Synthesis of metal complexes with 2-[bis(2-phenylethyl)- thiophophorylhydroxymethyl]-1-organilimidazoles. Crystal structure of ZnCl 2 2L

Article abstract of DOI:10.1134/S1070328408070026

The reactions of Zn(II), Cd(II), Cu(II), Co(II), Pd(II) dichlorides with 2-[bis(2-phenylethyl)thiophosphorylhydroxymethyl]-1-organilimidazoles (L ¹-L⁴) were studied. The novel complexes were synthesized and characterized by IR and NMR spectroscopies. Depending on the nature of imidazolephosphinesulfide, both monodentate (at the pyridine N(1) atom of heterocycle) and the N,S-bidentate binding of the ligand by a metal can be realized in the above metal complexes. The structure of the complex ZnCl ₂ ? 2L⁴(I) (L⁴ = 2-[bis(2-phenylethyl) thiophosphorylhydroxymethyl]-1-ethylbenzimidazole) was studied by X-ray diffraction. One of the two independent L⁴ molecules performs the solvate function, while another one, together with two Cl atoms, is coordinated through the atoms N(1) and S to the Zn atom at the vertices of a slightly distorted tetrahedron. The molecule of the complex is united with the solvate molecule into [ZnCl₂L₄]L⁴ associates by strong intermolecular hydrogen bonds to give nonplanar four-membered H-cycle OH ₂N.

Full text of DOI:10.1134/S1070328408070026

ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2008, Vol. 34, No. 7, pp. 480–492. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © L.V. Baikalova, V.I. Sokol, N.N. Chipanina, N.I. Ivanova, N.K. Gusarova, A.V. Afonin, P.N. Andreev, V.S. Sergienko, B.A. Trofimov, 2008, published in
Koordinatsionnaya Khimiya, 2008, Vol. 34, No. 7, pp. 488–499.
Synthesis of Metal Complexes with 2-[Bis(2-phenylethyl)-
thiophophorylhydroxymethyl]-1-organilimidazoles.
Crystal Structure of ZnCl2 · 2L
L. V. Baikalovaa, V. I. Sokolb, N. N. Chipaninaa, N. I. Ivanovaa, N. K. Gusarovaa,
A. V. Afonina, P. N. Andreeva, V. S. Sergienkob, and B. A. Trofimova
a Irkutsk Institute of Chemistry, Siberian Division, Russian Academy of Sciences, Irkutsk, Russia
b Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences,
Leninskii pr., 31, Moscow, 119991 Russia
E-mail: sokol@igic.ras.ru
Received May 11, 2007
Abstract—The reactions of Zn(II), Cd(II), Cu(II), Co(II), Pd(II) dichlorides with 2-[bis(2-phenylethyl)thio-
phosphorylhydroxymethyl]-1-organilimidazoles (L1–L4) were studied. The novel complexes were synthesized
and characterized by IR and NMR spectroscopies. Depending on the nature of imidazolephosphinesulfide, both
monodentate (at the “pyridine” N(1) atom of heterocycle) and the N,S-bidentate binding of the ligand by a
metal can be realized in the above metal complexes. The structure of the complex ZnCl2 · 2L4 (I) (L4 = 2-[bis(2-
phenylethyl)thiophosphorylhydroxymethyl]-1-ethylbenzimidazole) was studied by X-ray diffraction. One of
the two independent L4 molecules performs the solvate function, while another one, together with two Cl atoms,
is coordinated through the atoms N(1) and S to the Zn atom at the vertices of a slightly distorted tetrahedron.
The molecule of the complex is united with the solvate molecule into [ZnCl2L4]L4 associates by strong inter-
molecular hydrogen bonds to give nonplanar four-membered H-cycle OH2N.
DOI: 10.1134/S1070328408070026
Polydentate ligand systems with N,P,S,O-donor heterylphosphine sulfides are almost unavailable. Only
centers are the least studied objects in coordination
chemistry. The use of the above bases in the metal com-
plex synthesis is restricted, first of all, by the absence of
suitable methods of their preparation. Recently, we
developed technologically effective and atom-saving
method of synthesizing functionalized azoles, i.e.,
2-[bis(2-[phenylethyl)thiophosphorylhydroxymethyl]-
1-organilimidazoles, based on nucleophilic addition of
available secondary phosphine sulfides to 1-organil-2-
formylimidazoles [1]. The derivatives of imidazoles
with thiophosphoryl and hydroxyl substituents, con-
taining donor centers of different nature, play an impor-
tant role in developing the concepts of coordination
two complexes of palladium [13] and indium [14] with
4,5-bis(diphenylthiophosphoryl)-1,2,3-triazole
known.
are
Lately, we have shown that, depending on the accep-
tor nature, 2-(diorganilphospphorylhydroxymethyl]-1-
organilimidazoles can compete in reactions with some
metal chlorides and give molecular or chelate com-
plexes, where the donor-acceptor bond with a metal
involves the heterocyclic N atom and the O atom of the
P=O group of imidazolephosphine oxide [15]. In this
work, in continuation of the study of the complexation
reactions of polydentate imidazolephosphine chalco-
bond, geometry, and structure of complexes, as well as genides, we investigated for the first time the reactions of
in solving the question of regioselective binding of
metal to complexes with polyfunctional ligands. Such
imidazolephosphine sulfides with pharmaceutical
properties are promising compounds not only in design
of biologically active metal complexes [2, 3], but also
in the synthesis of the metal complex catalysts of a new
generation [4], which are also used in the interface
transfer reactions [5].
