Gold(I) Complexes with the nido-Diphosphino Ligand [7,8-(Ph2P)2-7,8-C2B9H10 ]-. Preparation of the First Metallocarborane Complex of this Ligand

Article abstract of DOI:10.1021/ic951204x

The reaction of [AuCl(PR₃)] with [1,2-(Ph₂P)₂-1,2-C₂B₁₀H ₁₀] in refluxing ethanol proceeds with partial degradation (removal of a boron atom adjacent to carbon) of the closo species to give [Au{(PPh₂)₂C₂B₉H ₁₀}(PR₃)] [PR₃ = PPh₃ (1), PPh₂Me (2), PPh₂(4-Me-C₆H₄) (3), P(4-Me-C₆H₄)₃ (4), P(4-OMe-C₆H₄)₃ (5)]. Similarly, the treatment of [Au₂Cl₂(μ-P-P)] with [1,2-(Ph₂P)₂-1,2-C₂B₁₀H ₁₀] under the same conditions leads to the complexes [Au₂- {(PPh₂)₂C₂B₉H₁₀} ₂(μ-P-P)] [P-P = dppe = 1,2-bis(diphenylphosphino)ethane (6), dppp = 1,3-bis(diphenylphosphino)propane (7)], where the dppe or dppp ligands bridge two gold nido-diphosphine units. The reaction of 1 with NaH leads to removal of one proton, and further reaction with [Au(PPh₃)(tht)]ClO₄ gives the novel metallocarborane compound [Au₂{(PPh₂)₂C₂B₉H ₉}(PPh₃)₂] (8). The structure of complexes 1 and 7 have been established by X-ray diffraction. [Au{(PPh₂)₂C₂B₉H ₁₀}(PPh₃)] (1) (dichloromethane solvate) crystallizes in the monoclinic space group P2₁/c, with a = 17.326(3) A?, b = 20.688(3) A?, c = 13.442(2) A?, β = 104.710(12)°, Z = 4, and T= -100 °C. [Au₂{(PPh₂)₂C₂B₉H ₁₀}₂(μ-dppp)] (7) (acetone solvate) is triclinic, space group P1?, a = 13.432(3) A?, b= 18.888(3) A?, c = 20.021(3) A?, α = 78.56(2)°, β = 72.02(2)°, γ = 73.31(2)°, Z = 2, and T =-100 °C. In both complexes the gold atom exhibits trigonal planar geometry with the 7,8-bis(diphenylphosphino)- 7,8-dicarba-nido-undecaborate(1-) acting as a chelating ligand.

Full text of DOI:10.1021/ic951204x

Inorg. Chem. 1996, 35, 1361-1366
1361
Gold(I) Complexes with the nido-Diphosphino Ligand [7,8-(Ph2P)2-7,8-C2B9H10]-.
Preparation of the First Metallocarborane Complex of this Ligand. Crystal Structures of
[Au{(PPh2)2C2B9H10}(PPh3)]‚CH2Cl2 and [Au2{(PPh2)2C2B9H10}2{(PPh2)2(CH2)3}]‚3Me2CO
Olga Crespo,† M. Concepcio´n Gimeno,† Peter G. Jones,‡ and Antonio Laguna*,†
Departamento de Qu´ımica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain, and Institut fu¨r Anorganische und Analytische
Chemie, Technische Universita¨t Braunschweig, Postfach 3329, 38023 Braunschweig, Germany
ReceiVed September 15, 1995X
The reaction of [AuCl(PR3)] with [1,2-(Ph2P)2-1,2-C2B10H10] in refluxing ethanol proceeds with partial degradation
(removal of a boron atom adjacent to carbon) of the closo species to give [Au{(PPh2)2C2B9H10}(PR3)] [PR3 )
PPh3 (1), PPh2Me (2), PPh2(4-Me-C6H4) (3), P(4-Me-C6H4)3 (4), P(4-OMe-C6H4)3 (5)]. Similarly, the treatment
of [Au2Cl2(µ-P-P)] with [1,2-(Ph2P)2-1,2-C2B10H10] under the same conditions leads to the complexes [Au2-
{(PPh2)2C2B9H10}2(µ-P-P)] [P-P ) dppe ) 1,2-bis(diphenylphosphino)ethane (6), dppp ) 1,3-bis(diphenylphos-
phino)propane (7)], where the dppe or dppp ligands bridge two gold nido-diphosphine units. The reaction of 1
with NaH leads to removal of one proton, and further reaction with [Au(PPh3)(tht)]ClO4 gives the novel
metallocarborane compound [Au2{(PPh2)2C2B9H9}(PPh3)2] (8). The structure of complexes 1 and 7 have been
established by X-ray diffraction. [Au{(PPh2)2C2B9H10}(PPh3)] (1) (dichloromethane solvate) crystallizes in the
monoclinic space group P21/c, with a ) 17.326(3) Å, b ) 20.688(3) Å, c ) 13.442(2) Å, â ) 104.710(12)°, Z
) 4, and T ) -100 °C. [Au2{(PPh2)2C2B9H10}2(µ-dppp)] (7) (acetone solvate) is triclinic, space group P1h, a )
13.432(3) Å, b ) 18.888(3) Å, c ) 20.021(3) Å, R ) 78.56(2)°, â ) 72.02(2)°, γ ) 73.31(2)°, Z ) 2, and T )
-100 °C. In both complexes the gold atom exhibits trigonal planar geometry with the 7,8-bis(diphenylphosphino)-
7,8-dicarba-nido-undecaborate(1-) acting as a chelating ligand.
