A complex of gold(I) benzenethiolate with isocyanide: Synthesis and crystal and molecular structures

Article abstract of DOI:10.1007/s11172-010-0143-y

2,6-Dimethylphenyl isocyanide forms complexes with gold(I) chloride (complex 4) and gold(I) benzenethiolate (complex 5) but forms no stable complexes with gold alkanethiolates. A reaction of complex 5 with tetramethylthiuram disulfide yields gold(I) dimethyldithiocarbamate. Stable gold(III) derivatives cannot be obtained in such a way. Shortened intermolecular Au...Au contacts in complexes 4 and 5 (X-ray diffraction) suggest the presence of "aurophilic" interactions in them.

Full text of DOI:10.1007/s11172-010-0143-y

Russian Chemical Bulletin, International Edition, Vol. 59, No. 3, pp. 539—543, March, 2010
539
A complex of gold(I) benzenethiolate with isocyanide:
synthesis and crystal and molecular structures
V. P. Dyadchenko, N. M. Belov, M. A. Dyadchenko, Yu. L. Slovokhotov, A. M. Banaru, and D. A. Lemenovskii
Department of Chemistry, M. V. Lomonosov Moscow State University,
1 Leninskie Gory, 119992 Moscow, Russian Federation.
Fax: +7 (495) 932 8846. Eꢀmail: dyadchenko@org.chem.msu.ru
2,6ꢀDimethylphenyl isocyanide forms complexes with gold(I) chloride (complex 4) and
gold(I) benzenethiolate (complex 5) but forms no stable complexes with gold alkanethiolates.
A reaction of complex 5 with tetramethylthiuram disulfide yields gold(I) dimethyldithiocarꢀ
bamate. Stable gold(III) derivatives cannot be obtained in such a way. Shortened intermolecular
Au...Au contacts in complexes 4 and 5 (Xꢀray diffraction) suggest the presence of "aurophilic"
interactions in them.
Key words: 2,6ꢀdimethylphenyl isocyanide, complex of gold benzenethiolate with isocyaꢀ
nide, complex of gold chloride with isocyanide, gold benzenethiolate, gold decanethiolate,
gold 2ꢀmethylpropaneꢀ2ꢀthiolate, gold dimethyldithiocarbamate, "aurophilic" interactions.
Among isonitrile complexes of gold(I), thiolate comꢀ
plexes of the type X—Au•CN—R´ (X = RS (1)) still reꢀ
main poorly studied. Structural data for these complexes
are scarce in the literature. At the same time, isocyanide
complexes of gold thiolates are promising for the preparaꢀ
tion of calamitic (containing rodlike fragments in moleꢀ
cules) liquid crystals, by analogy with isocyanide comꢀ
plexes of polyfluorophenyl derivatives of gold.1
Some complexes of substituted gold benzenethiolates
with isocyanides are known to be stable2,3 and so are simꢀ
ilar complexes of pyridineꢀ2ꢀthiol and quinolineꢀ2ꢀthiol
and binuclear complexes of 1,3,4ꢀthiadiazoleꢀ2,5ꢀdithiol.3
However, complexes of unsubstituted gold benzenethiolate
with alkyl isocyanides of the type PhSAu•CN—CnH2n+1
are unstable. These complexes tend to decompose easily,
giving polymeric gold benzenethiolate through the loss of
the isocyanide ligand.4 At the same time, gold(I) chloride
is known to form the complexes RNCAuCl with both aryl
and alkyl isocyanides.5—7
here we compared the tendencies of various acido ligands
to form isocyanide complexes with gold.
Results and Discussion
Earlier,8 a complex of gold chloride has been obtained
from isocyanide 2 and the arsine complex Ph3AsAuCl.
We found that the metathesis reaction of isocyanide 2
with a tetrahydrothiophene complex of gold(I) chloride
(3) is a more convenient route to gold chloride complex 4
(Scheme 1).