Zn, Cd, Cu, Co, and Pd dichlorides with 2-[bis(2-phenyl-
ethyl)thiophosphorylhydroxymethyl]-1-vinylimidazole
(L1), 2-[bis(2-phenylethyl)thiophosphorylhydroxyme-
thyl]-1-ethylimidazole (L2), 2-[bis(2-phenylethyl)thio-
phosphorylhydroxymethyl]-1-vinylbenzimidazole (L3),
2-[bis(2-phenylethyl)thiophosphorylhydroxymethyl]-1-
ethylbenzimidazole (L4) with the aim to estimate the
effect of the nature of the chalcogen donor atom and of
the acceptor on the type of coordination of imidazole-
phosphine sulfides L1–L4 to a metal and determine the
The complexes based on the tertiary alkyl- and
arylphosphine sulfides have been reported in [6–12];
however, the data on the complexes with the tertiary properties and structures of the complexes formed:
480

SYNTHESIS OF METAL COMPLEXES
481
MP2/6-31G**//HF/6-31G* method using GAUSSIAN-98
program package [16].
R3
R2
Ph
Ph
N
OH
CH
X-ray diffraction analysis. Crystals of complex I,
ë52ç58Cl2N4O2P2S2Zn (in the form of colorless needles)
belong to monoclinic crystal system. The unit cell
parameters: ‡ = 17.726 (4), b = 18.126 (2), Ò = 16.458 (3) Å,
β = 96.41(6)°, V = 5254.7(2) Å3, ρ(calcd.) =
1.306 g/cm3, µåÓ = 32.3 cm–1, F(000) = 2160, M =
1033.35, Z = 4, space group ê21/c.
The experimental data set was obtained from a sin-
gle crystal at room temperature on automated four-cir-
cle CAD-4 Enraf-Nonius diffractometer (graphite
P
S
N
R1
L1: R1 = CH=CH2; R2 = R3 = H
L2: R1 = C2H5; R2 = R3 = H
L3: R1 = CH=CH2; (R2 + R3) = (CH)4
L4: R1 = C2H5; (R2 + R3) = (CH)4
EXPERIMENTAL
monochromator, CuKα radiation, ω scan mode, 2θm‡ı
=
120°). The total of 7386 reflections was registered
Synthesis of complexes of ZnCl2 and CdCl2 with
ligands L1–L4. The calculated amounts of the ligand
and salt were mixed in acetone at 20–25°ë and in 8 h,
compounds of the white color were precipitated using
the following solvents: ether (Zn complex with L1 and
Cd complexes with L1–L4), hexane (Zn complexes with
L2–L4). The precipitates were filtered, washed with the
(Rint = 0.035, 0 ≤ h ≤ 19, –24 ≤ k ≤ 0, –12 ≤ l ≤ 18).
The structure was solved by the direct method
(SHELXL-97)[17] and refined by the least-squares
method in full-matrix anisotropic approximation (on
F2) for non-hydrogen atoms (SHELXL-97) [18]. The
hydroxyl hydrogen atoms were localized from the Fou-
corresponding mixture acetone–ether (1 : 1) or ace- rier difference synthesis and refined isotropically. The
tone–hexane (1 : 1), and dried in vacuum.
positions of the hydrogen atoms at the C atoms were
calculated geometrically (C−H 0.96 Å) and included in
refinement with fixed geometrical and thermal parame-
ters UH, which are 0.1–0.3 Å2 larger than the Uj param-
eters of the corresponding C atoms. The final refine-
ment parameters: R1 = 0.043, wR2 = 0.077 for 1541
reflections with Fo ≥ 4σ(Fo); R1 = 0.385, wR2 = 0.143 for
all reflections; GOOF = 0.918. The maximum and min-
imum residual densities are 0.118 and 0.017 Â Å3, the
extinction coefficient is equal to 0.0000(5).
Synthesis of PdCl2 complexes with ligands L1–L4.
The calculated amounts of the ligand and salt were
mixed in a boiling acetone for 8 h. The complex com-
pounds of the bright brown color were precipitated
from the reaction mixture with dry ether, filtered,
washed with ether, and dried in vacuum.
Synthesis of CuCl2 complexes with ligands L1, L4
and CoCl2 complexes with L1. The calculated
amounts of the ligand and salt were mixed in acetone
for 24 h at 20–25°ë (Cu and Co complexes with L1) and
in ethanol (Cu complex with L4). The complexes of
mustard (Cu complexes) and blue (Co complexes)
color precipitated with ether from the reaction mixture
were filtered, washed with ether, and dried in vacuum.
The coordinates and thermal parameters of the
atoms in complex I are listed in Table 2, the main bond
lengths and bond angles are given in Table 3.
RESULTS AND DISCUSSION
The results of the elemental analysis and some phys-
icochemical properties of the title metal complexes are
given in Table 1.
A single crystal of the complex bis{2-(2-phenyl-
ethyl)thiophosphorylhydroxymethyl]-1-ethylbenzimi-
dazole}dichlorozinc, [ZnCl2 · 2L42 ] (I) suitable for
X-ray diffraction analysis was obtained by recrystalli-
zation of [ZnCl2 · L4] from ethanol.
In this work, the reaction of investigated imidazole-
phosphine sulfides L1–L4 with metal dichlorides was
performed in anhydrous solvents (acetone, ethanol) at a
ratio of the starting components 1 : 1, 4L : 1, and 2L : 1.
As a result, the complexes of the composition 1 : 1 were
obtained, except for the compounds ZnCl2 · 2L2 and
ëuCl2 · 2L4. Complexes based on imidazolephosphine
sulfides L1, L2 were formed in 43–98% yield (Table 1).
The complexes of Cd with imidazolephosphine sulfides
L1–L4 were obtained with the maximum yield (~98%),
the yield of the complexes of Zn with L1–L4 and Co
with L1 was 85–95%, whereas the complexes with the
analogous composition 1 : 1 with imidazolephosphine
oxides were formed in a lower yield (48−73%) [15].
The ëuCl2 · L1 and ëuCl2 · 2L4 complexes were
obtained with the yield 49 and 54%, respectively. The
The IR spectra of the synthesized complexes were
recorded on a IFS 25 Bruker spectrometer using KBr
pellets and Nujol.
