn at the 50 % level.
Chem. Eur. J. 2013, 00, 0 – 0 � 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.chemeurj.org
These are not the final page numbers! ��&3&
FULL PAPERSoft Scorpionate Anions
pling would lead to an unfavourable 7-membered ring,which DFT calculations show to be unstable; we, therefore,have not considered this mechanism further. On the otherhand, the intramolecular ring closure with the heterocycleskeleton in the 1- or 5-position leads to a planar 6-mem-bered ring and an extensively delocalised tricyclic heterocy-
cle (Figure 8). Although this is not a common reaction forneutral thiones a related ring closure has been reported be-tween thioimidazole and imidazoles.[16] That the two anions[TmMe]� and [TmPh]� form different heterocycles is more dif-ficult to explain. Studies on the conformations and dynamicbehaviour of the [TmR]� anions indicate that there are fourconformations of the uncoordinated anion (Figure 4; see theSupporting Information).[8] DFT analysis of these indicatethat the most favoured species for both has the anion in aconformation that aligns two thiones with the borohydridegroup with the remaining thione lying below the plane de-fined by the three nitrogen atoms bonded to boron (2:1,Figure 4). Thus, there is no preference for either reactionbased on the conformation of the anions themselves. Ananalysis of the charges (Table 1, Mulliken populations) onthe atoms in the thio-imidazole rings indicates that the sub-stituents on the nitrogen atoms have a minimal effect onelectronic character of the parent scorpionate anions. This isnot surprising as the phenyl group does not adopt a confor-mation co-planar with the thio-imidazole ring in either theDFT analysis of the anion (see the Supporting Information)or any of its reported X-ray crystal structures.[17–19] DFTanalysis of the charges on the atoms as a result of the alkyla-tion of a single thione (Figure 1, Table 1) demonstrate theexpected change occurring at sulfur as the thione changes toa thioether. The calculated charges on the thioimidazolerings lying below the BN3 plane remain similar despite alky-lation, suggesting that these rings are the spectators in thering closure reaction. Crucially, however, we observe that inthe rings lying co-planar with the B�H the calculated charg-es on C3 (Figure 1, Table 1) show the biggest difference be-tween the two species. The obvious ring closure mechanismfollows enamine chemistry where C3 acts as the nucleo-phile.[20–22] By virtue of the low charge at this atom (Table 1)this pathway is available to [TmMe]� (Figure 8, left). Howev-er, for [TmPh]� the charge calculated on C3 is higher (+0.13) and consequently ring closure between C3 and thethione is no longer favourable. Instead ring closure occursby the reaction of a thione on the carbon adjacent to the al-kylated sulfur atom, that is, nucleophilic attack onto the imi-nium ion followed by subsequent elimination of a thiolate(Figure 8, right).
Table 1. The charges (Mulliken population) on the thioimidazole rings of [TmMe]� , [TmPh]� and their monomethylated adducts 7 and 8 (Figure 9; seealso the Supporting Information).[a]ACHTUNGTRENNUNG[TmMe]� 7 ACHTUNGTRENNUNG[TmPh]� 8
ring A (Me) ring B (U) ring C (D) ring A (Me) ring B (U) ring C (D)
hydride �0.04 �0.06 �0.04 �0.06boron + 0.49 +0.47 +0.50 +0.46S �0.43, �0.43, �0.40 + 0.11 �0.39 �0.39 �0.39, �0.40, �0.43 +0.13 �0.36 �0.36N1 �0.35, �0.35, �0.38 �0.30 �0.37 �0.36 �0.35, �0.38, �0.35 �0.29 �0.37 �0.36N2 �0.34, �0.35, �0.34 �0.32 �0.34 �0.34 �0.41, �0.34, �0.35 �0.35 �0.41 �0.41C1 +0.20, + 0.22, +0.18 + 0.18 +0.20 +0.16 +0.18, +0.20, +0.18 +0.18 +0.18 +0.15C2 �0.01, �0.01, �0.03 + 0.02 �0.01 0.00 �0.02, �0.01, �0.03 +0.02 �0.01 +0.01C3 +0.03, + 0.04, 0.00 + 0.02 0.00 0.00 +0.04, +0.04, +0.00 +0.08 +0.13 0.00
[a] The atom numbering system follows that shown in Figure 1. The three imidazole rings are identified as A, B and C in the calculations (see the Sup-porting Information). Ring A is by definition the site of methylation, ring B is the ring which remains above the BN3 plane and ring C is the ring whichlies below the BN3 plane (conformation 2:1, Figure 4)
Figure 8. A schematic representation of the scorpionate ring closure reac-tions. Left: with [TmMe]� where the attack of the methimazole ring onthe thione sulfur is preferred. Right: with [TmPh]� where attack of thionesulfur on thione carbon, with desulfurization, occurs.