Scheme 1
These data suggest that the stability of complexes of
the type 1 depends, at least, on two factors: the electroneꢀ
gativity of the acido ligand (X) and the πꢀwithdrawing
properties of the isocyanide ligand.
We studied reactions of gold thiolates with 2,6ꢀdiꢀ
methylphenyl isocyanide* (2). It turned out that this ligand
forms a complex with gold benzenethiolate but its comꢀ
plexes with gold alkanethiolates are unstable. At the same
time, it yields complexes of the formula RNCAuCl. Thus,
It should be noted that the reverse transformation 4→3
did not take place even in the presence of a twofold molar
excess of tetrahydrothiophene.
* The presence of two methyl groups in the ligand should make
the complexes more soluble.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 527—531, March, 2010.
1066ꢀ5285/10/5903ꢀ0539 © 2010 Springer Science+Business Media, Inc.

540
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 3, March, 2010
Dyadchenko et al.
Chloride complex 4 reacts with lithium benzenethiꢀ
It is known that the acidity of benzenethiol is 4—5 orders
of magnitude higher than the acidity of alkanethiols.9
Another factor that can be crucial for the above differꢀ
ence is the low solubilities of thiolates 7 and 8 in THF
under the conditions of the synthesis. This assumption is
confirmed by Xꢀray powder diffraction data for the gold
thiolates under discussion. Indeed, the diffraction patꢀ
terns of gold alkanethiolates 7 and 8 both prior to and after
the treatment with a solution of ligand 2 show intense
(though broadened) reflections from the crystalline phasꢀ
es. At the same time, freshly prepared gold benzenethiolate
6 is virtually Xꢀray amorphous. In addition, the gold atꢀ
oms in compounds 7 and 8 are shielded by bulky alkyl
ligands, which makes gold less accessible for isonitrile
molecules.
olate to give isonitrile complex 5 (Scheme 2). This is
a colorless crystalline solid (m.p. 117—119 °C, without
decomp.) soluble in organic solvents.
Scheme 2
It should be taken into account that the bond between
ligand 2 and the AuI atom in complex 5 is sufficiently
labile. For instance, complex 5 undergoes partial dissociꢀ
ation in THF, forming a small amount of insoluble benꢀ
zenethiolate 6. However, the precipitate dissolves upon
addition of an excess of isocyanide 2. It becomes clear
therefrom why isocyanide 2, which forms a complex with
Xꢀray amorphous benzenethiolate 6, cannot break the
crystal structures of alkanethiolates 7 and 8 and cannot
form complexes with these gold derivatives.
We studied a reaction of complex 5 with tetramethylꢀ
thiuram disulfide (9). Earlier,10 we have found that tetraꢀ
alkylthiuram disulfides add to organic derivatives
of gold(I), yielding gold(III) dimethyldithiocarbamates.
Complex 5 also reacts with compound 9 to give an
intensely colored red solution characteristic of gold(III)
derivatives. However, we failed to isolate gold(III) deꢀ
rivatives in the individual state under these conditions.
When stored, the solution gradually produces a bright
yellow precipitate of gold(I) dimethyldithiocarbamate (10)
(Scheme 4).
Alternatively, isonitrile complex 5 can be obtained by
the action of a solution of ligand 2 in THF on polymeric
gold benzenethiolate 6. The reaction is accompanied by
dissolution of compound 6 and the yield of complex 5 is
high (Scheme 3). This method of the synthesis of complex
5 is more convenient than the aforementioned one.
Scheme 3
Scheme 4
The stability of complex 5, in contrast to unstable comꢀ
plexes of gold benzenethiolate with alkyl isocyanides (see
above), is probably due to the stronger πꢀwithdrawing propꢀ
erties of ligand 2 compared to alkyl isocyanides, which
stabilizes the bond of this ligand with a postꢀtransition
metal, which is gold.