Introduction
gold(I) complexes with the 1,2-bis(diphenylphosphino)-o-car-
borane ligand,10-12 and also of related species for silver(I).13
o-Carborane is an interesting backbone because its electron-
withdrawing power, large size, and extensive electron delocal-
ization confer an unusual stability on the molecule. These
factors, together with the great tendency of the 1,2-bis-
(diphenylphosphine)-o-carborane ligand to act as a chelating
ligand, have allowed us to prepare novel complexes with
o-carborane derivatives as ligands. However, very little work
has been done on the partially degraded anionic ligand [7,8-
(Ph2P)2-7,8-C2B9H10]-, and the only reported complexes are
[Cu{(PPh2)2C2B9H10}(PPh3)], (NMe4)[Cu{(PPh2)2C2B9H10}Cl-
(PPh3)], and [Cu{(PPh2)2C2B9H10}(PPh3)(Me2CO)].14 This
ligand has several coordination modes: first exo-nido-coor-
dination to the phosphorus atoms, and second η5-coordination,
after deprotonation, to the open pentagonal C2B3 face, thus
forming metallocarboranes. No examples combining both types
of coordination have been reported thus far.
1,2-Dicarba-closo-dodecaborane (o-carborane) forms a great
variety of derivatives as a consequence of the high resistance
of the o-carborane cage to chemical attack.1 Despite their cost,
such properties make them attractive for various specialized
applications. These include the incorporation of high concentra-
tions of boron atoms in tumor-seeking drugs for boron neutron
capture therapy (BNCT),2-4 the synthesis of high temperature
polymers,5 the production of ceramics related to boron carbide,6
or the synthesis of derivatives with nonlinear optical (NLO)
properties.7 Furthermore, the ability to form nido anionic
species by treatment with nucleophiles has led to their use in
coordination chemistry with potential applications as novel
catalysts,8 radiochemical drugs,9 etc.
During our studies using o-carborane derivatives as ligands,
we have reported the synthesis of unusual higher-coordinated
† Universidad de Zaragoza-CSIC.
‡ Technische Universita¨t Braunschweig.
Here we describe the synthesis of three-coordinate gold(I)
complexes with [7,8-(Ph2P)2-7,8-C2B9H10]- and the preparation
of the first metallocarborane complex of this ligand.
X Abstract published in AdVance ACS Abstracts, February 1, 1996.
(1) Grimes, R. N. Carboranes; Academic Press: New York, 1970.
(2) Barth, R. F.; Soloway, A. H. ; Fairchild, R. G. Cancer Res. 1990, 50,
1061.
(3) Hawthorne, M. F. Pure Appl. Chem. 1991, 63, 327.
(4) Shelly, K.; Feakes, D. A.; Hawthorne, M. F.; Schmidt, P. G.; Krisch,
T. A.; Bauer, W. F. Proc. Natl. Acad. Sci. U.S.A. 1992, 89, 9039.
(5) Brown, D. A.; Colquhoun, H. M.; Daniels, J. A.; MacBride, J. A. H.;
Stephenson, I. R.; Wade, K. J. Mater. Chem. 1992, 2, 793 and
references cited therein.
Results and Discussion
It has been reported that the treatment of 1,2-bis(diphen-
ylphosphino)-o-carborane with alkoxides does not produce the
expected nido species, leading instead to the 7,8-dicarba-nido-
(6) Sneddon, L. G.; Mirabelli, M. G.; Lynch, A. T.; Fazen, P. J.; Su, K.;
Beck, J. S. Pure Appl. Chem. 1991, 63, 407.
(7) Murphy, D. M.; Mingos, D. M. P.; Haggitt, J. L.; Powel, H. R.;
Westcott, S. A.; Marder, T. B.; Taylor, N. J.; Kanio, D. R. J. Mater.
Chem. 1993, 3, 139.
(10) Crespo, O.; Gimeno, M. C.; Laguna, A.; Jones, P. G. J. Chem. Soc.,
Dalton Trans. 1992, 1601.
(11) Crespo, O.; Gimeno, M. C.; Jones, P. G.; Laguna, A. J. Chem. Soc.,
Chem. Commun. 1993, 1696.
(8) Hawthorne, M. F., Liebman, J. F., Greenberg, A., Willians, R. E.,
Eds. AdVances in Boron and the Boranes; VCH Publishers: New
York, 1988; Chapter 10, p 225.
(9) Paxton, R. J.; Beatty, B. G.; Hawthorne, M. F.; Varadarajan, A.;
Willians, L. E.; Curtis, F. L.; Knobler, C. B.; Beatty, J. D.; Shively,
J. E. Proc. Natl Acad. Sci. U.S.A. 1991, 88, 3387.
(12) Crespo, O.; Gimeno, M. C.; Jones, P. G.; Laguna, A. Inorg. Chem.
1994, 33, 6128.
(13) Bembenek, E.; Crespo, O.; Gimeno, M. C.; Jones, P. G.; Laguna, A.
Chem. Ber. 1994, 127, 835.
(14) Teixidor, F. Vin˜as, C.; Abad, M. M.; Lopez, M.; Casabo´, J.
Organometallics 1993, 12, 3766.
0020-1669/96/1335-1361$12.00/0 © 1996 American Chemical Society

1362 Inorganic Chemistry, Vol. 35, No. 5, 1996
Crespo et al.
Scheme 1a
a Key: (i) EtOH/∆; (ii) [Au2Cl2(µ-P-P)], EtOH/∆; (iii) [AuCl(PR3)], EtOH/∆; (iv) NaH, [Au(PPh3)(tht)]ClO4; (v) [AuCl(PR3)], CH2Cl2.
undecaborate(1-) anion by C-P cleavage, and also that the
diphosphine is stable in refluxing ethanol.14 However com-
plexation to a metal centre makes the partial degradation of the
carborane moiety easier.14 We have prepared gold(I) complexes
with the ligand [(Ph2P)2C2B9H10]- using this method. Thus the
reaction of [AuCl(PPh3)] with [(Ph2P)2C2B10H10] in refluxing
ethanol proceeds with removal of one of the boron atoms
adjacent to carbon and gives the neutral complexes [Au-
{(PPh2)2C2B9H10}(PR3)] [PR3 ) PPh3 (1), PPh2Me (2), PPh2-
(4-Me-C6H4) (3), P(4-Me-C6H4)3 (4), P(4-OMe-C6H4)3 (5)].