1
The H NMR spectra of solutions of complexes in
ëDël3 and DMSO-d6 were measured on a DPX-400
Bruker spectrometer at room temperature with HMDS
as internal standard.
The quantum-chemical calculations of mole- elevation of the reaction temperature to 70–80°ë was
cules and their vibration spectra were performed by found to cause the decomposition of imidazolephos-
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SYNTHESIS OF METAL COMPLEXES
483
Table 2. The atomic coordinates and thermal parameters Ueq in structure I
Atom
Zn(1)
x
y
z
Ueq, Å2
Atom
x
y
z
Ueq, Å2
0.7813(1)
0.7961(2)
0.7933(2)
0.7147(2)
0.6679(2)
0.7671(3)
0.795(3)
0.1596(1) 0.9700(1) 0.0544(5) C(26)
0.9875(6) 0.2519(6) 1.3048(6) 0.075(4)
0.7585(2) –0.4385(2) 1.1761(2) 0.061(1)
0.8081(2) –0.3527(2) 1.1365(2) 0.073(1)
0.7915(4) –0.5700(4) 1.2477(4) 0.078(3)
Cl(1)
Cl 2)
P(1)
0.2362(2) 0.8674(2) 0.085(1)
0.0405(2) 0.9335(2) 0.081(1)
P(1B)
S(1B)
0.1938(2) 1.1418(2) 0.0452(9) O(1B)
S (1)
O(1)
0.1758(2) 1.0286(2) 0.63(1)
0.3148(3) 1.0902(4) 0.054(2)
H(1B)
N(1B)
N(2B)
C(1B)
0.786
–0.597
1.214
0.17(3)
0.8687(5) –0.5773(5) 1.1061(6) 0.048(3)
0.9576(6) –0.5055(5) 1.1707(5) 0.042(3)
0.8837(7) –0.5294(6) 1.1640(7) 0.044(3)
0.9937(8) –0.5435(6) 1.1112(6) 0.039(3)
0.9510(7) –0.6314(6) 1.0090(7) 0.052(4)
1.0244(8) –0.6338(6) 0.9900(7) 0.060(4)
1.0811(7) –0.5897(7) 1.0282(7) 0.060(4)
1.0679(6) –0.5421(6) 1.0899(7) 0.054(4)
0.9360(8) –0.5867(6) 1.0718(7) 0.040(3)
0.8293(6) –0.5062(6) 1.2238(7) 0.058(4)
0.6922(6) –0.4869(6) 1.1044(7) 0.081(4)
0.7064(8) –0.4856(7) 1.0175(9) 0.105(5)
0.6470(1) –0.530(2) 0.9628(9) 0.099(6)
H(1)
0.368(4) 1.085(3)
0.02(2)
N(1)
0.8678(5)
0.9352(6)
0.8655(7)
0.9870(7)
1.0653(7)
1.0978(7)
1.0548(8)
0.9785(7)
0.9439(7)
0.7938(5)
0.7516(5)
0.6910(6)
0.1807(5) 1.0573(5) 0.045(3)
0.2395(5) 1.1602(5) 0.041(3)
0.2245(6) 1.1206(8) 0.039(3)
0.2019(6) 1.1179(8) 0.042(3)
0.1966(6) 1.1299(7) 0.062(4)
0.1532(7) 1.0738(8) 0.068(4)
0.1168(7) 1.0107(7) 0.073(4)
0.1225(6) 0.9998(6) 0.056(4)
0.1657(6) 1.0555(7) 0.40(3)
0.2591(5) 1.1455(6) 0.036(3)
0.1117(5) 1.1926(5) 0.050(3)
0.0502(7) 1.1969(7) 0.093(4)
N(2)
C(2B)
C(1)
C(3B)
C(2)
C(4B)
C(3)
C(5B)
C(4)
C(6B)
C(5)
C(7B)
C(6)
C(8B)
C(7)
C(9B)
C(8)
C(10B)
C(11B)
C(12B)
C(13B)
C(14B)
C(15B)
C(16B)
C(17B)
C(18B)
C(19B)
C(20B)
C(21B)
C(22B)
C(23B)
C(24B)
C(25B)
C(26B)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(19)
C(20)
C(21)
C(22)
C(23)
C(24)
C(25)
0.6450(1) –0.603(1) 0.951(1)
0.113(7)
0.7261(6) –0.0239(7) 1.2060(1) 0.059(4)
0.7401(8) –0.061(1) 1.1390(1) 0.099(5)
0.7710(1) –0.1310(1) 1.1400(1) 0.110(6)
0.7905(9) –0.1590(1) 1.2170(2) 0.113(7)
0.7810(1) –0.1260(1) 1.2880(1) 0.124(7)
0.7484(9) –0.0570(1) 1.2820(1) 0.094(5)
0.5900(1) –0.6380(9) 0.9000(1) 0.113(6)
0.5374(9) –0.597(2) 0.8560(9) 0.106(7)
0.5340(1) –0.522(1) 0.864(1)
0.5890(1) –0.4891(9) 0.917(1)
0.122(9)
0.117(7)
0.7077(7) –0.4194(6) 1.2635(7) 0.103(6)
0.6747(9) –0.3550(8) 1.2714(9) 0.168(8)
0.6422(9) –0.3329(9) 1.3500(9) 0.084(5)
0.6747(8) –0.2796(8) 1.3990(1) 0.099(5)
0.6400(1) –0.258(1) 1.4660(1) 0.126(7)
0.5770(1) –0.294(1) 1.4850(1) 0.13(1)
0.5469(8) –0.348(1) 1.4360(1) 0.108(6)
0.5780(1) –0.3676(7) 1.3680(9) 0.103(5)
0.9980(6) –0.4589(6) 1.2329(8) 0.064(4)
1.0358(7) –0.4993(6) 1.3058(7) 0.102(5)
0.6464(5)
0.6141(6)
0.5644(8)
0.4882(8)
0.4435(8)
0.4780(1)
0.5530(1)
0.5966(7)
0.9579(6)
0.2334(5) 1.2042(5) 0.044(3)
0.3082(6) 1.1756(6) 0.065(4)
0.3396(6) 1.2353(8) 0.053(4)
0.3274(6) 1.2279(7) 0.076(4)
0.3587(8) 1.2840(1) 0.095(5)
0.3998(9) 1.3442(9) 0.090(6)
0.4160(7) 1.3556(8) 0.086(5)
0.3824(7) 1.2977(9) 0.070(4)
0.2902(6) 1.2288(8) 0.067(4)
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BAIKALOVA et al.