Our attempted synthesis of complexes of ligand 2 with
gold alkanethiolates (C10H21SAu)x (7) and (ButSAu)x (8),
which are analogs of compound 6, was unsuccessful. Polyꢀ
meric gold thiolate 7 or 8 remained inert in these reacꢀ
tions, regardless of the synthetic pathway. As mentioned
above, the difference between compound 6 and compounds
7 and 8 can be associated with the weaker acid character
of the ligands C10H21S– and ButS– compared to PhS–.
We determined the crystal and molecular structure of
complex 5 and, for comparison, the structure of gold chloꢀ
ride complex with isonitrile 4.

Gold benzenethiolate complex with isocyanide
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 3, March, 2010
541
Xꢀray diffraction study of complexes 4 and 5 clearly
...
revealed shortened intermolecular Au Au contacts giving
rise to dimers (Table 1; Figs 1, 2). Both structures contain
two crystallographically independent molecules; dimers
consists of nonidentical molecules. Previous Xꢀray difꢀ
fraction data for complex 4 were ambiguous in whether its
structure is built from discrete dimers11 or forms a united
polynuclear complex.9
N
N
C
C
...
Shortened intermolecular Au Au contacts, which are
Au(2)
intermediate between nonbonding metal—metal distancꢀ
es (>4 Å) and the shortest interatomic spacing in metallic
gold (2.884 Å), are characteristic of gold(I) complexes.
Such contacts are attributed to additional "aurophilic" inꢀ
teractions. The shortest contacts have been found in gold
complexes with tertiary phosphines (2.50—3.24 Å).12 In
complexes 4 and 5 with the isocyanide ligand, the distance
between adjacent Au atoms is longer (see Table 1); thereꢀ
Cl(2)
Cl(1)
Fig. 1. Dimers in the crystal structure 4. The Au(1)—Au(2) disꢀ
tance is 3.54 Å.
...
fore, the corresponding Au Au interactions are weaker.
Nevertheless, the dimer of benzenethiol complex 5
shows short nonbonding contacts between the S atom of
benzenethiolate and the C atom of the isocyanide ligand
(3.69 Å). The coordination of the isocyanide C atom is
nonlinear (see Table 1).
Au(2)
N
S(1)
S(1)
At the same time, in chloride complex 4 with the
crossed coordination "dumbbells" C—Au—Cl, the coordiꢀ
nation of the isocyanide C atom is nearly linear. The Au
atoms in the dimer approach each other (3.54 Å).
N
Au(1)
Crystal structure 5 is similar to that of the pyridineꢀ2ꢀ
thiol complex Au(2ꢀSPy)(2,6ꢀMe2C6H3NC) (see Ref. 3).
Although the space groups of these complexes are differꢀ
ent, their molecular structures and packing are very much
the same. In both complexes, the aromatic rings are virtuꢀ
ally coplanar. The angles between the meanꢀsquare planes
of the rings in structure 5 are about 6° or 7° for indepenꢀ
dent molecules; in Au(2ꢀSPy)(2,6ꢀMe2C6H3NC), these
angles are approximately 10°. Because of this, the moleꢀ
Fig. 2. Dimers in the crystal structure 5. The Au(1)—Au(2) disꢀ
tance is 3.64 Å.
cules in both crystals form dimers with parallel headꢀtoꢀ
tail arrangement of their planar fragments. The dimer in
Au(2ꢀSPy)(2,6ꢀMe2C6H3NC) is centrosymmetric, while
that in complex 5 is pseudocentrosymmetric. The meanꢀ
square deviation of the corresponding nonꢀhydrogen atꢀ
oms for the most closely spaced independent molecules
(the overlay procedure in the Mercury program13) is 0.19 Å.
Table 1. Selected structural characteristics of
complexes 4 and 5
...