The first step in these processes must be the coordination of
the gold atom to the diphosphine, followed by the partial
degradation of the carborane moiety. To prove this we have
carried out the reaction with [Au{(PPh2)2C2B10H10}(PR3)]-
ClO4,10 which contains the closo diphosphine, in refluxing
ethanol, also obtaining the neutral nido species (see Scheme
1).
In the IR spectra of these complexes the absorptions arising
from the B-H stretching modes of the o-carborane nucleus
appear at lower energy than the complexes that contain the closo
carboranes.10 Teixidor et al. have observed15 that the position
of the B-H bands in the IR spectrum is highly significant when
studying 1,2-dicarba-closo-dodecaborane or 7,8-dicarba-nido-
undecaborate derivatives; with few exceptions it seems that if
υ(B-H) is < 2550 cm-1, the cluster is partially degraded, but
if υ(B-H) is > 2550 cm-1, the cluster is a closo compound.
This is consistent with the values found in our complexes.
Their 31P{1H} NMR spectra show AB2 systems, except for
PR3 ) PPh2Me which presents an AX2 system. The AB2
systems show eight transitions and simulated spectra agree with
experimental findings. Chemical shifts and coupling constants
are very similar to those found in the spectra of the analogous
Figure 1. Molecular structure of 1 with the atom-numbering scheme.
Phenyl hydrogen atoms are omitted for clarity; radii are arbitrary.
four signals appear, one of which has a shoulder. The range of
the resonances is from ca. -5 to -38 ppm; the high-field signals
are assigned to the boron atoms with higher coordination
number.
The positive-ion fast atom bombardment (FAB) mass spectra
of these derivatives show the molecular peak [M]+ at m/z )
961 (1, 69%), 899 (2, 100%), 975 (3, 100%), 1003 (4, 100%)
and 1051 (5, 47%). Other characterization data for 1-8 are
given in Table 1.
The crystal structure of complex 1 has been determined by
X-ray diffraction, and is shown in Figure 1. Atom coordinates
are given in Table 2 and selected bond lengths and angles in
Table 3. The gold atom displays trigonal planar coordination
by the three phosphorus atoms, and is only 0.076(1) Å out of
the phosphorus plane. The major deviation from ideal geometry
1
closo derivatives. In the H NMR spectra a multiplet around
-2 ppm appears; this corresponds to the proton of the eliminated
boron atom, which possesses a marked mobility in solution.
The 11B NMR spectra show the characteristic pattern of the 7,8-
dicarba-nido-undecaborate(1-) derivatives, which usually present
five resonances in a ratio 2:3:2:1:1.16-18 In our complexes only
(16) Howe, D. V.; Jones, C. J.; Wiersema, R. J.; Hawthorne, M. F. Inorg.
Chem. 1971, 10, 2516.
(15) Teixidor, F.; Rius, J.; Miravitlles, C.; Vin˜as, C.; Escriche, L.; Sanchez,
(17) Teixidor, F.; Vin˜as, C.; Rudolph, R. W. Inorg. Chem. 1986, 25, 3339.
(18) Reed, D. Chem. Soc. ReV. 1993, 109.
E.; Casabo´, J. Inorg. Chim. Acta 1990, 176, 61.

Gold(I) Metallocarboranes
Inorganic Chemistry, Vol. 35, No. 5, 1996 1363
Table 1. Analytical, Conductivity, and NMR Data and ν(B-H) Frequencies for Complexes 1-8
anal. (%)a
31P{1H}c
1Hc
yield
(%)
ν(B-H)/
b
complex
C
H
ΛM
δ
J(PP)
δ
J(PP)
cm-1
[Au{(PPh2)2C2B9H10}(PPh3)] (1)
76
71
74
71
68
81
94
75
54.55
(55.0)
51.95
(52.1)
55.2
(55.45)
56.15
(56.25)
53.5
(53.7)
52.1
(52.2)
52.35
(52.45)
52.6
4.50
(4.7)
4.75
(4.8)
4.6
(4.85)
5.05
(5.1)
4.75
(4.9)
4.35
(4.7)
4.8
1
45.8
63.1
26.2 (t)
63.4 (d)
44.8
62.8
43.2
62.6
41.3
130.6
2536
2521
2524
2521
2587
2529
2531
2526
[Au{(PPh2)2C2B9H10}(PPh2Me)] (2)
0
0
0
1
1
2
4
134.8
132.1
132.4
133.0
131.23
131.35
128.7
2.21(d)
2.42 (s)
2.43 (s)
3.8 (s)
8.79
[Au{(PPh2)2C2B9H10}{PPh2(4-Me-C6H4)}] (3)
[Au{(PPh2)2C2B9H10}{P(4-Me-C6H4)3}] (4)
[Au{(PPh2)2C2B9H10}{P(4-OMe-C6H4)3}] (5)
[Au2{(PPh2)2C2B9H10}2(µ-dppe)] (6)
[Au2{(PPh2)2C2B9H10}2(µ-dppp)] (7)
[Au2{(PPh2)2C2B9H9}(PPh3)2] (8)
62.4
63.7 (d)
42.8 (t)
63.4 (d)
38.0 (t)
46.6 (t)
66.0 (d)
41.0 (m)
2.4 (m)
2.1 (m)
4.8 (m)
(4.8)
4.2
(4.25)
(52.45)
a Calculated values in parentheses. b In acetone, Ω-1 cm2 mol-1
d ) doublet, s ) singlet, and m ) multiplet.
