0022-4766/13/5406-1083 © 2013 by Pleiades Publishing, Ltd. 1083

Journal of Structural Chemistry. Vol. 54, No. 6, pp. 1083-1090, 2013

Original Russian Text © 2013 G. I. Zharkova, I. A. Baidina, A. I. Smolentsev, I. K. Igumenov

PROPERTIES AND STRUCTURE OF NEW VOLATILE

PHENYL-CONTAINING β-DIKETONATES

OF TRIMETHYLPLATINUM(IV):

(CH3)3Pt(btfa)H2O, (CH3)3Pt(bac)Py,

AND INITIAL COMPLEX [(CH3)3PtI]4

G. I. Zharkova, I. A. Baidina, A. I. Smolentsev,

and I. K. Igumenov

UDC 546.92:547.442:548.737

By interaction of trimethylplatinum(IV) iodide with phenyl-containing β-diketonates, the volatile

monomeric complexes of trimethylplatinum(IV) based on benzoyltrifluoroacetone (Hbtfa) and

benzoylacetone (Hbac) of the composition (CH3)3Pt(btfa)H2O (I) and (CH3)3Pt(bac)Py (II) are obtained.

Synthesis of the complexes is described; data of elemental analysis and IR spectra are reported; thermal

characteristics are studied by thermogravimetry. For the first time, a single crystal X-ray diffraction study

of complexes (I), (II), and the initial tetrameric complex [(CH3)3PtI]4 (III) is performed.

DOI: 10.1134/S0022476613060127

Keywords: β-diketonates of trimethylplatinum(IV), synthesis, structure, volatility, thermal properties.

To the known volatile Pt(IV) compounds used in MO CVD for obtaining platinum coatings, the volatile complexes

of platinum(IV) with β-diketonates [1-3] can be primarily attributed. The important properties of these compounds, such as

volatility (a noticeable vapor pressure at comparatively low temperatures) and relatively high thermal stability in the

condensed and gaseous states, make it possible to use them in CVD for obtaining metal films of platinum of different

functionality (corrosion-, erosion-, thermal-, wear-resistant, dielectric, superconductive, semiconductive, catalytic, etc.).

The analysis of the literature data shows that almost all volatile β-diketonates of platinum(IV) are produced based on

the derivatives of trimethylplatinum(IV). The most frequently used initial compound is a metal-organic complex [(CH3)3PtI]4.

For the first time, trimethylplatinum iodide was obtained in 1909 [4] in the interaction of the Grignard reagent with

platinum(IV) tetrachloride with a yield of less than 20%. The authors isolated crystalline orange substance–trimethylplatinum

iodide (CH3)3PtI. In more recent works, this complex was obtained from non-aqueous salt K2PtCl6 and CH3MgI with the

yields of 55% [5] and 80% [6]. In this compound, iodine is easily substituted by different anions, for example, Cl–, OH–, Br–,

3NO .

− The common properties of these compounds are a high bond strength between platinum and methyl groups, the

stabilization of the oxidation state 4+, and the retention of platinum coordination number of 6. A single crystal X-ray

diffraction study of trimethylplatinum chloride [7] and trimethylplatinum hydroxide [8] confirms their tetrameric structure.

In these compounds, platinum has an octahedral environment; the chlorine atoms or hydroxyl groups are bridging ones. There

A. V. Nikolaev Institute of Inorganic Chemistry, Siberian Division, Russian Academy of Sciences, Novosibirsk; zharkova@niic.nsc.ru. Translated from Zhurnal Strukturnoi Khimii, Vol. 54, No. 6, pp. 1052-1059, November-December, 2013. Original article submitted October 10, 2012.

1084

are no data on the structural study of pure iodide complex [(CH3)3PtI]4 in the literature; only the works on the structural study

of solvate complexes of trimethylplatinum iodide are available [9-11].