Table 3. The bond lengths and bond angles in structure I
Molecule L4C
Molecule L4S
Bond
Angle
ω, deg
d, Å
Zn(1)–Cl(1)
Zn(1)–Cl(2)
2.224(3)
2.258(3)
C(9)P(1)C(17)
Zn(1) S(1)P(1)
107.4(4)
97.1(1)
105.5(5)
111(3)
Zn(1)–S(1)
Zn(1)–N(1)
P(1)–S(1)
2.343(3)
2.017(9)
1.977(4)
1.84(1)
1.798(9)
1.813(9)
1.41(1)
1.31(2)
1.38(2)
1.36(2)
1.39(2)
1.48(2)
1.51(2)
1.38(2)
1.38(2)
1.40(2)
1.56(2)
1.48(3)
1.52(1)
1.50(2)
1.48(2)
H(1)O(1)C(8)
Zn(1)N(1)C(1)
Zn(1)N(1)C(7)
C(1)N(1)C(7)
C(1)N(2)C(2)
C(1)N(2)C(25)
C(2)N(2)C(25)
N(1)C(1)N(2)
N(1)C(1)C(8)
N(2)C(1)C(8)
N(2)C(2)C(3)
N(2)C(2)C(7)
C(3)C(2)C(7)
C(2)C(3)C(4)
C(3)C(4)C(5)
C(4)C(5)C(6)
C(5)C(6)C(7)
N(1)C(7) C(2)
N(1)C(7) C(6)
C(2)C(7)C(6)
P(1)C(8)O(1)
124(3)
126.3(8)
127.9(7)
104.6(9)
106.0(1)
130.0(1)
123.3(9)
113.0(1)
124.0(1)
122.0(1)
132.0(1)
105.0(1)
123.0(1)
115.0(1)
122.0(1)
122.0(1)
118.0(1)
111.0(1)
129.0(1)
121.0(1)
103.8(6)
113.0(7)
1.935(4)
1.87(1)
1.80(1)
1.81(1)
1.41(1)
1.29(2)
1.39(2)
1.37(2)
1.41(2)
1.45(2)
1.51(2)
1.40(2)
1.39(2)
1.39(2)
1.48(2)
1.54(3)
1.32(1)
1.53(2)
1.50(2)
P(1)–C(8)
P(1)–C(9)
P(1)–C(17)
P(1)–C(8)
N(1)–C(1)
N(1)–C(7)
N(2)–C(1)
N(2)–C(2)
N(2)–C(25)
C(1)–C(8)
C(2)–C(3)
C(2)–C(7)
C(6)–C(7)
C(9)–C(10)
C(10)–C(11)
C(17)–C(18)
C(18)–C(19)
C(25)–C(26)
105.5(9)
107.1(9)
129.0(1)
123.2(9)
113.0(1)
125.0(1)
122.0(1)
133.0(1)
103.0(1)
124.0(1)
116.0(1)
124.0(1)
122.0(1)
115.0(1)
111.0(1)
129.0(1)
120.0(1)
109.7(7)
Angle
ω, deg
P(1)C(8)C(1)
110.9(8)
Cl(1)Zn(1)Cl(2)
Cl(1)Zn(1) S(1)
111.8(1)
114.4(1)
O(1)C(8)C(1)
110.7(8)
113.2(7)
112.0(1)
119.0(1)
124.0(1)
115.2(7)
111.3(9)
122.0(1)
119.0(1)
113.4(9)
108.0(9)
117.2(9)
P(1)C(9)C(10)
Cl(1)Zn(1)N(1)
Cl(2)Zn(1)S(1)
Cl(2)Zn(1)N(1)
S(1)Zn(1)N(1)
S(1)P(1)C(8)
S(1)P(1)C(9)
S(1)P(1)C(17)
C(8)P(1)C(9)
C(8)P(1)C(17)
106.1(3)
109.9(1)
106.5(3)
107.6(3)
112.0(3)
113.2(3)
111.6(3)
105.9(4)
106.3(4)
C(9)C(10)C(11)
C(10)C(11)C(12)
C(10)C(11)C(16)
P(1)C(17)C(18)
C(17)C(18)C(19)
C(18)C(19)C(20)
C(18)C(19)C(24)
N(2)C(25)C(26)
112.0(1)
127.0(2)
116.0(2)
121.0(1)
122.0(1)
121.0(1)
118.0(1)
114.9(9)
111.2(4)
117.4(4)
113.4(4)
108.4(5)
99.4(5)
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SYNTHESIS OF METAL COMPLEXES
485
phine sulfides L1–L4 to the starting fragments, i.e., imi- cules L1–L4 and the model calculations—2-[bis(2-
dazolecarbaldehydes and phosphine sulfides. The reac- methyl)-thiophosphorylhydroxymethyl]-1-methylimi-
tion products also contained complexes with the corre- dazole (L) and 1-vinyl-2-hydroxymethylimidazole
(L5).