.
c Recorded in CDCl3, values in ppm, coupling constants in Hz, with t ) triplet,
Table 2. Atomic Coordinates [×104] and Equivalent Isotropic Displacement Parameters [Å2 × 103] for compound 1a
x
y
z
U(eq)
x
y
z
U(eq)
Au
P(1)
P(2)
P(3)
C(1)
C(2)
B(1)
B(2)
B(3)
B(4)
B(5)
B(6)
B(7)
B(8)
B(9)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(31)
C(32)
C(33)
7305.6(1)
6595.9(7)
6552.1(7)
8323.0(7)
5655(3)
5625(3)
5001(3)
4513(4)
5051(3)
5214(3)
4734(3)
4058(3)
4076(3)
4781(3)
4187(3)
6370(3)
6475(4)
6314(4)
6064(4)
5965(3)
6112(3)
7125(3)
7774(3)
8201(4)
7997(4)
7371(3)
6934(3)
7121(3)
7896(3)
8372(3)
4974.7(1)
4185.2(6)
5745.9(6)
5014.7(6)
4565(2)
5339(2)
5636(3)
4948(3)
4265(3)
4933(3)
5619(3)
5367(3)
4488(3)
4242(3)
4911(3)
3406(2)
3320(3)
2719(3)
2214(3)
2301(3)
2888(2)
3975(2)
3563(3)
3396(3)
3640(3)
4063(3)
4231(3)
5952(2)
6169(3)
6365(3)
6814.5(1)
7531.4(10)
7508.1(10)
6019.6(10)
7586(4)
7566(4)
8161(5)
8607(5)
8219(4)
6437(4)
6780(4)
7472(4)
7497(4)
6842(4)
6368(4)
6918(4)
5938(5)
5467(6)
5964(6)
6936(6)
7405(4)
8837(4)
8979(5)
9958(5)
10801(5)
10679(4)
9697(4)
8802(4)
8889(4)
9818(5)
23.2(1)
20.6(3)
20.4(3)
24.3(3)
19.3(10)
20.3(10)
23.9(12)
27.5(12)
22.7(12)
23.6(12)
24.7(12)
23.7(12)
26.4(13)
24.6(13)
24.8(12)
25.3(11)
43.9(14)
64(2)
56(2)
48(2)
36.1(13)
24.9(11)
48(2)
59(2)
50(2)
41.7(14)
31.8(12)
22.1(10)
39.0(14)
47(2)
C(34)
C(35)
C(36)
C(41)
C(42)
C(43)
C(44)
C(45)
C(46)
C(51)
C(52)
C(53)
C(54)
C(55)
C(56)
C(61)
C(62)
C(63)
C(64)
C(65)
C(66)
C(71)
C(72)
C(73)
C(74)
C(75)
C(76)
C(99)
Cl(1)
Cl(2)
8093(4)
7335(4)
6851(3)
6267(3)
6089(3)
5874(3)
5846(3)
6021(4)
6228(3)
8307(3)
8651(3)
8616(4)
8233(4)
7885(4)
7920(3)
9268(3)
9947(3)
10665(3)
10715(4)
10048(4)
9326(3)
8439(3)
7820(3)
7860(3)
8515(3)
9133(4)
9096(3)
10262(7)
10418(2)
9867.7(14)
6345(3)
6116(3)
5928(2)
6524(2)
6567(2)
7149(3)
7698(2)
7661(2)
7078(2)
5700(2)
5686(3)
6216(3)
6772(3)
6794(3)
6262(3)
5059(2)
5335(3)
5325(3)
5036(3)
4763(3)
4775(3)
4319(2)
4162(3)
3620(3)
3220(3)
3371(3)
3914(3)
2141(4)
1943(2)
2915.4(11)
10689(5)
10620(4)
9690(4)
6908(4)
5836(4)
5362(5)
5931(5)
6991(5)
7482(4)
5169(4)
4341(4)
3719(5)
3904(5)
4703(6)
5336(5)
6977(4)
6789(4)
7530(5)
8466(5)
8676(5)
7934(4)
5239(4)
4391(4)
3816(4)
4072(5)
4905(5)
5483(4)
8040(8)
6899(3)
8103(2)
45.9(15)
42.5(14)
29.5(12)
23.8(11)
29.8(12)
38.5(13)
39.7(14)
42.6(15)
31.8(12)
30.4(12)
40.4(14)
56(2)
60(2)
55(2)
43.7(15)
30.4(11)
34.3(12)
42.2(14)
50(2)
51(2)
41.7(14)
28.3(11)
40.5(14)
41.2(14)
43.2(14)
49(2)
37.2(13)
114(3)
132.8(11)
89.7(7)
a U(eq) is defined as one-third of the trace of the orthogonalized Uij tensor.
is associated with the bite angle of the diphosphine, P(1)-Au-
P(2) 84.91(4)°. This angle is even narrower than that in the
closo species [Au{(PPh2)2C2B10H10}(PPh3)]ClO4 [90.2(1)°].10
The bond to the monodentate phosphine, 2.2831(13) Å, is
appreciably shorter than those to the diphosphine [2.3896(13)
and 2.3952(12) Å]; a similar pattern was observed in [Au-
{(PPh2)2C2B10H10}(PPh3)]ClO4 [2.318, 2.405, 2.417(1) Å].
Broadly similar values were found for other three coordinate
complexes such as [Au(PPh3)3]+ (three independent investi-
gations)19-21 [2.345-2.408 Å], or [Au(dppf)(PPh3)]ClO4 [2.343-
(2)-2.409(2) Å].22 The P-C bond lengths are 1.827(5) and
1.832(5) Å, somewhat shorter than those in the closo species,
1.883(5) and 1.870(5) Å, possibly because of the negative charge
of the carborane moiety. The chelate ring displays an envelope
conformation, with the gold atom 0.85 Å out of the plane of
the other four atoms. The central boron atom of the C2B3 open
face is bonded to two hydrogen atoms, with B-H 1.08(3) and
1.09(3) Å.