Trimethylplatinum(IV) with β-diketones forms dimeric complexes with a common formula [Me3Pt(R–CO–CH–CO–

R1)]2, where R and R1 are simple alkyl radicals from CH3 to C5H11 [12, 13]. A complex of trimethylplatinum with

benzoylacetone [Me3Pt(bac)]2, which we have for the first time obtained and studied in [14], also has a dimeric structure. In

dimeric chelates of trimethylplatinum, β-diketone acts as a tridentate ligand, where along with two donor oxygen atoms there

is the third donor: the middle atom of the carbon ring; the bridging Pt–Cγ bond forms, and through this a dimer forms. Due to

their low volatility such compounds are less suitable for practical use in CVD than the β-diketonates of trimethylplatinum

with a monomeric structure. The introduction of CF3 groups into the chelate ligand [15] contributes to the volatility of the

complexes. Prior to our studies, fluorinated β-diketonates of trimethylplatinum(IV) had not been known in the literature.

Previously, we have found [14] that fluorinated β-diketones do not form dimeric complexes, and the formation of monomeric

fluorinated β-diketonate of trimethylplatinum is conditioned by the presence of a donor molecule (for example H2O) in the

reaction medium, which should occupy the sixth coordination site of platinum in the monomeric β-diketonate complex. For

this reason, we initially failed to produce fluorinated β-diketonates of trimethylplatinum in non-aqueous solvents. Water in

the composition of fluorinated adducts can be easily replaced with a stronger base, for example, pyridine. Moreover,

treatment of dimeric β-diketonates of trimethylplatinum with pyridine also breaks the bridging Pt–Cγ bond with the formation

of monomeric β-diketonate adducts of trimethylplatinum, which can be the most promising precursors in CVD due to their

enhanced thermal properties [16].

Here, we have obtained and studied the structures of monomeric phenyl-containing β-diketonates of

trimethylplatinum(IV): [(CH3)3Pt(C6H5–CO–CH–CO–CF3)H2O] (I) and [(CH3)3Pt(C6H5–CO–CH–CO–CH3)Py] (II) produced

based on benzoyltrifluoroacetone (Hbtfa) and benzoylacetone (Hbac); the methods used to synthesize the complexes are

described; the data of elemental analysis, IR spectra, TG analysis are reported. For the first time, the single crystal X-ray

diffraction study of complexes (I), (II), and initial complex [(CH3)3PtI]4 (III) was performed. The Cambridge Structure Data

Base (CSDB) does not contain the structural data on compounds (I-III).

EXPERIMENTAL

As the precursor for the synthesis of β-diketonates of trimethylplatinum(IV), trimethylplatinum(IV) iodide

[(CH3)3PtI]4 was used. The complex was synthesized based on the technique described in [5]. We have optimized the

conditions of this synthesis, which allowed us to increase the yield of [(CH3)2PtI]4 from 55% to 75% [17].

Synthesis of (CH3)3Pt(C6H5–CO–CH–CO–CF3)H2O (I). The (CH3)3PtI complex (1 g, 2.8 mmol) was dissolved in

50 ml of benzene. To the obtained orange solution, 1.42 g (5.6 mmol) of potassium salt of benzoyltrifluoroacetone (Kbtfa) in

10 ml of 96% ethanol were added and powdered with AgF salt (0.35 g, 2.8 mmol). The reaction mixture was stirred on a

magnetic stirrer at 45-50°C until decolorization of the solution and precipitation of AgI and KF salts. The residue was filtered

off, the solution was completely evaporated. The dry residue was extracted with hexane. The product isolated from hexane

was purified by sublimation at reduced pressure. The yield of the sublimated complex was 1.23 g (93%). Light yellow

crystals, Tm = 148-150°C. Found, %: C 32.9, H 3.8, F 11.9. For C13H17F3O3Pt calculated, %: C 33.0, H 3.6, F 12.0.

IR spectrum (I) (ν, cm–1): 3627, 3308, 3189.2963, 2899, 2813, 1608, 1542, 1530, 1490, 1457, 1429, 1285, 1257,

1196, 1183, 1131, 1053, 1023, 937, 807, 769 722, 701, 654, 584, 533, 408.