Dimers are united into a chain with alternating Au Au
distances inside a dimer and between dimers. In the comꢀ
plex Au(2ꢀSPy)(2,6ꢀMe2C6H3NC), the alternating disꢀ
tances are 3.59 and 4.04 Å. In structure 5, these distances
are 3.65 and 3.88 Å. These values substantially exceed
twice the van der Waals radius of Au (1.66 Å according
to Bondi14). Otherwise, these structures should be regardꢀ
ed as topologically identical. For the closest possible
overlay of the first (Au(1)) molecule of structure 5 with
a Au(2ꢀSPy)(2,6ꢀMe2C6H3NC) molecule (meanꢀsquare
deviation is 0.15 Å), the corresponding deviation for
the molecule nearest to the second (Au(2)) molecule is
only 0.91 Å.
Parameter
Bond
4
5
d/Å
Au—C
Au—S
1.88, 1.96
—
1.91, 2.01
2.26, 2.27
Angle
ω/deg
C—Au—X
177, 178
(X = Cl)
169, 176
(X = S)
177, 177
166, 171
N—C—Au
Distance
e*/Å
To sum up, we developed convenient methods for the
synthesis of complexes of gold(I) chloride and gold(I) benꢀ
zenethiolate with 2,6ꢀdimethylphenyl isocyanide. We
demonstrated that gold alkanethiolates do not form stable
...
NC
...
S
—
3.54
3.69
3.65
Au Au
* e is the shortest distance.

542
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 3, March, 2010
Dyadchenko et al.
gold. Complex 4 was precipitated with light petroleum (20 mL).
The yield was 0.250 g (70%), colorless crystals, m.p. 142—144 °C.
Found (%): C, 29.55; H, 2.35; N, 3.72. C9H9AuClN. Calculatꢀ
ed (%): C, 29.73; H, 2.50; N, 3.85. H NMR (CDCl3), δ: 2.43
(s, 6 H, 2 CH3); 7.18 (m, 2 H, C6H3); 7.34 (m, 1 H, C6H3).
IR (Nujol): 2228 cm–1 (νNC).
complexes with isocyanide. A reaction of an isocyanide
complex of gold benzenethiolate with tetramethylthiuram
disulfide yields unstable gold(III) complexes. Xꢀray
diffraction for the gold complexes obtained reveals the
presence of nonbonding intermolecular Au Au contacts
(3.5—4.0 Å).
1
...
Complex of gold benzenethiolate with 2,6ꢀdimethylphenyl isoꢀ
cyanide (5). A. Synthesis from a gold chloride complex with tetraꢀ
hydrothiophene. A Schlenk apparatus filled with argon was
charged with a solution of benzenethiol (0.086 g, 0.78 mmol) in
THF (8 mL) and cooled to –40 °C. A 1.93 M solution of
nꢀbutyllithium (0.4 mL, 0.78 mmol) in hexane was added. The
reaction mixture was stirred for 10 min. At –30 °C, complex 3
(0.250 g, 0.78 mmol) and, after 5 min, a solution of 2,6ꢀdimethꢀ
ylphenyl isocyanide (2) (0.100 g, 0.78 mmol) in THF (20 mL)
were added. The resulting mixture was stirred for 30 min without
forced cooling. The precipitate that formed was filtered off and
the filtrate was concentrated in vacuo. The residue was dissolved
in a minimum amount of benzene and complex 5 was precipitatꢀ
ed with an excess of light petroleum. The yield of complex 5 was
0.130 g (38%), m.p. 117—119 °C.
B. Synthesis from gold benzenethiolate. A solution of 2,6ꢀdiꢀ
methylphenyl isocyanide (2) (0.30 g, 2.29 mmol) in THF (10 mL)
was added to a suspension of gold benzenethiolate (6) (0.50 g,
1.63 mmol) in THF (20 mL). The reaction mixture was stirred
for 25 min and concentrated in vacuo to a volume of 10 mL. The
resulting light yellow solution was carefully diluted with light
petroleum (4 mL) and kept in a refrigerator for 3 h. Then light
petroleum (4 mL) was added again and the solution was kept in
a refrigerator for 16 h. Then another portion of light petroleum
(4 mL) was added. After several hours, the precipitate that formed
was filtered off, washed with light petroleum, and dried in air.