The reaction of [Au2Cl2(µ-P-P)] with 2 equiv of [(Ph2P)2-
C2B10H10], under the same conditions of refluxing ethanol,
proceeds in a similar manner, and the complexes [Au2-
{(PPh2)2C2B9H10}2(µ-P-P)] [P-P ) 1,2-bis(diphenylphosphino)-
ethane, dppe (6), 1,3-bis(diphenylphosphino)propane, dppp (7)]
are isolated. Complexes 6 and 7 are yellow solids stable to air
and moisture and behave as non-conductors in acetone solution.
(19) Jones, P. G. J. Chem. Soc., Chem. Commun. 1980, 1031.
(20) Guggenberger, L. J. J. Organomet. Chem. 1984, 81, 271.
(21) Jones, P. G. Acta Crystallogr., Sect. B 1980, 36, 3105.
(22) Gimeno, M. C.; Jones, P. G.; Laguna, A.; Sarroca, C. Inorg. Chem.
1993, 32, 5927.

1364 Inorganic Chemistry, Vol. 35, No. 5, 1996
Crespo et al.
Figure 2. Molecular structure of 7 with the atom-labeling scheme. Phenyl hydrogen atoms are omitted for clarity; radii are arbitrary.
Table 3. Selected Bond Lengths (Å) and Angles (deg) for
Compound 1
formed by their three bonding partners. The proton initially
belonging to the eliminated boron atom is bonded to the central
boron atom of the C2B3 open face.
Au-P(3)
2.2831(13)
2.3952(12)
1.814(5)
1.812(5)
1.832(5)
1.818(5)
Au-P(1)
2.3896(13)
1.808(5)
1.827(5)
1.819(5)
1.809(5)
1.822(5)
Au-P(2)
P(1)-C(11)
P(1)-C(1)
P(2)-C(31)
P(3)-C(61)
P(3)-C(71)
In a similar manner to that observed for complex 1, the Au-P
distances to the phosphorus atoms of the [(Ph2P)2C2B9H10]- are
longer, 2.429(3), 2.365(3), 2.374(3) and 2.443(3) Å, than to the
phosphorus atom of the bridging diphosphine, 2.293(3) and
2.288(3) Å, consistent with the principle that the shortest bond
is opposite the narrowest angle. The chelate rings again display
an envelope conformation, with the gold atoms 0.81 and 0.96
Å out of the plane of the other four atoms. The propyl backbone
of the dppp is extended, with torsion angles -174 and -175°
about C(5)-C(6) and C(6)-C(7) respectively.
P(1)-C(21)
P(2)-C(41)
P(2)-C(2)
P(3)-C(51)
P(3)-Au-P(1)
P(1)-Au-P(2)
C(11)-P(1)-C(1)
C(11)-P(1)-Au
C(1)-P(1)-Au
C(41)-P(2)-C(2)
C(41)-P(2)-Au
C(2)-P(2)-Au
138.67(4) P(3)-Au-P(2)
136.05(4)
84.91(4) C(11)-P(1)-C(21) 103.0(2)
108.1(2)
120.0(2)
106.1(2)
106.5(2)
122.2(2)
106.3(2)
C(21)-P(1)-C(1)
C(21)-P(1)-Au
107.5(2)
111.6(2)
C(41)-P(2)-C(31) 103.7(2)
C(31)-P(2)-C(2)
C(31)-P(2)-Au
109.6(2)
108.2(2)
The treatment of complex 1 with the strong base NaH
deprotonates the cage affording the complex Na[Au{(PPh2)2-
C2B9H9}(PPh3)], which was not isolated. Further reaction with
[Au(PPh3)(tht)]ClO4 gives the complex [Au2{(PPh2)2C2B9H9}-
C(61)-P(3)-C(51) 105.9(2)
C(61)-P(3)-C(71) 103.7(2)
C(51)-P(3)-C(71) 103.9(2)
C(61)-P(3)-Au
C(71)-P(3)-Au
109.6(2)
116.9(2)
C(51)-P(3)-Au
115.6(2)
+
(PPh3)2] (8), where one AuPP3 fragment has an exo-nido
coordination to the phosphorus atoms, and the other has an η5-
coordination to the open C2B3 face. Compound 8 is a yellow
air- and moisture-stable solid, nonconducting in acetone solution.
The IR spectrum shows bands similar to those of the starting
material, with the υ(B-H) absorption at 2526 (s, br) cm-1. In
the 1H NMR spectrum the signal at ca. -2 ppm has disappeared,
and in the 31P{1H} spectrum there are three different phosphorus
enviroments. The exo-nido-phosporus atoms present an AX2
system, thus appearing as a triplet (PPh3) and a doublet for the
In the IR spectra, apart from the typical bands arising from the
diphosphine ligands, the υ(B-H) absorptions appear at 2529
(s, br) and 2531 (s, br) cm-1, respectively.
The partially degraded nature of the carborane in the com-
plexes can be seen in the 1H NMR spectra, which show a pattern
similar to that discussed above for complexes 1-5. The 31P-
{1H} NMR spectra correspond to AX2 systems, and therefore
a triplet and a doublet appear for the two different phosphorus
environments.
In the positive-ion mass spectra (FAB+) the molecular peak
appears only for complex 7 at m/z ) 1809, and then with only
5% intensity; however, the cations arising from the loss of one
negative ligand, [(Ph2P)2C2B9H10]-, are present in both cases
with high intensity.
The structure of complex 7 was confirmed by an X-ray
diffraction study, and the molecule is shown in Figure 2.