www.chemeurj.org � 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Chem. Eur. J. 0000, 00, 0 – 0
�� These are not the final page numbers!&4&
J. Reglinski, M. D. Spicer et al.
The DFT derived molecular orbitals also hint at the dif-ferences between the two monomethylated (7, 8 ; R=Me,Ph) species (Figure 9). The HOMO, in both cases, is a p-or-
bital on the non-alkylated ring with significant componentson both the ring atoms and on sulfur. The LUMOs, althoughsimilar to one another in some respects, also reveal somedifferences. Both are located on the alkylated ring, but inthe case in which R= Me, there is a significant localisationon the alkylated sulfur atom, whereas in the case in whichR=Ph the LUMO also encompasses orbitals on the phenylp-system, and the component on sulfur is now minimal.Consequently, although nucleophilic attack from theHOMO to the sulfur atom is possible in the methyl substi-tuted case, in the phenyl substituted system attack on C1 ispreferred. These observations are consistent with 4 beingabsent in the reaction mixtures derived from [TmPh]� . How-ever, it does not explain why 5 is absent in the reactions of[TmMe]� . Greater clarity regarding the ring closure mecha-nisms will only become available as new species are report-ed.
Conclusion
In conclusion, the observations described here extend thechemistry of the soft scorpionates to that of novel cationsand unique polycyclic heterocycles. The study reinforces theview that minor changes in the substituents on the nitrogen(Me, Ph) in the methimazolyl unit will give rise to differentchemistry. This diversity is expected to continue as new het-erocycles are introduced into the soft scorpionate cataloguemaking each anion worthy of study in its own right.
Experimental Section
Unless otherwise stated all chemicals were commercially obtained andused without further purification. NaTmMe and NaTmPh were prepared aspreviously reported.[23, 24] All NMR spectra were recorded on either aBruker DPX400 or Bruker AV500. The spectra were referenced to inter-nal solvent peaks and thus to TMS. Infrared spectra were recorded asKBr discs using a Nicolet Avatar 360 FT-IR spectrometer. Mass spectrawere recorded using a Thermo Finnigan LCQDuo by electrospray iontrap and a Thermo scientific LTQ orbitrap for accurate mass. Crystalswere coated in mineral oil and mounted on glass fibres. Data were col-lected at 123 K on an Oxford Instruments CCD diffractometer usinggraphite monochromated MoKa radiation. The heavy atom positions weredetermined by Patterson methods and the remaining atoms located inthe difference electron density maps. Full matrix least squares refinementwas based on F2 with all nonhydrogen atoms anisotropic. Although thehydrogen atoms were mostly observed in the difference maps, they wereplaced in calculated positions riding on the parent atoms. The structuresolution and refinement used the programs SHELX-97[25] or SIR 92[26]
and the graphical interface WinGX.[27] A summary of the crystallographicparameters are given in Table 2.
The reactions of NaTmMe with dihaloalkanes : A suspension of NaTmMe
(0.187 g, 50 mmol) in chloroform (20 mL) was refluxed, overnight, with1 mol equivalent of the relevant dihaloalkane. The mixture obtained wasfiltered to remove the sodium halide and then taken to dryness. The re-sulting solid mass was purified as described below.
1,3-Diiodopropane : Recrystallised from methanol: n-hexane by vapourdiffusion. Yield =29%. 1H NMR (500 MHz, CDCl3): d=7.62 (s, 2H,-CH), 7.37 (s, 2 H, -CH), 6.8 (s, 1 H, �CH), 6.75 (s,1H, �CH), 4.08 (s, 6 H,�CH3), 3.57 (s, 3 H, �CH3), 3.42 (m, 2 H, HCH) 3.37 (m, 2H, HCH) 2.38(s, 1 H, HCH), 1.94 ppm (s, 1 H, �HCH); 13C NMR (125 MHz, CDCl3):d=164.8, 142.1, 126.1, 121.0, 19.9, 35.9, 34.4, 34.2, 30.6 ppm; FT-IR(KBr): v =2505 (nB-H), 740 cm�1 (nC-S); ESI-MS [TmS,Sprop]+ : accuratemass predicted 393.11556, found 393.11526; elemental analysis calcd (%)for C15H22N6BS3I: C 34.64, H 4.23, N 16.16; found: C 34.01, H 3.99, N15.41.