Synthesis of (CH3)3Pt(C6H5–CO–CH–CO–CH3)Py (II). The (CH3)3PtI complex (1 g, 2.8 mmol) was dissolved in

50 ml of chloroform; to the orange solution, the solution of 1.18 g (5.6 mmol) of potassium salt of benzoylacetone (Kbac) in

20 ml of ethanol was added. The reaction mixture was stirred at 40-50°C until decolorization of the solution. Then, 5.6 mmol

of pyridine (Py) were added into the solution, and the reaction mixture was boiled for 1 h. After that, the solvent and excess

pyridine were evaporated in a water bath at reduced pressure. The dry residue was extracted with hexane. The product

1085

TABLE 1. Crystallographic Data and the Parameters of Single Crystal X-Ray Diffraction Experiments for Complexes I, II, III

Parameter (CH3)3Pt(btfa)H2O I (CH3)3Pt(bac)Py II [(CH3)3PtI]4 III

Chemical formula C13H17F3O3Pt C18H23NO2Pt C12H36I4Pt4

M 473.36 480.46 1468.37

T, K 240(2) 296(2) 150(2)

Crystal symmetry Triclinic Monoclinic Monoclinic

Space group P–1 P21/c C2/m

a, Å 6.1653(5) 6.802(2) 14.1157(4)

b, Å 9.9412(7) 16.077(6) 14.3600(4)

c, Å 12.3913(10) 16.288(6) 13.0516(3)

α, deg 101.075(4)

β, deg 91.353(5) 94.822(10) 95.2770(10)

γ, deg 99.535(4)

V, Å3 733.82(10) 1774.9(11) 2634.37(12)

Z 4 4 4

ρ(calc), g/cm3 2.142 1.798 3.702

μMo, mm–1

F(000)

Crystal size, mm

9.597

448

–

7.912

928

0.28×0.12×0.07

25.855

2528

0.18×0.18×0.08

θ range, deg 1.68–28.30 2.51–30.53 2.48–27.53

Intervals of h, k, l –8 ≤ h ≤ 8,

–13 ≤ k ≤10,

–16 ≤ l ≤ 16

–8 ≤ h ≤ 8,

–22 ≤ k ≤ 22,

–23 ≤ l ≤ 23

–18 ≤ h ≤ 18,

–18 ≤ k ≤ 18,

–12 ≤ l ≤ 16

Number of measured Ihkl

Number of independent Ihkl

Data collection over θ = 25.0°, %

Max and min transmission

7535

3469 (R(int) = 0.0367)

95.9

0.9101 and 0.4470

15434

5034 (R(int) = 0.0526)

94.2

0.6074 and 0.2154

5169

3140 (R(int) = 0.0168)

99.9

0.2315 and 0.0898

GOOF for 2

hklF 1.100 1.041 1.027

R factor [I > 2σ(I)]

R factor (all reflections)

R1 = 0.0732,

wR2 = 0.2139

R1 = 0.0822,

wR2 = 0.2184

R1 = 0.0479,

wR2 = 0.1019

R1 = 0.0982,

wR2 = 0.1172

R1 = 0.0197,

wR2 = 0.0414

R1 = 0.0237,

wR2 = 0.0424

Residual electron density (max/min), e/Å3

6.940/–3.025 3.120/–1.895 1.117/–1.048

isolated from hexane was purified by sublimation at reduced pressure. The yield of the sublimated complex was 1.21 g

(90%). Light yellow crystals, Tm = 128-129°C. Found, %: C 45.2, H 5.0, N 2.7. For C18H23NO2Pt calculated, %: C 45.0, H

4.8, N 2.9.

IR spectrum (II) (ν, cm–1): 3066, 2951, 2890, 2813, 1592, 1560, 1506, 1483 , 1446, 1391, 1274, 1207, 1109, 1067,

1014, 943, 849, 760, 714, 694, 608, 536, 452.