Positional parameters are collected in Table 4 and selected bond
lengths and angles in Table 5. The molecule has two gold
atoms, each one bonded to the two phosphorus atoms of the
diphosphine [(Ph2P)2C2B9H10]- and to one of the phosphorus
atoms of the other diphosphine; thus both display a trigonal
planar coordination. The major distortion arises from the
restricted bite of the nido diphosphines, 86.06(10) and 84.35-
(9)°, values of the same order as found in complex 1. The gold
atoms are located 0.023(2) and 0.127(2) Å out of the planes
+
diphosphine phosphorus; the phosphorus atoms of the AuPPh3
group coordinated to the carborane open face appear as a broad
multiplet, as a consequence of the coupling with the boron
nuclei. As far as we are aware this is the first example of a
complex combining coordination to the exo-heteroatoms and
to the carborane moiety, thus forming the first metallocarborane
complex of this ligand.
The mass spectrum also confirms the proposed stoichiometry,
with the molecular peak appearing at m/z ) 1420 (44%), and
+
other fragments corresponding to the loss of AuPPh3 or the
association [M + AuPPh3]+ are present.
Experimental Section
Instrumentation. Infrared spectra were recorded in the range
4000-200 cm-1 on a Perkin-Elmer 883 spectrophotometer using Nujol
mulls between polyethylene sheets. Conductivities were measured in

Gold(I) Metallocarboranes
Inorganic Chemistry, Vol. 35, No. 5, 1996 1365
Table 4. Atomic Coordinates [×104] and Equivalent Isotropic Displacement Parameters [Å2 × 103] for Compound 7
x
y
z
U(eq)
x
y
z
U(eq)
Au(1)
Au(2)
P(1)
P(2)
P(3)
P(4)
P(5)
P(6)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
B(1)
B(2)
B(3)
B(4)
B(5)
B(6)
B(7)
B(8)
B(9)
B(11)
B(12)
B(13)
B(14)
B(15)
B(16)
B(17)
B(18)
B(19)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(31)
C(32)
C(33)
C(34)
C(35)
C(36)
C(41)
C(42)
C(43)
C(44)
C(45)
C(46)
C(51)
C(52)
C(53)
C(54)
C(55)
1999.6(3)
3537.7(4)
304(2)
1022(2)
4108(2)
2796(2)
3822(2)
3710(2)
-629(8)
-286(8)
4319(8)
3693(8)
4331(8)
3839(8)
4359(9)
-1347(10)
-2520(12)
-1910(11)
-2067(11)
-2406(12)
-1210(11)
-150(12)
-660(10)
-1293(11)
3457(10)
4017(10)
4530(10)
4503(11)
4710(11)
5400(10)
5604(11)
5027(10)
5709(11)
85(8)
1377.9(2)
3821.3(2)
1726(2)
1338(2)
4431.1(14)
5070.7(15)
1098.5(14)
2715.6(14)
1341(6)
1188(6)
5312(5)
5625(5)
1104(5)
1844(6)
1881(6)
1320(7)
1528(8)
1553(7)
631(7)
2137.5(2)
3286.1(2)
2937(2)
1312.2(15)
2120.9(14)
3600.8(15)
1943.7(14)
4000.1(14)
2681(6)
1875(5)
2225(5)
2965(5)
2694(5)
2999(5)
3572(6)
1589(7)
2352(8)
3029(7)
2111(7)
3017(8)
3258(8)
2523(7)
1824(7)
2697(7)
2916(7)
2005(7)
1591(7)
3281(7)
2650(7)
1803(7)
1958(7)
2849(7)
2599(7)
3883(6)
4366(6)
5082(6)
5327(7)
4834(6)
4121(6)
2831(5)
2902(6)
2813(8)
2633(7)
2572(6)
2676(6)
712(5)
28.1(1)
27.6(1)
31.1(7)
29.7(7)
24.9(7)
28.3(7)
23.4(6)
22.2(6)
31(3)
28(3)
26(2)
22(2)
25(2)
29(3)
29(3)
32(3)
41(4)
36(3)
40(4)
47(4)
38(4)
41(4)
32(3)
40(4)
31(3)
31(3)
32(3)
37(3)
40(4)
34(3)
36(3)
31(3)
33(3)
37(3)
65(4)
68(4)
60(4)
58(4)
44(3)
34(3)
50(3)
73(4)
70(4)
58(3)
48(3)
37(3)
52(3)
65(4)
58(4)
48(3)
35(3)
38(3)
36(3)
51(3)
62(4)
69(4)
53(3)
26(2)
37(3)
54(3)
50(3)
51(3)
C(56)
C(61)
C(62)
C(63)
C(64)
C(65)
C(66)
C(71)
C(72)
C(73)
C(74)
C(75)
C(76)
C(71′)
C(72′)
C(73′)
C(74′)
C(75′)
C(76′)
C(81)
C(82)
C(83)
C(84)
C(85)
C(86)
C(91)
C(92)
C(93)
C(94)
C(95)
C(96)
C(101)
C(102)
C(103)
C(104)
C(105)
C(106)
C(111)
C(112)
C(113)
C(114)
C(115)
C(116)
C(121)
C(122)
C(123)
C(124)
C(125)
C(126)
O(1)
5067(9)
4497(7)
5548(8)
6054(10)
5509(9)
4479(10)
3963(9)
2581(11)
1679(13)
831(10)
885(11)
1787(13)
2635(11)
2430(11)
1515(15)
519(12)
436(12)
1350(15)
2347(12)
4577(8)
5630(9)
6291(10)
5944(11)
4911(12)
4230(10)
5294(8)
6154(8)
7115(9)
7252(9)
6439(9)
5460(8)
3074(8)
2383(8)
1595(9)
1472(10)
2148(10)
2949(9)