1,4-Dibromobutane : Recrystallised from methanol: diethyl-ether byvapour diffusion. Yield=35 %. 1H NMR (500 MHz, CDCl3): d =8.02 (d,2H, -CH), 7.59 (d, 2 H, �CH), 6.76 (d, 1H, �CH), 6.65 (d, 1H, �CH), 4.1(s, 6H, �CH3), 3.52 (s, 3 H, �CH3), 3.15 (m, 2 H, HCH), 2.99 (m, 2H,HCH), 2.15 (m, 2H, �HCH), 1.43 ppm (m, 2 H, �HCH); 13C NMR(125 MHz, CDCl3): d=164.5, 142.5, 127.4, 125.2, 120.8, 119.1, 36.5, 35.8,34.7, 27.1 ppm; FT-IR (KBr): v=2565 (nB-H), 745 cm�1 (nC-S); ESI-MS[TmS,Sbut]+ : accurate mass predicted, 407.13121, found 407.13147; ele-mental analysis calcd (%) for C16H24N6BS3I·H2O: C 38.02, H 5.19, N16.64; found: C 38.29, H 4.97, N 17.05.
1,5-Diiodopentane : Recrystallised from methanol: diethyl-ether. Yield=
25%. 1H NMR (500 MHz, CDCl3): d= 7.87 (d, 2H, �CH), 7.62 (d, 2H, �CH), 6.70 (d, 1H, �CH), 6.35 (d, 1H, �CH), 4.11 (s, 6 H, �CH3), 3.54 (s,3H, �CH3), 3.17 (m, 2H, HCH), 3.07 (m, 2H, HCH), 2.31 (m, 1H,HCH) 1.88 (m, 2H, HCH), 1.72 (m, 1H, HCH), 1.55 ppm (m, 2H,HCH); 13C NMR (125 MHz, CDCl3): d=165.0, 142.0, 127.0, 125.0, 120.3,119, 36.9, 37.1, 35.0, 29.8, 25.6 ppm; FT-IR (KBr): v =2540 (nB-H),
Figure 9. Calculated molecular orbitals (DFT derived iso-surfaces) formonoalkylated TmR (R=Me, Ph). From left to right: 7, HOMO; 7,LUMO; 8, HOMO; 8, LUMO. Alternative views of the LUMOs of 7and 8 can be found in the Supporting Information.
Chem. Eur. J. 2013, 00, 0 – 0 � 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.chemeurj.org
These are not the final page numbers! ��&5&
FULL PAPERSoft Scorpionate Anions
745 cm�1 (nC-S); ESI-MS [TmS,S’pentyl]+ : accurate mass predicted,421.14686, found 421.14719; elemental analysis calcd (%) forC17H26N6BS3I·2H2O: C 34.93, H 5.18, N 14.25; found: C 35.39, H 4.92, N14.25.
1,6-Diiodohexane : Recrystallised from methanol: diethyl-ether. Yield=
30%. 1H NMR (500 MHz, CDCl3): d= 7.61 (d, 2H, �CH), 7.59 (d, 2H, �CH), 6.72 (d, 1H, �CH), 6.42 (d, 1H, �CH), 4.04 (s, 6H, �CH3), 3.5 (s,3H, �CH3), 3.40 (m, 2H, HCH), 2.95 (m, 2H, HCH), 1.81 (m, 2H,HCH), 1.69 (m, 2 H, �HCH), 1.55 (m, 2H, �HCH), 1.33 ppm (m, 2H, �HCH); 13C NMR (125 MHz, CDCl3): d=164.8, 142.1, 127.1, 125.0, 120.8,119.0, 36.9, 35.5, 34.4, 27.2, 23.9 ppm; FT-IR (KBr): v =2515 (nB-H),740 cm�1 (nC-S); ESI-MS [TmS,Shexyl]+ : accurate mass predicted435.16251, found 435.16272; elemental analysis calcd (%) forC18H28N6BS3I·3H2O: C 35.06, H 5.56, N 13.64; found: C 35.47, H 4.82, N13.01.