To determine the conformations of L1–L4 molecules,
the model ligand L was calculated and the minima on
the potential energy surface were found to correspond
to three conformation isomers: with intramolecular
hydrogen bonds (IHB) OH···N (La), OH···S=P (Lb), and
with a free HO group (Lc):
sponding 1-ethyl(vinyl)imidazolecarbaldehydes. The
analogous reaction of ëuCl2 with the ligands L2, L3
occurs even without heating.
The types of coordination of polydentate imidazole-
phosphine oxides to the metal atoms were proposed by
us on the basis of the spectral data (IR, 1H NMR) and
theoretical calculations of free and coordinated mole-
S
CH3
CH3
CH3
N
N
CH3
CH3
N
OH
CH
P
S
P
P
S
CH3
CH
HO
(Lb)
CH
OH
N
N
N
CH3
CH3
CH3
(La)
(Lc)
17 cm–1 at insignificantly changing frequency (∆ν =
4 cm–1) of the stretching vibrations of the heterocycle.
The above change in the vibration frequencies agrees
with the observed shifts of IR bands of the synthesized
As in the case with the oxygen analog of imidazole-
phosphine oxide [15], the most stable among conform-
ers L‡,b,c, according to the calculation data, is the L‡
conformer with a strong IHB O−H···N between the
hydroxyl group and the “pyridine” N atom of imidazole complexes as compared with free imidazolephosphine
sulfides L1–L4.
ring. The conformer Lb with the IHB OH···S=P is ener-
getically less favorable than the isomer L‡ (by
Thus, in IR spectra of Zn, Cd, Cu, and Co com-
plexes with 1-vinyl- and 1-ethylimidazolephosphine
sulfides (L1, L2) and Pd complexes with benzimidazole
ligands L3, L4, a short-wave shift (by 15−20 cm–1) of the
absorption bands due to the stretching vibrations of
imidazole ring was observed at 1480−1520 cm–1 as
compared to the ligands themselves, as in the case of
hydrochloride molecules L1–L4 [1], which suggests the
4.00 kcal/mol). The minimum stability (∆Ö
=
8.74 kcal/mol) is shown by the Lc conformer with a free
hydroxyl group.
The calculation of the normal vibrations of isomers
L and their complexes with ZnCl2 was performed with
the aim to qualitatively estimate the change in the
vibration frequencies of the functional groups, which
can participate in the formation of the coordination or
hydrogen bonds. It was shown that the stretching vibra-
tions of free OH and P=S groups in the L ligand are
characterized by the calculated frequencies 4076 and
625 cm–1, respectively, while the stretching vibrations
of the azole ring, by the frequencies 1740, 1680 cm–1.
For L conformers with IHB éç···N=C and éç···S=ê,
the frequency of the stretching vibration of the O−H
bond is 60 and 75 cm–1 lower than ν(éç) of a free
hydroxyl group, respectively. The value ν(P=S) also
decreases (by 18 cm–1), while the stretching vibration
of a heterocycle undergo shifts, both a long-wave shift
by 8 cm–1 (the high-frequency vibration 1740 cm–1) and
a short-wave shift by 10 cm–1 (the low-frequency vibra-
tion 1680 cm–1). The coordination with the participa-
tion of the S atom in zinc chloride complexes with all L
formation of the N
M bond in the above com-
pounds. However, the heterocycle vibration frequen-
cies in the complexes of Zn, Cd with benzimidazole-
phosphine sulfides L3, L4 and copper with L4 remain
unchanged (1478, 1483, 1496, 1520 cm–1). At the same
time, in the spectra of the above complexes, the maxi-
mum of a doublet band (550–568 cm–1) due to the
stretching vibrations of the P=S group is lowered by
6−17 cm–1, while in the spectra of the Zn and Cd com-
pounds with imidazolephosphine sulfide L3, the indi-
cated absorption band position remains almost
unchanged. A small shift of the band ν(P=S) is caused,
in our opinion, by the formation of the éç···S bond
upon the change in the ligand conformation in a com-
plex, which agrees with the calculated data. Note that
the coordination of the tertiary alkyl- and arylphos-
isomers reduces the value ν(P=S) by 18 cm–1, while that phine sulfides and of imidazolidine-2-thiones to Lewis
with the participation of the N atom increases the fre- acids is attended by the formation of the molecular
quency of the stretching vibration of the azole ring by complexes with the S
å coordination bond, whose
spectra exhibit considerable lowering of the stretching
~10 cm–1. When the Zn atom forms the chelate ring
closed by the coordination bonds S
Zn
N (the vibrations due to the P=S group from 20 to 60 cm–1
1 : 1 complex), the value ν(P=S) also decreases by [10, 19].
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 7 2008

486
BAIKALOVA et al.
Table 4. The chemical shisfts (δ, ppm) of the protons in 1H NMR spectra (CDCl3) of free and coordinated imidazolephos-
H
*
A
phine sulfides L1–L4,
Het CH
C
X
H
B
Compound
L1**
HX(q)
HA(d)
HB(d)
HCH(OH)(s)
5.36
HCH (m)
HCH (t)
H4, 5
2
3
7.46
4.87
5.42
7.70, 7.02
[PdL1Cl2]** 7.62 (–0.17) 5.39 (–0.52) 5.94 (–0.52) 6.13 (–0.77)
8.33, 7.87
(–0.63, 0.85)
L2
4.94
4.16
1.38
6.98, 6.92
7.11, 6.93
(–0.13, 0.01)
[ZnL2 Cl2]
5.92 (–0.98) 4.36 (–0.20) 1.42 (–0.04)
2
[PdL2Cl2]
5.61 (–0.67) 4.38 (–0.22) 1.42 (–0.04) 7.41, 6.98
(–0.43, 0.06)
L2**
5.17
4.09
1.33
6.98, 6.92
[ZnL2Cl2]**
5.44(–0.27) 4.22 (–0.13) 1.31(+0.02) 7.32, 6.99
(–0.34, –0.07)
[CdL2Cl2]**
5.39(–0.22) 4.25 (–0.66) 1.31(+0.02) 7.32, 6.99
(–0.34, –0.07)
L3
7.45
5.33
5.53
5.16
[ZnL3Cl2]
[PdL3Cl2]
L4
7.47 (–0.02) 5.57 (–0.24) 5.61 (–0.08) 5.54 (–0.38)
7.73 (–0.28) 5.69 (–0.36) 5.95 (–0.42) 5.84 (–0.68)
5.08
4.38
1.31
[PdL4Cl2]
L5**
5.57 (–0.49) 4.53 (–0.15) 1.51 (–0.20)
4.54
7.24
4.88
5.43
7.61, 6.90
[ZnL5 Cl2]**
7.28 (–0.04) 5.07 (–0.19) 5.63 (–0.20) 4.73 (–0.19)
7.82, 7.06
2
(–0.21, –0.16)
Note: *The direction and value of the shift of a proton signal in the complexes against the corresponding ligand are given in parentheses:
(–) downfield shift, (+) upfield shift.