IR spectra of complexes I and II in the range 400-4000 cm–1 were recorded on a Scimitar FTS-2000 spectrometer

(pellets with КBr).

The thermal study of the complexes was performed by thermogravimetry on a NETZSCH TG 209 F1 under the

same conditions: the temperature range 20-350°C, heating rate 10 deg/min, gas flow 30 ml/min, portion weight 5-6 mg, a

standard open crucible.

1086

TABLE 2. Main Geometric Characteristics of the Studied Complexes (interatomic distances d, Å, and angles ω, deg)

Parameter (CH3)3Pt(btfa)H2O I (CH3)3Pt(bac)Py II

Pt–CH3 2.000-2.009 ⟨2.003⟩ 2.028-2.042 ⟨2.035⟩

Pt–OL 2.171 (Ph), 1.23(CF3) 2.152 (CH3), 2.132 (Ph)

Pt–Ow 2.247 —

Pt–N — 2.183

O–C 1.28 (Ph), 1.27 (CF3) ⟨1.264⟩

C–Cγ 1.42 (Ph), 1.37 (CF3) ⟨1.392⟩

C–CMe 1.47 (Ph), 1.53 (CF3) 1.528 (CH3), 1.493 (Ph)

C–F ⟨1.32⟩ —

C–C 1.30-1.40 ⟨1.37⟩ 1.368-1.393 ⟨1.376⟩

O–Pt–O ⟨87.3⟩ ⟨89.1⟩

TABLE 3. Main Interatomic Distances d, Å, and Angles ω, deg, for [(CH3)3PtI]4

Distance d Distance d Angle ω

Pt(1)–C(13) 2.086(6) Pt(1)–I(1) 2.7836(3) C–Pt–С 86.5(2)-89.1(2)

Pt(1)–C(12) 2.087(5) Pt(1)–I(3) 2.8241(4) C–Pt–I 91.7(2)-94.2(2)

Pt(1)–C(11) 2.094(5) Pt(1)–I(2) 2.8287(3) I–Pt–I 85.78(1)-87.26(1)

Pt(2)–C(22) 2.072(8) Pt(2)–I(1) 2.8121(5) Pt–I–Pt 92.52(1)-95.15(1)

Pt(2)–C(21) 2.097(5) Pt(2)–I(3) 2.8255(3)

Pt(3)–C(31) 2.057(5) Pt(3)–I(2) 2.8004(5)

Pt(3)–C(32) 2.107(7) Pt(3)–I(3) 2.8279(3)

Single crystal X-ray diffraction study. Unit cell parameters and experimental intensities for the solution of the

crystal structures of complexes I-III were measured on an automated four-circle Bruker-Nonius X8 Apex diffractometer

(two-dimensional CCD detector, MoKα radiation, λ = 0.71073 Å, graphite monochromator). The structures of the complexes

were solved by the direct method and refined in the anisotropic approximation. Hydrogen atoms were located geometrically

and included in the refinement in the isotropic approximation together with non-hydrogen atoms. Crystallographic

characteristics and parameters of the experiment are given in Table 1. Main geometric characteristics of the complexes

(interatomic distances and bond angles) are listed in Tables 2 and 3. All calculations were performed using the SHELX-97

software (Bruker AXS Inc., 2004) [18]. Diffraction patterns of the studied compounds were fully indexed by the results of the

single crystal study.

Atomic coordinates and parameters of the complexes were deposited with the Cambridge Structural Database under

No. 904019 for I, No. 903820 for II, No. 815841 for III; see deposit@ccde.cam.ac.uk.

RESULTS AND DISCUSSION

The synthesized monomeric β-diketonates of trimethylplatinum(IV) based on phenyl-containing β-diketones are the

crystalline substances; they are stable if stored under normal conditions, retain their composition in multiple sublimation

under vacuum, and are very soluble in common organic solvents.