1,8-Diiodooctane : Recrystallised from methanol: diethyl-ether. Yield=
32%. 1H NMR (500 MHz, CDCl3): d= 7.65 (d, 2H, �CH), 7.53 (d, 2H, �CH), 6.73 (d, 1H, �CH), 6.51 (d, 1H, �CH), 4.03 (s, 6 H, �CH3), 3.56 (s,3H, �CH3), 3.40 (m 2H, �HCH), 2.84 (m, 2H, �HCH), 1.18 (m, 2H, �HCH), 1.60 (m, 4 H, �HCH), 1.46 (br, 4H, �HCH), 1.25 ppm (m, 2H, �HCH); 13C NMR (125 MHz, CDCl3): d=164.6, 141.7, 126.9, 125.3, 120.6,119.2, 36.7, 35.2, 34.6, 27.4, 25.7, 25.0 ppm; FT-IR (KBr): v=2535 (nB-H), 745 cm�1 (nC-S); ESI-MS [TmS,S’octyl]+ : accurate mass predicted463.19381, found 463.19424; elemental analysis calcd (%) forC20H32N6BS3I: C 40.69, H 5.46, N 14.23; found: C 40.27, H 5.39, N 13.90.
1,10-Diiododecane : Recrystallised from methanol: diethyl-ether. Yield=
27%. 1H NMR (500 MHz, CDCl3): d= 7.62 (d, 2H, �CH), 7.46 (d, 2H, �CH), 6.75 (d, 1H, �CH), 6.49 (d, 1H, �CH), 4.2 (s, 6H, �CH3), 3.55 (s,3H, �CH3), 3.21 (m, 2H, HCH), 2.96 (m, 2H, HCH), 1.75–1.56 (m, 5 H,HCH), 1.52–1.41 (m, 5H, HCH), 1.41–1.23 ppm (m, 6 H, HCH);13C NMR (125 MHz, CDCl3): d =164.8, 142.2, 126.3, 125.4, 120.2, 119.3,36.7, 36.1, 34.7, 28.6, 26.3, 26.0, 15.3 ppm; FT-IR (KBr): v=2520 (nB-H),755 cm�1 (n C-S); ESI-MS [TmS,S’decyl]+ : accurate mass predicted491.22565, found 491.22511; elemental analysis calcd (%) forC22H36N6BS3I·H2O: C 41.50, H 6.02, N 13.21; found: C 41.68, H 5.75, N12.64.
The treatment of NaTmPh with 1,3-diiodopropane : NaTmPh (0.14 g,0.25 mmol) in chloroform (20 mL) was refluxed for 2 h with 1,3-diiodo-propane (0.07 mL, 0.24 mmol). The white precipitate formed was filteredoff and the solution was taken to dryness. The product was recrystallisedby the slow vapour diffusion of a solution of the compound in methanol
with diethyl ether. 1H NMR (400 MHz, DMSO): d=8.14 (d, 2H, �CH),7.77 (d, 2H, �CH), 7.69–7.64 (br m, 14H, Ar), 7.49 (t, 2 H, �CH (Ar)),7.46 (d, 1 H, �CH), 7.42 (t, 1H, Ar), 7.16 (d, 1 H, �CH), 2.66 (m, 2H,HCH), 2.31 (m, 2H, HCH), 1.79 (m, 1H, HCH), 1.39 ppm (m, 1H,HCH); 13C NMR (100 MHz, DMSO): d=164.6, 143.1, 142.7, 138.1, 135.3,130.7, 129.9, 128.7, 127.6, 126.2, 125.5, 122.8, 119.7, 64.9, 33.5, 29.9 ppm;FT-IR (KBr): v= 2465 (B-H), 760 (C=S), 740 cm�1 (C-S); ESI-MS[TmPhSS’propyl]+ : accurate mass predicted 579.1625, found 579.1621; ele-mental analysis calcd (%) for C30H28N6BS3I·3 H2O: C 47.36, H 4.51, N11.05; found: C 47.06, H 4.07, N 10.66.