1431(9)
629(9)
19(6)
1701(5)
1748(6)
2184(6)
2573(6)
2540(6)
2106(6)
2432(9)
2988(7)
2858(8)
2171(9)
1615(7)
1745(8)
2595(10)
3077(9)
3027(10)
2496(12)
2013(10)
2063(9)
2741(5)
2795(7)
2875(8)
2901(8)
2858(7)
2788(6)
4069(5)
3582(5)
3362(6)
3633(6)
4112(6)
4321(6)
4593(5)
5267(6)
5334(7)
4734(6)
4064(7)
3998(6)
5477(5)
5157(6)
5400(7)
5967(7)
6290(7)
6051(6)
5219(5)
4714(6)
4821(7)
5420(6)
5914(6)
5819(6)
7072(7)
8093(10)
8114(9)
7720(9)
-822(19)
-739(16)
-312(19)
-131(21)
1383(20)
2149(24)
2182(21)
2389(25)
1065(6)
1214(5)
1126(6)
546(7)
77(6)
140(6)
44(3)
23(2)
36(3)
51(3)
45(3)
50(3)
38(3)
31(7)
34(6)
54(7)
48(7)
53(7)
35(6)
20(6)
54(7)
99(11)
73(9)
66(8)
53(7)
28(2)
58(4)
82(5)
77(4)
60(4)
45(3)
29(2)
34(3)
47(3)
42(3)
40(3)
36(3)
27(2)
33(3)
47(3)
48(3)
52(3)
45(3)
29(2)
42(3)
54(3)
62(4)
55(3)
39(3)
28(2)
42(3)
49(3)
48(3)
40(3)
30(2)
94(4)
98(6)
80(5)
77(5)
333(15)
186(11)
211(13)
221(14)
348(16)
273(18)
239(16)
277(18)
725(6)
4677(7)
4850(8)
5434(8)
5846(7)
5674(8)
5089(8)
4584(8)
4459(8)
4926(11)
5519(10)
5644(8)
5177(9)
4524(5)
4166(7)
4534(9)
5252(8)
5602(7)
5235(6)
1483(5)
1690(6)
1210(6)
504(6)
791(8)
656(7)
436(8)
395(7)
72(8)
6517(7)
6860(7)
5992(7)
5995(7)
6762(8)
6441(7)
5468(7)
5183(7)
5921(7)
1467(6)
1788(7)
1546(8)
1004(7)
715(7)
272(6)
754(5)
1668(5)
1579(5)
1264(6)
1041(6)
1103(6)
1411(6)
3553(5)
4025(6)
3991(7)
3489(7)
3015(7)
3045(6)
4461(5)
4818(5)
5472(6)
5784(6)
5445(6)
4790(5)
1375(6)
830(10)
2017(9)
1430(9)
4881(18)
3970(15)
4066(19)
4434(20)
7794(18)
7073(24)
7798(21)
7769(25)
-793(11)
-945(11)
-205(10)
696(11)
855(9)
-123(8)
564(10)
927(7)
2728(6)
3134(6)
3897(7)
4258(8)
3887(6)
3126(6)
648(6)
-417(9)
-675(11)
133(9)
330(12)
-586(11)
-1291(11)
-1072(9)
1504(8)
1176(9)
2797(8)
3473(9)
3510(10)
2861(9)
2165(9)
2143(8)
1734(9)
697(15)
1160(13)
1225(13)
3661(25)
5108(24)
3373(27)
3951(30)
2718(27)
2650(34)
1560(32)
2551(38)
1078(9)
698(7)
159(8)
161(6)
1437(10)
2213(10)
2646(9)
2277(8)
823(8)
5(9)
-49(10)
712(10)
-293(7)
-169(7)
386(7)
837(5)
734(6)
957(6)
552(7)
-80(7)
-307(7)
91(6)
1708(5)
2170(6)
1990(7)
1351(6)
897(7)
-443(7)
-503(7)
41(6)
2206(7)
2792(6)
3469(6)
3585(8)
2996(8)
2318(7)
170(5)
-405(6)
-1103(6)
-1262(6)
-695(6)
C(200)
C(201)
C(202)
O(2)
C(204)
C(205)
C(206)
O(3)
1509(11)
1599(9)
4359(8)
3934(9)
C(207)
C(208)
C(209)
4248(10)
4959(10)
5370(10)
a U(eq) is defined as one-third of the trace of the orthogonalized Uij tensor.
ca. 5 × 10-4 mol dm-3 solutios with a Philips 9509 conductimeter. C
and H analyses were carried out with a Perkin-Elmer 240C microana-
lyzer. Mass spectra were recorded on a VG autospec, with the FAB
technique, using nitrobenzyl alcohol as matrix. NMR spectra were
recorded on a Varian Unity 300 spectrometer and a Brucker AR X
300 spectrometer, in CDCl3. Chemical shifts are cited relative to SiMe4
(1H), 85% H3PO4 (external, 31P), CFCl3 (external, 19F) and BF3OEt2
(external, 11B). The yields, melting points, analyses, conductivities and
NMR data for the new complexes are listed in Table 1. The yields
correspond to the crude products, they can be recrystallized from CH2-
Cl2/n-hexane.
Materials. [1,2-(PPh2)2-1,2-C2B10H10] was prepared following
literature procedures.23 Complexes [AuClPR3],24 [Au(PPh3)(tht)]ClO4,25
and [Au2Cl2(µ-P-P)] [P-P ) dppe, dppp]26 were also prepared following
literature procedures. Synthesis of [Au{(PPh2)2C2B10H10}(PR3)]ClO4
was carried out as previously described by us.10
(23) Alexander, R. P.; Schoeder, H. Inorg Chem. 1963, 26, 1107.
(24) Uso´n, R.; Laguna, A. Inorg., Synth. 1982, 21, 71.
(25) Uso´n, R.; Laguna, A.; Laguna, M; Jimenez, J.; Go´mez, M. P.; Sainz,
A.; Jones, P. G. J. Chem. Soc., Dalton Trans. 1990, 47, 3457.
(26) Berners-Price, S. J.; Sadler, P. J. Inorg., Chem. 1986, 25, 3822.

1366 Inorganic Chemistry, Vol. 35, No. 5, 1996
Crespo et al.