**The spectra of compounds were recorded in DMSO-d .
6
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 7 2008

SYNTHESIS OF METAL COMPLEXES
487
C(21)
C(22)
C(23)
C(24)
C(20)
C(19)
C(18)
C(14B)
C(23B)
C(15B)
C(13B)
C(22B)
C(24B)
C(16B)
C(9B)
C(10B)
C(21B)
C(20B)
C(13)
S(1)
C(17)
C(12B)
C(18B)
C(17B)
C(11B)
C(19B)
C(10)
C(11)
C(16)
P(1)
C(12)
O(1)
C(9)
P(1B)
C(15)
O(1B)
C(8B)
Zn(1)
N(1)
C(7)
C(14)
C(8)
Cl(2)
Cl(1)
S(1B)
N(1B)
C(1)
N(2)
C(1B)
N(2B)
C(7B)
C(25)
C(6B)
C(5B)
C(6)
C(5)
C(2)
C(3)
C(25B)
C(2B)
C(26B)
C(26)
C(4B)
C(3B)
C(4)
4C
4S
Fig. 1. The structure of molecules ZnCl L and L in complex I.
2
The comparative analysis of the stretching vibra- atom of a heterocycle and leads to the change in the
ligand molecule conformation resulting in the forma-
tion of intramoleular and intermolecular hydrogen
bonds éç···S and éç···éç, respectively. The experi-
mental and calculation data for the Zn, Cd, Cu com-
plexes based on the ligands L3 and L4 do not exclude
also the formation of the chelate complex with
N,S-bidentate binding of a metal. The calculations
tions of the OH groups in IR spectra of imidazolephos-
phine sulfides L1–L4 and their complexes indicates also
the change in the type of hydrogen bonds in imidazole-
phosphine sulfides on their binding with the electron-
acceptor. In the spectra of the complexes, the absorp-
tion bands ν(éç) of the hydroxyl group associated
with the N atom of a heterocycle undergo a high-fre-
quency shift (3150−3300 cm–1) as compared with the
bands in the spectra of free ligands (3130−3150 cm–1).
The highest shift (up to 3326 cm–1) was observed for
the Zn complexes, which indicates association of the
éç···éç type. The analogous absorption band in the
spectra of the Cd, Cu, Co, and Pd complexes lies within
3150−3240 cm–1, which can be explained by the forma-
tion of intermolecular hydrogen bond éç···S. IR spec-
tra of solutions of the Pd and Zn complexes of imida-
zolephosphine sulfides L1 and L2 (in ëçCl3, ëCl4) con-
tain a broad absorption band with maxima at 3200 and
3607 cm–1 (PdCl2 · L1) and 3270, 3490, and 3608 cm–1
revealed that both chelate with the distances N
Zn
2.160 and S
Zn 2.567 Å and the molecular com-
plex with the coordination center at the N atom (N
Zn 2.041 Å) have equal energy of formation.
1
The H NMR structural study of complexes based
on imidazolephosphine sulfides L1–L4 also showed the
possibility of formation of compounds with both mon-
odentate (at the N atom of a heterocycle) and N,S-bi-
dentate metal coordination. Thus, the analysis of the
1H NMR spectra of solutions of the Zn, Cd, Pd com-
plexes, measured due to the limited solubility not only
in ëDCl3 but also in DMSO-d6, indicated essential
changes as compared to the spectra of free molecules
L1–L4 (Table 4). The exceptions were the adducts of
zinc with imidazolephosphine sulfides L1, L4 and of
cadmium with L1, L3, L4 (in DMSO-d6), whose spectra
are similar to those of unbonded ligand molecules,
which suggests their complete dissociation in a solu-
tion. As compared to 1H NMR spectra of free ligands,
the spectra of the remaining complexes exhibit down-
field shifts of the proton signals of a heterocycle and
substituents in positions 1 and 2 of the azole ring
(Table 4). The shift of a signal of the proton CH of the
hydroxymethyl group in different compounds differs
considerably. In the spectra of [ZnL2Cl2], [CdL2Cl2],
(ZnCl2 · L2). In the spectra of strongly diluted solutions
of these complexes, the low-frequency components
(3200 and 3270 cm–1) disappear, while the bands due to
the IHB ν(OH···S) and a free ν(éç) with the corre-
sponding frequencies 3490 and ~3610 cm–1 remain
unchanged.
The indicated changes in the characteristic absorp-
tion frequencies of the functional groups in IR spectra
of the synthesized complexes with account of the calcu-
lated vibration spectra of the conformation isomers L
and their complexes suggest that the coordination of
imidazolephosphine sulfides L1–L4 with a metal gives
the complexes with the donor–acceptor bond at the N
and [PdL3Cl2], this shift (∆δ) lies in the interval
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 7 2008

488
BAIKALOVA et al.