Treatment of NaTmMe with nitrosonium tetrafluoroborate (NOBF4): Asolution of NaTmMe (0.37 g, 1 mmol) in DMF was mixed with nitrosoni-um tetrafluoroborate (0.12 g, 1 mmol) under a blanket of nitrogen gas. Amarked colour change (colourless to brown) with the evolution of gaswas observed. The DMF was removed in vacuo and the resulting solidmass washed with THF (10 mL) and extracted with dichloromethane(12 mL). The extracts were filtered through Celite and reduced involume. Storage at �20 8C induced a precipitation of a bluish white solid,which was collected and recrystallised from dichloromethane by vapourdiffusion with diethyl ether to yield 4. Yield: 29%. 1H NMR (400 MHz,DMSO) d=7.70 (d, 1H �CH), 7.56 (d, 1H, �CH), 7.43 (s, 1 H, �CH),6.87 (d, 1H, �CH), 6.52 (d, 1H, �CH), 3.68 (s, 3H, �CH3), 3.46 (s, 3H, �CH3), 3.33 ppm (s, 3H, �CH3); 13C NMR (500 MHz, CDCl3): d=166.6,163.3, 138.2, 126.6, 122.9, 120.4, 117.5, 117.3, 111.3, 34.2, 34.1, 33.5 ppm;FT-IR (KBr): v=2445 (nB-H), 764 cm�1 (nC-S); ESI-MS [M]+ : accuratemass predicted 351.0686, found 351.0686; elemental analysis calcd (%)for C12H15N6BS3: C 41.14, H 4.32, N 23.99; found: C 41.22, H 3.90, N23.46.
Treatment of NaTmMe with iodine : NaTmMe (0.5 g, 1.34 mmol) was dis-solved in THF (20 mL) to which iodine (1.02 g, 4.02 mmol) was added.The reaction vessel was kept in the dark and stirred for six days. The sol-vent was removed and the residue was washed with diethyl ether toremove excess iodine. The sample was heated under vacuum (~60 8C) tosublime traces of iodine. The residue was recrystallised from dichlorome-thane by vapour diffusion with diethyl ether. Yield: 55%. The spectro-scopic data (mass spectrometry, 1H NMR and 13C NMR) were consistentwith the product from the reaction with NOBF4 described above.
Treatment of NaTmPh with iodine to form 5 : NaTmPh (0.13 g, 0.24 mmol)was dissolved in THF (40 mL) to which iodine (0.030 g, 0.12 mmol) wasadded. The reaction vessel was kept in the dark and stirred for six days.The solvent was removed and the residue was washed with diethyl ether
Table 2. X-ray crystallographic data.
2b 2c·MeOH 2d 2 f 4 6
formula C15H22B1I1N6S3 C17H28B1Br1N6O1S3 C17H26B1I1N6S3 C20H32B1I1N6S3 C12H15B1N6S3 C27H22B1I5N6S2
Mr 520.28 519.35 548.33 590.41 350.29 1139.94crystal system monoclinic monoclinic monoclinic monoclinic monoclinic tetragonalspace group C2/c P21/n P21/c C2/c P21/n I4a [��]1 11.6727(6) 13.7955(9) 14.1166(10) 35.667(3) 11.7625(2) 26.7733(6)b [��1] 17.3681(8) 11.1555(7) 13.8444(9) 13.8826(18) 14.0757(3) 26.7733(6)c [��1] 20.3656(11) 15.4311(12) 11.5688(6) 11.2541(10) 19.5814(5) 10.1745(3)a [8] 90 90 90 90 90 90b [o] 101.214(5) 100.007(7) 91.106(5) 95.421(9) 105.201(2) 90g [8] 90 90 90 90 90 90Z 8 4 4 8 8 8V [��3] 4049.9(4) 2338.7(3) 2260.5(2) 5547.6(10) 3128.57(12) 7293.2(3)mcalcd [mm�1] 1.904 2.047 1.710 1.399 0.478 4.405rflns measd 16696 15244 24298 8027 4660 10343unique reflns (Rint) 5068ACHTUNGTRENNUNG(0.0716) 5875 ACHTUNGTRENNUNG(0.0458) 5878ACHTUNGTRENNUNG(0.1233) 4395 ACHTUNGTRENNUNG(0.0907) 4493 ACHTUNGTRENNUNG(0.0423) 7408 ACHTUNGTRENNUNG(0.0172)observed reflns 3755 3283 2724 2980 3298 6773parameters 239 271 256 283 409 375R (I>2s(I))[a] 0.0531 0.0499 0.0681 0.145 0.0544 0.0434Rw (all reflns)[b] 0.1307 0.1146 0.1006 0.4025 0.1424 0.1070GOF 0.985 0.963 0.912 1.56 1.033 1.038
[a] R= [S j jFo j� jFc j j]/ ACHTUNGTRENNUNG[SjFoj]; [b] wR= [[SwACHTUNGTRENNUNG(Fo2�Fc
2)]/ ACHTUNGTRENNUNG[SwFo2]]1/2.