The yield of complex 5 was 0.67 g (94%), yellowish crystals,
m.p. 117—119 °C. Found (%): C, 41.42; H, 3.37; N, 3.22.
C15H14NSAu. Calculated (%): C, 41.20; H, 3.23; N, 3.20.
1H NMR (CDCl3), δ: 2.45 (s, 6 H, 2 CH3); 7.01 (1 H); 7.09—7.17
(m, 4 H, C6H4ꢀS); 7.56—7.58 (2 H); 7.33 (m, 1 H). IR (Nujol):
2228 cm–1 (νNC).
Gold decanethiolate (7). Methanol (30 mL) and decanethiol
(1.76 g, 10.1 mmol) were added to a stirred solution of
HAuCl4•3H2O (1.00 g, 2.54 mmol) in water (5 mL). The reacꢀ
tion mixture was stirred for 10 min. The yellowish precipitate of
gold decanethiolate that formed was filtered off, washed with
acetone (10 mL) and diethyl ether (10 mL), and dried on the
filter. The yield of compound 7 was 0.63 g (67%), yellowish
powder (decomp. > 120 °C). Found (%): C, 32.23; H, 5.70.
C10H21ClSAu. Calculated (%): C, 32.43; H, 5.72.
Gold 2ꢀmethylpropaneꢀ2ꢀthiolate (8). Methanol (30 mL) and
2ꢀmethylpropaneꢀ2ꢀthiol (0.92 g, 10.16 mmol) were added to
a stirred solution of HAuCl4•3H2O (1.00 g, 2.54 mmol) in water
(5 mL). The reaction mixture was stirred for 1 h. The pinkish
precipitate of gold 2ꢀmethylpropaneꢀ2ꢀthiolate that formed was
filtered off, washed with acetone (10 mL) and diethyl ether
(10 mL), and dried on the filter. The yield of compound 8 was
0.67 g (92%), pinkish powder (decomp. > 216 °C). Found (%):
C, 16.92; H, 3.13. C4H9SAu. Calculated (%): C, 16.79; H, 3.17.
Reaction of gold decanethiolate (7) with isocyanide 2. A soluꢀ
tion of isocyanide (2) (0.262 g, 2 mmol) was added to a suspenꢀ
sion of decanethiolate 7 (0.740 g, 2 mmol) in THF (10 mL). The
mixture was stirred for 30 min. The precipitate that formed was
filtered off, thoroughly washed with THF (in two portions of
Experimental
2,6ꢀDimethylformanilide. A mixture of 2,6ꢀdimethylaniline
(10.00 g, 0.083 mol) and 93% formic acid (9.30 g, 0.188 mol) was
refluxed in toluene (30 mL) with a Dean—Stark trap until water
ceased to evolve (2.5 h). Then the solvent was removed in vacuo
and the residue was recrystallized from aqueous ethanol. The
yield of 2,6ꢀdimethylformanilide was 6.8 g (60%), colorless crysꢀ
tals, m.p. 163—164 °C (cf. Ref. 15: m.p. 164—165 °C).
2,6ꢀDimethylphenyl isocyanide (2). A solution of diphosgene
(0.5 mL) in CH2Cl2 (4 mL) was added dropwise to a boiling
suspension of 2,6ꢀdimethylformanilide (1.00 g, 6.7 mmol) in
a mixture of anhydrous triethylamine (4.7 mL) and CH2Cl2
(17 mL). The reaction mixture was refluxed with stirring for
15 min and then washed with 10% aqueous Na2CO3. The organꢀ
ic layer was separated, dried with anhydrous Na2SO4, and conꢀ
centrated in vacuo. The residue was chromatographed on silica
gel with chloroform—light petroleum (1 : 1) as the eluent. The
yield of isocyanide 2 was 0.75 g (85%), colorless powder,
m.p. 72.5—74 °C (cf. Ref. 16: m.p. 74—75 °C). 1H NMR
(CDCl3), δ: 2.41 (s, 6 H, 2 CH3); 7.15 (m, 3 H, C6H4). IR
(Nujol): 2130 cm–1 (νNC).
