Synthesis and Characterization of the 17-Valence Electron Tris(2-pyridyl)Phosphine Oxide Ligated Chromium Nitrosyl Complex.

Date2009/01/20

OutlineIntroduction - Discovery of 17-e- compounds - Classification of 17-e- compounds - NO releasing complexes

Experimental - [OP(2-py)3M(CO)3-n(NO)n](BF4)n M = Cr, Mo, W ; n = 0~2 - [OP(2-py)3Cr(MeCN)2(NO)](BF4)2 - Characterization of 16-e-, 17-e- and 18-e- complexes

Conclusions - Plausible Formation Pathways for 17-e- [OP(2-py)3Cr(MeCN)2(NO)](BF4)2

Paramagnetic Organochromium Complexeswith 17 Valence ElectronsStrametz, H.; Fischer, E. 0. J. Organomet. Chem. 1967, 10, 32318 e-17 e-

17-Valence Electron Organochromium Complexes(1) Hexacoordinated Species[CrL6]+Michael C. Baird, Chem. Rev. 1988. 88. 1217-1227dppm = Ph2PCH2PPh2, LEt = carbenoid ligand, dmpe = Me2P(CH2)2PMe2

complexesCO, cm-1gav[Cr(CO)6]+1.982[trans-Cr(CO)4(PPh3)2]+19902.027[cis-Cr(CO)4(dppm)] +2084, 2033, 19692.009[mer-Cr(CO)3(P(OMe)3)3]+2051, 1988, 19352.002[mer-Cr(CO)3(PMe2Ph)3]+2010, 1940, 19042.019[Cr(CO)3(dmpe)(LEt)] +2010, 1930, 18902.019

17-Valence Electron Organochromium Complexes(2) Cyclopentadienyl SpeciesCpCrL3dppb = Ph2P(CH2)4PPh2, dpph = Ph2P(CH2)6PPh2Michael C. Baird, Chem. Rev. 1988. 88. 1217-1227

complexesCO, cm-1(5-C5H5)Cr(CO)2(PEt3)1924, 1805(5-C5H5)Cr(CO)2(PBu3)1921, 1803(5-C5H5)Cr(CO)2(PCy3)1919, 1802(5-C5H5)Cr(CO)2(PPh3)1920, 1800(5-C5H5)Cr(CO)2(PMe2Ph)1925, 1807(5-C5H5)Cr(CO)2(PEt2Ph)1923, 1807[(5-C5H5)Cr(CO)2]2(-dppb)1915, 1806[(5-C5H5)Cr(CO)2]2(-dpph)1915, 1795

17-Valence Electron Organochromium Complexes(3) Nitrosyl Species[Cr(NO)L5-nXn](2-n)+ n = 0~1Wigley, D. E.; Walton, R. A. Organometallics 1982, 1, 1322-1327

Paramagnetic Organochromium Complexeswith 17 Valence ElectronsPeter Legzdins, J. Am. Chem. SOC. 1991, 113, 7049-705017 e-Linear NO Cr-N-O = 174.3 IR (KBr) NO 1611 cm-1IR (hexanes) NO 1631 cm-1

Ligand with Only - Donating Character Stabilizes 17 Electron StructurePeter Legzdins, J. Am. Chem. SOC. 1994, 116, 6021-6022-donor ligands such as NH3 & MeCN stabilize the 17 e- cationic compounds.-acceptor ligands such as CO stabilize the 18 e- configuration in the neutral complexe.Linear NO 170.3 (3)IR (Nujol) NO 1667 cm-1IR (THF) NO 1676 cm-1IR (Nujol) NO 1709 cm-1IR (MeCN) NO 1710 cm-1IR (Nujol) CN 2326 cm-1IR (Nujol) CN 2297 cm-1

Photo-Induced Nitric Oxide Releasing Prakash, R. J. Am. Chem. Soc. 2005, 127, 13758-13759Ford, P. C. J. Am. Chem. Soc. 2006, 128, 3831-3837

Photo-Induced Nitric Oxide Releaing (continued)Mascharak, P. K. J. Am. Chem. Soc. 2006, 128, 7166-7167.

Paramagnetic Organochromium Complexes 2006 C3v16 e- , Triplet S = 117 e- , Doublet S = 1/218 e- , Singlet S = 0M = Cr , Mo , W18 e- , Singlet S = 0M = Mo , W

Synthesis of [OP(2-py)3M(CO)3]M = Cr Mo W 2006 C3v

Crystal structure of [OP(2-py)3M(CO)3]M = CrM = MoS. Joyce Yu, J. Organomet. Chem. 1999, 588, 260267

UV and IR of [OP(2-py)3M(CO)3]M = CrMoW 2006 C3vPurple

Synthesis of [OP(2-py)3M(CO)2(NO)](BF4)M = Cr Mo W 2006 C3v

Crystal structure of [OP(2-py)3M(CO)2(NO)](BF4)M = CrM = Mo 2006 C3v

SQUID Data of [OP(2-py)3Cr(CO)2(NO)](BF4)eff = g(S(S+1))1/2 ;