www.chemeurj.org � 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Chem. Eur. J. 0000, 00, 0 – 0
�� These are not the final page numbers!&6&
J. Reglinski, M. D. Spicer et al.
to remove excess iodine. The residue was recrystallised from dichlorome-thane by vapour diffusion with diethyl ether. Yield: 36%. 1H NMR(500 MHz, DMSO) d=8.30 (d, 2H, �CH), 8.11 (d, 2H, �CH), 8.00–7.4(arom 15H), 7.47 (d, 1H, �CH), 7.31 ppm (d, 1H, �CH); 13C NMR(500 MHz, CDCl3): d=137.88, 135.45, 133.21, 131.32, 130.60, 129.92,128.66, 127.62, 126.16, 126.10, 125.87, 125.49, 122.55, 120.88, 119.42 ppm;The 1H,13C,13C-135DEPT and the 1H,13C correlated NMR spectra aregiven in the Supporting Information for Htc2+ . ESI-MS [M]+ : accuratemass predicted 505.1350; found m/z 505.1435; elemental analysis calcd(%) for C27H22N6BS2I3·H2O: C 35.85, H 2.68, N 9.30; found: C 36.11, H3.27, N 8.78.
Treatment of NaTmPh with NO+ to form 5 : Reactions with nitrosoniumtetrafluoroborate led to the formation of oily substances that did not givegood spectroscopic data apart from mass spectrometry, which confirmedthe presence of 5.
Treatment of NaTmPh with phosphorus triiodide (PI3) to form 6 : NaTmPh
(0.14 g, 0.25 mmol) was stirred with 1 equiv phosphorous triiodide(0.1029 g, 0.25 mmol) in dry DCM (20 mL) under a nitrogen atmosphere.The dark red coloured solution was filtered and reduced the volume into2 mL. Vapour diffusion of this solution with diethyl ether gave dark redX-ray quality crystals. Yield 57 %. 1H NMR (400 MHz, DMSO): d=8.34(d, 2 H, �CH), 8.11 (d, 2H, �CH), 7.74 (br, 1H, �CH), 7.69–7.63 (broadmultiplets, 11H), 7.60–7.39 ppm (broad multiplets, 10 H) [see the Sup-porting Information]; 13C NMR (100 MHz, DMSO, 2 s relaxation delay):d=135.5, 133.1, 131.4, 130.6, 129.1, 129.0, 128.5, 126.4, 126.2, 126.0, 125.9,125.5, 124.7, 64.88 ppm; FT-IR (KBr): v =2470 (B-H), 765 (C=S),740 cm�1 (C-S); ESI-MS [TmPh�S]+: accurate mass predicted 505.1350,found 505.1432; elemental analysis calcd (%) for C27H22N6BS2I5: C 28.43,H 1.95, N 7.37; found: C 29.69, H 1.28, N 6.65. A second analysis was car-ried out after aggressive drying for C27H22N6BS2I3·H2O: C 35.85, H 2.68,N 9.30; found: C 35.36, H 3.66, N 8.97.
Note: Obtaining a satisfactory elemental analysis of this compound wasproblematic. There was concern that aggressive drying could lead to theloss of iodine. The analyses reported are our best fit. However, it still re-quired the addition of a water molecule of crystallisation (present in1H NMR spectra) to obtain agreement.
Density functional theory (DFT) molecular orbital calculations : Calcula-tions were performed using the Gaussian 03 program.[28] The molecularspecies were subjected to geometry optimisation at the DFT levelB3LYP using a 6-311G** basis set.[29–35] The optimized species were sub-jected to a frequency analysis. The energy values quoted herein includethe zero-point energy values. The charges reported are the Mulliken pop-ulation charges.
X-ray data : CCDC-918578 (2 b), -918579 (2 c), -918580 (2d), -918581(2 f), -918582 (4) and -918583 (6) contain the supplementary crystallo-graphic data for this paper. These data can be obtained free of chargefrom The Cambridge Crystallographic Data Centre via www.ccdc.cam.a-c.uk/data_request/cif.
Acknowledgements
R.R.N. gratefully acknowledges financial support from Strathclyde Uni-versity. S.L.T. gratefully acknowledges financial support from the Com-monwealth Scholarship Commission.