Complex of gold(I) chloride with tetrahydrothiophene (3). The
synthesis was carried out in a shaded room. A solution of bis(2ꢀ
hydroxyethyl) sulfide (1.2 mL, 11.6 mmol) in ethanol (7 mL)
was added at 0 °C to a stirred solution of HAuCl4•3H2O (2.20 g,
2.8 mmol) in water (10 mL). The reaction mixture was stirred for
10 min. Then a solution of tetrahydrothiophene (0.56 mL, 0.28 g,
6.4 mmol) in ethanol (6 mL) was added and stirring was continꢀ
ued for an additional 10 min. The precipitate of complex 3 that
formed was filtered off, washed with water (2×10 mL) to a neuꢀ
tral reaction and then successively with ethanol (10 mL), aceꢀ
tone (10 mL), and diethyl ether (10 mL), and dried in air. The
yield of complex 3 was 1.50 g (84%), beige powder (decomp. >
> 140 °C). Found (%): C, 14.98; H, 2.50; S, 9.19. C4H8ClSAu.
Calculated (%): C, 14.99; H, 2.52; S, 10.00.
Gold benzenethiolate (6). A solution of benzenethiol (2.26 g,
20.5 mmol) in methanol (8 mL) was added for 5 min to a stirred
solution of HAuCl4•3H2O (2.10 g, 5.33 mmol) in a mixture of
water (12 mL) and methanol (61 mL). The reaction mixture was
stirred for 10 min. The precipitate of gold benzenethiolate that
formed was filtered off, washed with methanol (60 mL), acetone
(60 mL), and diethyl ether (60 mL), and dried in air. The yield of
compound 6 was 1.60 g (98%), yellowish powder (decomp. >
>178 °C). Found (%): C, 23.71; H, 1.50. C6H5SAu. Calculatꢀ
ed (%): C, 23.54; H, 1.65.
Complex of gold chloride with 2,6ꢀdimethylphenyl isocyanide
(4). A solution of 2,6ꢀdimethylphenyl isocyanide (2) (0.131 g,
1 mmol) in THF (20 mL) was added to a stirred solution of
a complex of gold(I) chloride with tetrahydrothiophene (3)
(0.320 g, 1 mmol) in THF (30 mL). The reaction mixture was
stirred for 10 min and concentrated in vacuo to a volume of
~10 mL. The solution was filtered to remove traces of metallic

Gold benzenethiolate complex with isocyanide
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 3, March, 2010
543
3
5 and 10 mL), and dried in air to a constant weight. Decanethiꢀ
olate 7 (0.706 g, 95%) was recovered. Its Xꢀray diffraction patꢀ
tern was identical with that of the starting reagent. The filtrate
was combined with the rinsing portions of THF and concentratꢀ
ed in vacuo. The residue was dissolved in diethyl ether; the reꢀ
sulting slightly turbid solution was filtered and concentrated
in vacuo. The residue was dried to a constant weight. Isocyanide
2 (0.25 g, 95%) was recovered, m.p. 72—74 °C.
β = 92.14(2)°, γ = 112.56(3)°, V = 710.2(4) Å , θ
= 29.96°.
max
The number of independent reflections is 4198; the number of
reflections with F > 4σ(F) is 3173, R1 = 0.0283.
We are grateful to V. N. Okulov for his assistance in
the experimental work, to F. M. Dolgushin for his assisꢀ
tance in the singleꢀcrystal Xꢀray diffraction experiment
with complexes 4 and 5, and to T. V. Filippova for collecꢀ
tion of Xꢀray powder diffraction data for compounds
6, 7, and 8.