Table 5. The geometric parameters of hydrogen bonds between the molecules L4C and L4S in structure I
Distance, Å
Equivalent posi-
tion of atom Y
Bond X–H···Y
Angle (XHY), deg
X–H
H···Y
X···Y
O(1B)–H(1B)···O(1)
O(1B)–H(1B)···N(1B)
O(1)–H(1)···N(1B)
0.74(3)
0.74(3)
1.09(3)
2.58(2)
2.47(3)
1.65(3)
3.319(9)
2.833(9)
2.652(9)
175(3)
114(2)
151(2)
x, 1 + y, z
x, y, z
x, 1 + y, z
complex [ZnCl2L4C] · L4S. Both donor centers of imida-
0.38−0.22 ppm and is close to the shift (∆δ ≈ 0.2 ppm)
zolephosphine sulfide L4C (the “pyridine” nitrogen
atom N(1) and the S atom) participate in a metal coor-
dination. The L4C ligand in the complex is bidentate-
chelate and its addition closes a six-membered metallo-
ring.
(Table 4) in the spectrum of a model compound
[ZnL52 Cl2] (L5 = 1-vinyl-2-hydroxymethylimidazole)
with coordination exactly at the N3 atom of a heterocy-
cle [20, 21]. On the contrary, in the spectra of
[PdL1Cl2], [ZnL22 Cl2], [PdL2Cl2], [PdL3Cl2], and
The Zn atom is coordinated at the vertices of a
slightly distorted tetrahedron by the N(1) and S(1)
atoms of the ligand L4C and by two chlorine atoms
(Cl(1) and Cl(2)). The smallest angles in the tetrahe-
dron are the endocyclic angle SZnN (107.6(3)°) and the
[PdL4ël2], a signal of the CH(OH) proton shows more
substantial shift (∆δ = 0.98−0.49 ppm) (Table 4). The
observed downfield shift of a signal of the CH(OH)
proton in the given complexes can be explained by the
formation of the chelate rings in the structure with the
participation of heteroatoms S and N. In this case, the
additional downfield shift of a signal of the proton
∆δëç(éç) is due to both the effect of the metal coordina-
tion with the S atom and the effect of a central atom on
the CH proton.
angles ClZnN (106.3(3)°
0.2°), while the angles
ClZnS (112.2(1)° 2.3°) have the largest values. The
bonds Zn–S 2.343(3), Zn–Cl (1) 2.224(3) and Zn–N
2.017(9) Å have common lengths. The bond Zn–Cl(2)
2.258(3) Å is slightly elongated, possibly, due to the
short intermolecular contact (Cl(2)···H(17B) 2.93,
Cl(2)···C(17B) 3.742 Å; the angle Cl(2)H(17B)C(17B)
141°).
The structure of complex I was determined by X-ray
diffraction (Fig. 1) and is peculiar in the presence of
two independent molecules L4; one of them (L4C) is
involved in the coordination sphere of the Zn atom and
another one (L4S) performs the solvate function in the
The chelate cycle ZnSPC2N is noticeably nonplanar
(∆av
= 0.152 Å), the maximum deviations from its
mean plane being observed for the atoms P(1)
(−0.452 Å) and C(8) (+0.462 Å). the conformation of
the above six-membered metallocycle can be most ade-
quately described as a strongly distorted asymmetric
boat: the atoms N(10 and P(1) deviate toward one side
by 0.318 and 0.792 Å, respectively, from the mean
plane of the atoms Zn(1)S(1)C(1)C(8) (∆av = −0.13 Å).
Table 6. The main torsion angles in structure I
ϕ deg
Angle
molecule L4C
molecule L4S
The independent molecules L4C and L4S in complex
I have substantially different conformations. The sol-
vate molecule L4S is in the cis-form (La) with a strong
intramolecular hydrogen bond é(1Ç)–ç(1Ç)···N(1B)
Table 5. The O(1B) atom is cis to the N(1B) atom and
trans to the S(1B) atom (the corresponding torsion
angles are equal to 41.3° and –176.6°) (Table 6). In the
process of complex formation, the molecule L4 confor-
mation changes noticeably: when the N(1) atom enters
the coordination sphere of Zn atom, the intramolecular
hydrogen bond éç···N in L4S is ruptured, while the
1-ethyl-2-hydroxymethylbenzimidazole fragment in
the L4C ligand is rotated through ~130° about the
P(1)−C(8) bond as compared with the solvate molecule
S(1)P(1)C(8)O(1)
S(1)P(1)C(8)C(1)
43.4
–76.6
–179.7
156.5
–71.8
104.6
–61.4
–73.6
–176.6
–57.3
–170.4
179.0
41.3
C(19)C(18)C(17)P(1)
C(11)C(10)C(9)P(1)
O(1)C(8)C(1)N(1)
O(1)C(8)C(1)N(2)
S(1)P(1)C(17)C(18)
C(2)N(2)C(25)C(26)
–133.1
33.2
–81.7
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 7 2008

SYNTHESIS OF METAL COMPLEXES
489
C(1)
N(1)
C(7)
N(2)
C(2)
C(6)
C(5)
C(3)
C(4)
4C
4S
Fig. 2. The overlap of molecules L (solid line) and L (dashed line) with coinciding benzimidazole fragments in structure I.
L4C. As a result, the L4C molecule becomes the trans-
isomer (Lb). The atom O(1) transforms from the cis- to
the trans-position relative to the atom N(1) (the torsion
angle O(1)C(8)C(1)N(1) in the ligand L4C increases to
−71.8° and changes its sign) and, conversely, from the
trans- to the cis-position relative to the S(1) atom (the
torsion angle S(1)O(1)C(8)O(1) in the ligand L4C
decreases with the change in the sign as compared to
the L4C molecule from −176.6° to 43.4°) (Table 6).