[1] M. D. Spicer, J. Reglinski, Eur. J. Inorg. Chem. 2009, 1553 –1574.[2] A. A. Mohamed, D. Rabinovich, J. P. Fackler, Acta Crystallogr. Sect.
E 2002, 58, m726 – 727.[3] D. V. Patel, D. J. Mihalcik, K. A. Kreisel, G. A. P. Yap, L. N. Zakhar-
ov, W. S. Kassel, A. L. Rheingold, D. Rabinovich, Dalton Trans.2005, 2410 – 2416.
[4] C. A. Dodds, M. Garner, J. Reglinski, M. D. Spicer, Inorg. Chem.2006, 45, 2733 –2741.
[5] P. J. Bailey, D. J. Lorono-Gonzales, C. McCormack, S. Parsons, M.Price, Inorg. Chim. Acta 2003, 354, 61 –67.
[6] L. A. Graham, A. R. Fout, K. R. Kuehne, J. L. White, B. Mookherji,F. M. Marks, G. P. A. Yap, L. N. Zakharov, A. L. Rheingold, D. Ra-binovich, Dalton Trans. 2005, 171 – 180.
[7] P. J. Bailey, L. Budd, F. A. Cavaco, S. Parsons, F. Rudolphi, A. San-chez-Perucha, F. J. White, Chem. Eur. J. 2010, 16, 2819 –2829.
[8] R. Rajasekharan-Nair, D. Moore, K. Chalmers, D. Wallace, L. M.Diamond, L. Darby, J. Reglinski, M. D. Spicer, Chem. Eur. J. 2013,19, 2487 –2495.
[9] I. R. Crossley, A. F. Hill, E. R. Humphery, M. K. Smith, N. Tsha-bang, A. C. Willis, Chem. Commun. 2004, 1878 – 1879.
[10] M. Schwalbe, P. C. Andrikopoulos, D. R. Armstrong, J. Reglinski,M. D. Spicer, Eur. J. Inorg. Chem. 2007, 1351 –1360.
[11] F. Freeman, J. W. Ziller, H. N. Po, M. C. Keindl, J. Am. Chem. Soc.1988, 110, 2586 –2591.
[12] F. Bigoli, P. Deplano, M. L. Mercuri, M. A. Pellinghelli, A. Sabatini,E. F. Trogu, A. Vacca, J. Chem. Soc. Dalton Trans. 1996, 3583 – 3589.
[13] G. J. Corban, S. K. Hadjikakou, N. Hadjiliadis, M. Kubicki, E. R. T.Tiekink, I. S. Butler, E. Drougas, A. M. Kosmas, Inorg. Chem. 2005,44, 8617 –8627.
[14] F. Isaia, M. C. Aragoni, M. Arca, F. Demartin, F. A. Devillanova, G.Floris, A. Garau, M. B. Hursthouse, V. Lippolis, R. Medda, F. Oppo,M. Pira, G. Verani, J. Med. Chem. 2008, 51, 4050 – 4053.
[15] S. Amado, A. P. Dicks, D. L. H. Williams, J. Chem. Soc. PerkinTrans. 2 1998, 1869 – 1876.
[16] F. Saczewski, M. Gdaniec, J. Chem. Soc. Perkin Trans. 1 1992, 47 –50.
[17] C. Kimblin, B. M. Bridgewater, D. G. Churchill, G. Parkin, Chem.Commun. 1999, 2301 – 2302.
[18] B. M. Bridgewater, G. Parkin, J. Am. Chem. Soc. 2000, 122, 7140 –7141.
[19] S. Senda, Y. Ohki, T. Hirayama, D. Toda, J. L. Chen, T. Matsumoto,H. Kawaguchi, K. Tatsumi, Inorg. Chem. 2006, 45, 9914 – 9925.
[20] J. Fernandez-Bolanos, J. F.-B. Guzman, J. F. Mota, Carbohydr. Res.1985, 145, 152 –155.
[21] S. Sauerbrey, P. K. Majhi, G. Schnakenburg, A. J. Arduengo III, R.Streubel, Dalton Trans. 2012, 41, 5368 – 5376.
[22] V. O. Iaroshenko, S. Mkrtchyan, A. Gevorgyan, M. Miliutina, A. Vil-linger, D. Volochnyuk, V. Y. Sosnovskikh, P. Langer, Org. Biomol.Chem. 2012, 10, 890 – 894.