IR spectra of compounds I and II confirm a chelate-type bonding between the platinum atom and β-diketone. The

(C–H) and (Pt–CH3) stretching vibrations are observed in the range 3000-2800 cm–1. Characteristic vibrations of C–O and

C=C of the chelate ring manifest themselves in the range 1610-1450 cm–1. Less intense bands in the range 500-600 cm–1

correspond to the vibration of Pt–C bonds [19]. The presence of water in complex I is confirmed by a strong absorption band

of the stretching vibrations of O–H groups in at 3627 cm–1 and a wide hydrogen-bond band in the doublet form (3308 cm–1

1087

Fig. 1. Thermogravimetric curves of the complexes: (CH3)3Pt(btfa)H2O (I), (CH3)3Pt(bac)Py (II), [(CH3)3Pt(bac)]2 (III).

and 3187 cm–1). In our opinion, a weak absorption band at 3067 cm–1 for complex II corresponds to the (=C–H) stretching

vibrations of pyridine, according to [20].

Thermal study of the complexes was performed by thermogravimetry. The TG curves of (CH3)3Pt(btfa)H2O and

(CH3)3Pt(bac)Py are given in Fig. 1. In order to compare the thermal properties of β-diketonates of trimethylplatinum with

monomeric and dimeric structures, the figure also depicts the TG curve of the dimeric complex of trimethylplatinum with

benzoylacetone [(CH3)3Pt(bac)]2 obtained under the same measurement conditions. The analysis of TG curves shows that the

studied monomeric β-diketonates of trimethylplatinum exhibit high volatility; the complexes begin to lose weight due to

sublimation at low temperatures (∼50-100°C), although, under the given measurement conditions, the sublimation processes

occurred on the background of their insignificant decomposition. As compared to the monomeric complexes, under our

conditions, the dimeric [(CH3)3Pt(bac)]2 complex (Fig. 1, curve III) did not sublimate on heating up to 200°C, and further

heating resulted in its melting with the one-step decomposition. The TG study shows that a reduced thermal stability of the

monomeric adducts of trimethylplatinum is offset by their high volatility, as opposed to benzoylacetonate of

trimethylplatinum(IV) with the dimeric structure, in which these properties are inversely related. By their thermal

characteristics, monomeric β-diketonates of trimethylplatinum based on phenyl-containing ligands can be successfully used

as precursors in CVD, as well as other β-diketonates of trimethylplatinum with the monomeric structure for the first time

obtained and studied by us earlier [16, 17].

Description of crystal structures. Light yellow colored compounds I and II crystallize in the form of prisms with

monoclinic symmetry. Single crystals of the [(CH3)3PtI]4 complex were grown from the compound solution in hexane at

room temperature. The crystals are flattened orange prisms.

The structure of I is of molecular type; it is formed from neutral (CH3)3Pt(btfa)H2O complexes; the structure of the

complex is shown in Fig. 2a. Octahedral coordination of platinum (PtC3O3) is formed of three carbon atoms of methyl

groups, two oxygen atoms of the fluorinated β-diketonate ligand, and oxygen atom of the water molecule. The deviations of

the bond cis-angles from the ideal 90° on the central Pt atoms do not exceed 5°. The average Pt–CH3 bond length is 2.003 Å.

The Pt–Om and Pt–Ow distances are 2.150 Å and 2.247 Å respectively; the O–Pt–O chelate bond angle in the metal ring is

87.3°. In the β-diketonate ligand, the O–C bonds are almost similar (1.27 Å); a difference between the C–Cγ and C–CMe bond

lengths from the side of different substituents is ∼0.05 Å; the dispersion of the C–C distances in the substituent is up to 0.1 Å;

the bend angles of the chelate metal rings along the O…O line are in a range of 15.3-17.6°. The angle between the normals to

the planes of the phenyl ring and the β-diketonate metal ring is 27.3°; the intermolecular F(1)…H(2) contact is 2.29 Å.