The molecule of the [ZnCl2L4C] complex (x, y, z)
and the solvate molecule L4S (x, 1 + y, z) in compound
I are united by strong intermolecular hydrogen bonds
between the N and O atoms into [ZnCl2L4C] · L4S asso-
ciates (Fig. 3). The atoms O(1) (x, y, z) and O(1B)
(x, 1 + y, z) form three intermolecular hydrogen bonds,
i.e., é(1)−ç(1)···N(1B), é(1Ç)−ç(1Ç)···é(1) and
é(1Ç)−ç(1Ç)···N(1B) bonds (Table 5). As a result of
the above interactions, two nonplanar H cycles conju-
gated at the bond N(1BA)−H(1B) are closed: the four-
membered éç2N with the distance between the atoms
H 2.24 Å and the five-membered OHNC2 cycles. The
deviations of the atoms from the mean plane of the first
cycle O(1)H(1)H(1B)N(1B) (∆ = 0.107°) are: O(1)
0.129, H(1) −0.21, H(1B) −0.01, and N(1B) 0.08 Å. the
five-membered H-cycle is distorted almost to the same
extent (∆ = 0.110 Å); the atomic deviations from the
mean plane O(1B)H(1B)N(1B)C(1B)C(8B) are: O(1B)
0.09, H(1B) 0.02, N(1B) 0.091, C(1B) 0.180, C(8B)
0.169 Å. the five-membered cycle has a strongly dis-
torted sofa conformation: the atoms C(1B) and O(1B)
deviate to one side from the plane N(1B)C(8B)H(1B)
by 0.347 and 0.154 Å, respectively.
In addition, two L4 molecules have significantly dif-
ferent orientation of benzene rings, obviously due to
intermolecular π−π-, d−π-interactions between the L4C
and L4S molecules in crystal I. As a result, the dihedral
angles between the planes of benzimidazole (Ä) and
aromatic rings C(11)–C(16) (Ç), C(19)–C(24) (B') in
the molecule L4S (A/B 20°,A/B' 116°, and B/B 97°) and
in the ligand L4C (A/B 13°, A/B' 64°, and B/B' 75°) dif-
fer considerably. The ethyl substituents retain their
positions relative to the benzimidazole fragment on the
rotation of the latter. The changes observed in the L4
molecule during complex formation are shown in
Fig. 2, where the ligands L4C and L4S are superimposed,
provided that the C atom of benzimidazole fragments
coincide.
The majority of analogous bond lengths in the mol-
ecules L4C and L4S are almost equal (Table 4), but in the
L4C ligand, as a rule, the bonds to the atoms coordinated
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 7 2008

490
BAIKALOVA et al.
S(1)
O(1BA)
P(1)
O(1)
Cl(1)
N(1BA)
Zn(1)
Cl(2)
4C
4S
Fig. 3. The structure of associate [ZnCl L ] · L in complex I.
2
fragments C(2B)−C(7B) of the L4S molecule at the
with a metal are slightly elongated. In particular, the
bond P−S bond in the L4C molecule (1.977(4) Å) is inversion center (0, 0, 0) on one side and between the
C(19)−C(24) cycles in L4C at the inversion center (1/2,
noticeably (by 0.042 Å) longer than the analogous bond
in L4S (1.935(4) Å). Also, the N(1)−C(1) bond in the 0, 1/2) on the other side. The extent of overlap of the
L4C ligand is somewhat elongated (1.31(2) Å) as com-
pared to the L4S molecule (1.29(2) Å). The P(1)–C(9)
and P(1)–C(17) bond lengths in the molecule L4C (av.
(1.806(9) 0.011 Å)) almost did not change as com-
pared to the analogous bonds in L4S (1.805(10)
0.005 Å). The bonds C-OH in the carboxyl groups of
L4C and L4S have equal lengths (1.41(1) Å) close to the
standard value [22].
contacting plane-parallel cycles at the inversion center
(0, 0, 0) is shown in Fig. 5. The cycles at the other inver-
sion center show almost the same overlap; the distances
between their planes (3.30 and 3.50 Å) are typical of
such interactions [24]. The phenyl cycles B and B' that
are perpendicular to the extension of associates (at the
inversion center (1/2, 0, 0) do not participate in the
interaction; the distance between their planes >4 Å. The
shortened contacts Cl(2)···O(1B) (3.101 Å) are formed
between the columns.
In the structural units of crystal I, which are the
bulky molecular associates [ZnCl2L4C] · L4S (Fig. 3),
the periphery space is formed on one side by two benz-
imidazole fragments, and on the other side, by three
phenyl rings. The fourth phenyl cycle of the associate is
almost perpendicular to its extension. The associate
packing in crystals (projection on the plane xz) is shown
in Fig. 4. The associates are extended between two
inversion centers (0, 0, 0) and (1/2, 0, 1/2). In the same
direction, along the diagonal (1, 0, 1/2), the columns of
associates are formed due to the π−π-stacking interac-
tion of the PD (parallel-displaced) type [23] between
Thus, the results obtained indicate that the investigated
2-[bis(2-phenylethyl)thiophosphorylhydroxymethyl]-
1-organilimidazoles L1–L4 exhibit the ambidentate nature
and can form with Zn, Cd, Cu, Co, and Pd dichlorides both
the molecular complexes with the coordination center at
the heterocyclic N atom and the chelate complexes with
the coordination N
M
S bonds.
ACKNOWLEDGMENTS
The work was supported by the Siberian Division of
the plane-parallel aromatic cycles of benzimidazole the Russian Academy of Sciences (project no. 32).
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 7 2008

SYNTHESIS OF METAL COMPLEXES
491
x
0
z
y
Fig. 4. The structural unit packing in crystal I (projection on the plane xz).
Fig. 5. The overlap of plane-parallel benzimidazole fragments at the inversion center (0, 0, 0) in structure I.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 7 2008

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BAIKALOVA et al.
13. Ito, Sh., Liang, H., and Yoshifuji. M, J. Organomet.
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