[23] J. Reglinski, M. Garner, I. D. Cassidy, P. A. Slavin, M. D. Spicer,D. R. Armstrong, J. Chem. Soc. Dalton Trans. 1999, 2119 –2126.
[24] S. Bakbak, V. K. Bhatia, C. D. Incarvito, A. L. Rheingold, D. Rabi-novich, Polyhedron 2001, 20, 3343 –3348.
[25] G. M. Sheldrick, SHELXS-97 Program for crystal structure refine-ment, University of Gçttingen, Germany 1997.
[26] A. Altomare, G. Cascarano, C. Giacovazzo, A. Guagliardi, J. Appl.Crystallogr. 1993, 26, 343 – 350.
[27] L. J. Farrugia, J. Appl. Crystallogr. 1999, 32, 837 – 838.[28] Gaussian, Revision03, M. J. Frisch, G. W. Trucks, H. B. Schlegel,
G. E. Scuseria, M. A. Robb, J. A. M. Cheeseman, T. Vreven, K. N.Kudin, J. C. Burant, J. M. Millam, S. S. Lyengar, J. Tomasi, V.Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G. A. Peters-son, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Ha-segawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, M.Klene, X. Li, J. E. Knox, H. P. Hratchian, J. B. Cross, C. Adamo, J.Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R.Cammi, C. Pomelli, J. W. Ochterski, P. Y. Ayala, K. Morokuma,G. A. Voth, P. Salvador, J. J. Dannenberg, V. G. Zakrzewski, S. Dap-prich, A. D. Daniels, M. C. Strain, O. Farkas, D. K. Malick, A. D.Rabuck, K. Raghavachari, J. B. Foresman, J. V. Ortiz, Q. Cui, A. G.Baboul, S. Clifford, J. Cioslowski, B. B. Stefanov, G. Liu, A. Liashen-ko, P. Piskorz, I. Komaromi, R. L. Martin, D. J. Fox, T. Keith, M. A.Al-Laham, C. Y. Peng, A. Nanayakkara, M. Challacombe, P. M. WGill, B. Johnson, W. Chen, M. W. Wong, C. Gonzalez, J. A. Pople,Gaussian, Inc., Wallingford, 2004.
[29] P. Hohenbeg, W. Kohn, Phys. Rev. 1964, 136, 8864 –8871.[30] W. Kohn, L. J. Sham, Phys. Rev. 1965, 140, A1133 – A1138.
Chem. Eur. J. 2013, 00, 0 – 0 � 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.chemeurj.org
These are not the final page numbers! ��&7&
FULL PAPERSoft Scorpionate Anions
[31] C. Lee, W. Yang, Phys. Rev. B 1988, 37, 785 –789.[32] B. Miehlich, A. Savin, H. Stoll, H. Preuss, Chem. Phys. Lett. 1989,
157, 200 –206.[33] A. D. McLean, G. S. Chandler, J. Chem. Phys. 1980, 72, 5639 – 5648.[34] R. Krishnan, J. S. Binkley, R. Seeger, J. A. Pople, J. Chem. Phys.
1980, 72, 650 –654.
[35] M. N. Glukhovtsev, A. Pross, M. P. McGrath, L. Radom, J. Chem.Phys. 1995, 103, 1878 –1885.
Received: January 10, 2013Revised: June 18, 2013
Published online: && &&, 0000
www.chemeurj.org � 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Chem. Eur. J. 0000, 00, 0 – 0
�� These are not the final page numbers!&8&
J. Reglinski, M. D. Spicer et al.
Scorpionates
R. Rajasekharan-Nair, A. Marckwordt,S. T. Lutta, M. Schwalbe, A. Biernat,D. R. Armstrong, A. J. B. Watson,A. R. Kennedy, J. Reglinski,*M. D. Spicer* . . . . . . . . . . . . . . . . . &&&&—&&&&
Soft Scorpionate Anions as Platformsfor Novel Heterocycles
Tail strike : Soft scorpionates have thusfar been seen mainly as a family ofligands. Their chemistry is extended
here to the production of novel cati-ons, macrocycles and unusual polycy-clic heterocycles (see scheme).
Chem. Eur. J. 2013, 00, 0 – 0 � 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.chemeurj.org
These are not the final page numbers! ��&9&
FULL PAPERSoft Scorpionate Anions