Packing of the building blocks in the crystal along the Х axis is given in Fig. 2b. The complexes are linked together

by hydrogen bonds, in which the molecules of coordinated water are involved; the OW…OL and OW…F distances

1088

Fig. 2. Structure of the (CH3)3Pt)(btfa)H2O complex (a) and its molecular packing in the Х axis direction (b).

Fig. 3. Structure of the (CH3)3Pt(bac) Py complex (a) and its molecular packing in the Х axis direction (b).

characterizing these bonds are 2.82 Å and 3.14 Å. In the crystal, the molecules of the complexes are packed with the

minimum Pt…Pt distance of 5.26 Å. The minimum estimate of intermolecular F…F contacts is 3.26 Å.

The structure of II is also of molecular type; it is formed from neutral (CH3)3Pt(bac)Py complexes whose structure

with atomic numbering is given in Fig. 3a. The platinum atom is coordinated by three carbon atoms of methyl groups, two

oxygen atoms of the β-diketonate ligand, and the nitrogen atom of the pyridine molecule; the coordination site (PtC3O2N) has

a form of a slightly distorted octahedron. The deviations of the bond angles from the ideal 90° on the central Pt atom do not

exceed 3.3°. The average Pt–CH3 bond length is 2.035 Å; the Pt–N distance is 2.183 Å. The Pt–Om distance is 2.142 Å; the

O–Pt–O chelate bond angle is 89.1°. In the β-diketonate ligand, the average O–C, C–Cγ, C–CMe, and C–C (in the Ph ring)

bond lengths are 1.264 Å, 1.392 Å, 1.510 Å, and 1.377 Å; the bend angle of the chelate ring along the O…O line is as large

as 10.2°. The phenyl ring plane is turned relative to the metal ring plane by an angle of 27.2°. The average C–N and C–C

bond lengths in the pyridine ligand are 1.330 Å and 1.374 Å respectively. The angle between the normals to the planes of the

β-diketonate and pyridine ligands is 89°. The planes of two triangle faces of the Pt octahedron C3 and O2N are almost

parallel; the angle between these planes is 4.2°.

1089

Fig. 4. Structure of the [(CH3)3PtI]4 complex (a); the crystal structure projection along the [101] direction (b).

Fig. 5. Intermolecular I…I contacts in the structure of [(CH3)3PtI]4.

Packing of the building blocks along the Х axis is shown in Fig. 3b. In the crystal, the molecules of the complexes

are packed with the minimum Pt…Pt distance of 6.802 Å. All pyridine rings of the complexes in the structure are parallel.

The minimum estimate of intermolecular H…H contacts is 2.55 Å.

The crystal structure of [(CH3)3PtI]4 compound III is based on the discrete tetrameric molecules located on a mirror

plane. The molecular structure with atomic numbering is given in Fig. 4a. The platinum and iodine atoms form an almost

regular cube. The deviations of the bond angles on the Pt atoms from the ideal 90° do not exceed 4.3°. The Pt–I–Pt angles are

in a range of 92.52-95.15°. One platinum atom and one iodine atom occupy general crystallographic sites; two others are

located at special sites on the m plane. The coordination sphere of each Pt atom includes 3 iodine atoms and 3 carbon atoms

of the methyl groups forming around platinum a distorted octahedron with the coordination site PtI3C3 having trans

configuration. Each I atom serves as a bridge between two Pt atoms. The Pt–I bond lengths are in a range of 2.7836-2.8287 Å

(the average of 2.8146 Å); the variation of the Pt–C bonds fits in a range of 2.057-2.107 Å with the average of 2.086 Å. The

Pt…Pt and I…I distances within a tetramer are 4.082-4.130 Å and 3.820-3.883 Å respectively.