This work was financially supported by the Rusꢀ
sian Foundation for Basic Research (Project No. 08ꢀ03ꢀ
00920ꢀa).
Reaction of gold 2ꢀmethylpropaneꢀ2ꢀthiolate (8) with isocyaꢀ
nide 2 was carried out as described above for decanethiolate 7.
The starting reagent 8 (93%) was recovered.
Reaction of complex 5 with tetramethylthiuram disulfide (9).
Isocyanide 2 (0.01 g, 0.08 mmol) and a solution of compound 9
(0.12 g, 0.5 mmol) were added to a solution of complex 5 (0.219 g,
0.5 mmol) in THF (5 mL). The reaction mixture was stirred for
2 h. The precipitate of gold dimethyldithiocarbamate (10) that
formed was filtered off and washed with THF. The filtrate
was concentrated in vacuo. The product from the residue was
extracted with THF and combined with the main crop of
compound 10. The yield of gold dimethyldithiocarbamate (10)
was 0.122 g (77%). Found (%): C, 11.70; H, 1.91; N, 4.45.
C15H14NSAu. Calculated (%): C, 11.36; H, 1.91; N, 4.42.
Xꢀray diffraction analysis. Xꢀray powder diffraction data for
polycrystalline samples were collected at room temperature in
the Bragg—Brentano geometries on a Rigaku DMAX 2500 difꢀ
fractometer (Science Materials Department of the Moscow State
University) equipped with a vertical goniometer and a rotating
copper anode Xꢀray tube (generator operating at 50 kV, 250 mA,
λ =1.5418 Å (CuꢀKα), diffracted beam monochromator, scintilꢀ
lation point detector, continuous scan with a step of 0.02°,
4° < 2θ < 64°, scan rate 5 deg min–1).
Single crystals of the complexes were obtained by slow preꢀ
cipitation with light petroleum from their solutions in THF. Xꢀray
diffraction study of complexes 4 and 5 was carried out at the
Crystallographic Center of the A. N. Nesmeyanov Institute of
Organoelement Compounds (Russian Academy of Sciences) on
an EnrafꢀNonius CAD 4 diffractometer (graphite monochromaꢀ
tor, λ(MoꢀKα) = 0.71073 Å, θ/2θ scan mode) at room temperaꢀ
ture. The structures were solved by the direct methods with the
SHELXTL program package.17 The hydrogen atoms were locatꢀ
ed from difference electronꢀdensity maps. The structures were
refined anisotropically (isotropically for H atoms) on F 2 by the
fullꢀmatrix leastꢀsquares method. The structural parameters of
complexes 4 and 5 have been deposited with the Cambridge
Crystallographic Data Center (CCDC Nos. 739 392 and 739 391,
respectively).
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14. A. Bondi, J. Phys. Chem., 1964, 68, 441.
15. W. R. Hodgkinson, L. Limpach, J. Chem. Soc., 1900, 65.
16. M. G. B. Drew, G. H. Dodd, J. M. Williamson, G. R. Wilꢀ
ley, J. Organomet. Chem., 1986, 314, 63.
17. G. M. Sheldrick, SHELXTL, 1998, Ver. 5.10, Structure Deꢀ
termination Software Suite, Bruker AXS, Madison, Wisconꢀ
sin, USA.
Complex 4. Monoclinic crystals, space group P21/n, Z = 8,
a = 10.651(2) Å, b = 17.289(4) Å, c = 11.860(2) Å, β = 97.51(3)°,
3
V = 2165.1(8) Å , θ
= 27.96°. The number of independent
max
reflections is 5078; the number of reflections with F > 4σ(F) is
2658, R1 = 0.0419.
Complex 5. Triclinic crystals, space group P1, Z = 2,
a = 7.381(3) Å, b = 8.274(3) Å, c = 12.889(3) Å, α = 100.35(2)°,
Received September 14, 2009;
in revised form November 30, 2009