S=1g = 1.9790

eff =2.80 ()

eff = (3k/N2)1/2(mT)1/2

= 2.828(mT)1/2

eff :2.87=> Triplet S = 1 2006 C3v

Robert H. Crabtree, The organometallic chemistry of the transition metals, Wiley eff :2.80

eff :2.87

UV and IR of [OP(2-py)3M(CO)2(NO)](BF4) M = Cr Mo W 2006 C3vYellow

Synthesis of [OP(2-py)3M(CO)(NO)2](BF4)2M = Cr Mo W 2006 C3v

Crystal structure of [OP(2-py)3M(CO)(NO)2](BF4)2M = MoM = Cr 2006 C3v

SQUID Data of [OP(2-py)3Cr(CO)(NO)2](BF4)2eff = g(S(S+1))1/2 ;

S=1g = 1.9560

eff =2.77 ()

eff = (3k/N2)1/2(mT)1/2

= 2.828(mT)1/2

eff :2.86=> Triplet S = 1 2006 C3v

Robert H. Crabtree, The organometallic chemistry of the transition metals, Wiley eff :2.77

eff :2.86

UV and IR of [OP(2-py)3M(CO)(NO)2](BF4)2 M = Cr Mo W 2006 C3vGreen

Synthesis of [OP(2-py)3Cr(MeCN)2(NO)](BF4)2M = Cr17 e- , Doublet S = 1/2M = Mo , W18 e- , Singlet S = 0M = Cr , Mo , WYield = 75 %

IR of [OP(2-py)3Cr(MeCN)2(NO)](BF4)21eq NO CN CN NO Cr 2323 2295 1753 CO CO NO Cr 2047 1970 1718Mo 2036 1953 1685W 2017 1933 1670 2eq NO CN CN NO Cr 2323 2295 1753 CO NO NO Cr 2029 1889 1742Mo 2037 1826 1716W 2148 1774 1687

IR of [OP(2-py)3Cr(MeCN)2(NO)](BF4)2

UV of [OP(2-py)3Cr(MeCN)2(NO)](BF4)2

Near-IR of 17-e- [OP(2-py)3Cr(MeCN)2(NO)](BF4)2

Crystal structure of 17-e-[OP(2-py)3Cr(MeCN)2(NO)](BF4)2Bond length ()Cr1-N51.696(3)Cr1-N42.044(3)Cr1-N62.045(3)Bond angle (o)C18-N6-Cr1169.2(3) C16-N4-Cr1176.2(3)O2-N5-Cr1179.1(3)

Theoretical Studies of the UV Spectrum of[OP(2-py)3Cr(MeCN)2(NO)](BF4)2

Theoretical studies of [OP(2-py)3Cr(MeCN)2(NO)](BF4)2

EPR of [OP(2-py)3Cr(MeCN)2(NO)](BF4)2gav = 1.9896Wigley, D. E.; Walton, R. A. Organometallics 1982, 1, 1322-1327.Solid77 K

SQUID Data of [OP(2-py)3Cr(MeCN)2(NO)](BF4)2 eff = g(S(S+1))1/2 ;

S=0.5g = 1.9896

eff =1.72 ()

eff = (3k/N2)1/2(mT)1/2

= 2.828(mT)1/2 eff :1.90=> Doublet S = 1/2

Robert H. Crabtree, The organometallic chemistry of the transition metals, Wiley eff :1.72

eff :1.90

EPR and SQUID data of Cr complexes[OP(2-py)3Cr(MeCN)2(NO)](BF4)2 1.9896 1.72 / 2.09 2006 C3vComplexes

XPS Data of Cr Complexes

Possible Mechanism for the Formation of Triplet [OP(2-Py)3Cr(CO)2(NO)](BF4)

Possible Mechanism for the Formation of Triplet [OP(2-Py)3Cr(CO)(NO)2](BF4)2

Study of the Formation Mechanism for 17-e- [OP(2-py)3Cr(MeCN)2(NO)](BF4)2 (I)

Study of the Formation Mechanism for 17-e- [OP(2-py)3Cr(MeCN)2(NO)](BF4)2 (II)

Study of the Formation Mechanism for 17-e- [OP(2-py)3Cr(MeCN)2(NO)](BF4)2 (III)

Plausible Formation Pathways for 17-e- complex

NO-Trapping ExperimentGSNOmax = 546 nmGrossiand L., DAngelo S. J. Med. Chem. 2005, 48, 2622-2626.

NO-Trapping Experiment546 nm735 nm546 nm735 nm[OP(2-py)3Cr(CO)(NO)2](BF4)2 + GSHIn MeCN[OP(2-py)3Cr(CO)(NO)2](BF4)2 + GSHIn MeCN and H2O

ConclusionsWe have synthesized a rare 17-electronic chromium complexe [OP(2-py)3Cr(MeCN)2(NO)](BF4)2 in high yield.

Mechanism of the formation of 17-electron complex was proposed by using UV and IR spectrometrey spectrometer.

A solvent-induced release of NO radical was demonstrated for these Cr complexes.

These paramagnetic chromium complexes might be potentially useful nitric oxide (NO) delivery agents.