The projection of the crystal structure on the plane in the [101] direction is given in Fig. 4b. In the crystal, bulk

tetrameric molecules are linked by H bonds of the C–H…I type with the shortest estimates of 3.35-3.58 Å. It is also

noteworthy that the intermolecular I…I contact of 4.17 Å in the structure (Fig. 5) is somewhat less than the sum of van der

Waals radii of iodine being 4.29 Å [21]. The shortest Pt…Pt distances between the molecules are >6.35 Å.

1090

Therefore, in this work, the crystal structure of the metal-organic [(CH3)3PtI]4 complex and two volatile monomeric

chelates of trimethylplatinum(IV) based on phenyl-containing β-diketones with the coordination sites (PtC3O3) and

(PtC3O2N) is determined for the first time. By TG analysis, the comparative estimation of volatility of monomeric β-

diketonates of trimethylplatinum(IV) and their dimeric analogue [(CH3)3Pt(bac)]2 is performed. It is found that the studied

monomeric β-diketonates of trimethylplatinum I and II, as opposed to benzoylacetonate of trimethylplatinum(IV) with the

dimeric structure, exhibit significant volatility and can be used as precursors in chemical vapor deposition for the formation

of platinum films and coatings of different functionality.

REFERENCES

1. T. T. Kodas and M. J. Hampden-Smith, The Chemistry of Metal CVD, VCH, Weinheim, Germany (1994).

2. I. K. Igumenov, J. Physique IV, 5, C5-489-496 (1995).

3. J. R. V. Garcia and T. Goto, Mater. Transact., 44, 1717-1728 (2003).

4. W. J. Pope and F. J. Peachey, J. Chem. Soc., 95, 571-576 (1909).

5. O. M. Ivanova and A. D. Gelman, Zh. Neorg. Khim., 3, No. 6, 1334-1346 (1958).

6. J. C. Baldwin and W. C. Kaska, Inorg. Chem., 14, No. 8, 2020 (1975).

7. R. E. Rundle and J. H. Sturdivant, J. Am. Chem. Soc., 69, No. 7, 1561-1565 (1947).

8. T. G. Spiro, D. H. Templeton, and A. A. Zalkin, Inorg. Chem., 7, No. 10, 2165-2170 (1968).

9. R. Alman and D. Rucharczyk, Zeitschrift fur Kristallographie, 165, Nos. 1-4, 227-232 (1983).

10. K. H. Ebert, W. Massa, H. Donath, J. Lorberth, et al., J. Organom. Chem., 559, 203-209 (1998).

11. Shu-Bin Zhao, Rui-Yao Wang, and Suning Wang, Organometallics, 28, 2572-2582 (2009).

12. A. K. Chatterjee, R. C. Menzies, I. R. Steel, and F. N. Youdale, J. Chem. Soc., No. 4, 1706-1708 (1958).

13. A. G. Swallow and V. R. Truter, Pros. Roy. Soc., 254A, 205-217 (1960).

14. G. I. Zharkova, I. K. Igumenov, and S. V. Zemskov, Koordinats. Khim., 5, No. 5, 743-748 (1979).

15. R. Moshier and R. Sievers, Gas Chromatography of Metal Chelates, Pergamon Press, New York (1965).

16. G. I. Zharkova, I. A. Baidina, D. Yu. Naumov, and I. K. Igumenov, J. Struct. Chem., 52, No. 3, 550-555 (2011).

17. G. I. Zharkova, I. A. Baidina, F. T. Turgambaeva, G. V. Romanenko, and I. K. Igumenov, Polyhedron, 40, 40-45

(2012).

18. Bruker AXS Inc. APEX2 (Version 1.08), SAINT (Version 7.03), SADABS (Version 2.11), SHELXTL (Version 6.12),

Bruker Advanced X-ray Solutions, Wisconsin, Madison, USA (2004).

19. J. R. Hall and G. A. Swile, J. Organometal. Chem., 47, 195-215 (1973).

20. A. D. Cross, An Introduction to Practical Infrared Spectroscopy, London (1960).

21. Yu. V. Zefirov and M. A. Porai-Koshits, J. Struct. Chem., 27, No. 2, 239-244 (1986).