Table 6. Details of X-ray Structure Analyses for Compounds 1
Table 5. Selected Bond Lengths (Å) and Angles (deg) for
Compound 7
and 7
Au(1)-P(5)
Au(1)-P(2)
Au(2)-P(3)
P(1)-C(11)
P(1)-C(1)
P(2)-C(41)
P(3)-C(91)
P(3)-C(3)
P(4)-C(111)
P(5)-C(51)
P(5)-C(5)
2.293(3)
2.429(3)
2.374(3)
Au(1)-P(1)
Au(2)-P(6)
Au(2)-P(4)
P(1)-C(21)
P(2)-C(31)
P(2)-C(2)
2.365(3)
2.288(3)
2.443(3)
1.822(11)
1.809(11)
1.828(10)
1.817(11)
1.799(11)
1.826(10)
1.816(10)
1‚CH2Cl2
7‚3Me2CO
formula
Mr
C45H47Au3B9Cl2P3
1045.89
yellow tablet
0.4 × 0.4 × 0.2
P21/c
C88H104Au2B18O3P6
1984.04
1.810(11)
1.835(11)
1.821(12)
1.782(11)
1.818(10)
1.823(11)
1.815(10)
1.835(10)
cryst habit
cryst size (mm)
space group
temp (°C)
cell constants
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
yellow tablet
0.65 × 0.5 × 0.25
P1h
P(3)-C(101)
P(4)-C(121)
P(4)-C(4)
-130
-100
17.326(3)
20.688(3)
13.442(2)
90
104.710(12)
120
4660.2
4
1.491
13.432(3)
18.888(3)
20.021(3)
78.56(2)
72.02(2)
75.31(2)
4633.5
2
P(5)-C(61)
P(5)-Au(1)-P(1)
P(1)-Au(1)-P(2)
P(6)-Au(2)-P(4)
C(11)-P(1)-C(21)
C(21)-P(1)-C(1)
C(21)-P(1)-Au(1)
C(31)-P(2)-C(41)
C(41)-P(2)-C(2)
C(41)-P(2)-Au(1)
147.36(10) P(5)-Au(1)-P(2)
86.06(10) P(6)-Au(2)-P(3)
129.81(10) P(3)-Au(2)-P(4)
104.3(5)
108.0(5)
109.8(3)
103.8(5)
108.3(5)
112.4(4)
126.55(10)
144.80(10)
84.35(9)
C(11)-P(1)-C(1)
106.6(5)
Z
C(11)-P(1)-Au(1) 121.4(3)
Dx (Mg m-3
F(000)
)
1.422
1988
C(1)-P(1)-Au(1)
C(31)-P(2)-C(2)
106.2(3)
106.4(5)
2080
µ (mm-1
)
3.4
3.3
C(31)-P(2)-Au(1) 120.9(3)
transm factors
2θmax (deg)
no. of reflcns
measd
0.56-0.98
0.90-0.95
C(2)-P(2)-Au(1)
C(91)-P(3)-C(3)
104.5(3)
104.1(5)
50
45
C(91)-P(3)-C(101) 103.4(5)
C(101)-P(3)-C(3)
109.3(4)
C(91)-P(3)-Au(2) 123.3(3)
9399
8224
0.094
0.095
0.036
508
12863
11742
0.050
0.112
0.053
898
C(101)-P(3)-Au(2) 110.3(3)
C(121)-P(4)-C(111) 104.1(4)
C(3)-P(3)-Au(2)
105.8(3)
indep
Rint
C(121)-P(4)-C(4) 105.6(5)
C(111)-P(4)-C(4)
108.7(4)
C(121)-P(4)-Au(2) 116.8(3)
R(F2, all reflcns)
R(F, F>4σ(F))
no. of params
no. of restraints
S
C(111)-P(4)-Au(2) 116.8(3)
C(4)-P(4)-Au(2)
C(51)-P(5)-C(5)
104.1(3)
104.4(4)
C(51)-P(5)-C(61)
C(61)-P(5)-C(5)
C(61)-P(5)-Au(1)
105.9(4)
105.9(5)
112.9(3)
C(51)-P(5)-Au(1) 110.1(3)
489
729
C(5)-P(5)-Au(1)
116.8(3)
1.09
0.001
0.8
1.08
0.008
1.4
max. ∆/σ
Safety Note. Caution! Perchlorate salts of metal complexes with
organic ligands are potentially explosive. Only small amounts of
material should be prepared, and these should be handled with great
caution.
max. ∆ρ (e Å-3
)
were refined from (ω angles (1) or setting angles (7) of ca. 60
reflections in the 2θ range 20-23° (1) and 10-25° (7). Absorption
corrections were applied on the basis of Ψ-scans.
Structures were solved by the heavy atom method and refined
anisotropically (except B, H, disordered or solvent C/O) on F2 using
the program SHELXL-93.27
Synthesis of [Au{(PPh2)2C2B9H10}(PR3)]. (a) To a suspension of
[AuCl(PR3)] [0.1 mmol; 0.049 g (PR3 ) PPh3), 0.043 g (PR3 ) PPh2-
Me), 0.050 g (PR3 ) PPh2(4-Me-C6H4)), 0.053 g (PR3 ) P(4-Me-
C6H4)3), 0.058 g (PR3 ) P(4-OMe- C6H4)3)] in ethanol (30 mL) was
added [(PPh2)2C2B10H10] (0.1 mmol, 0.051 g). The mixture was
refluxed for 30 min. The complexes, as yellow solids, were collected
by filtration and washed with 10 mL of ethanol. (b) These complexes
can be also synthesized by refluxing a suspension of [Au{(PPh2)2C2-
B10H10}(PR3)]ClO4 [0.1 mmol; 0.107 g (PR3 ) PPh3), 0.100 g (PR3 )
PPh2Me), 0.108 g (PR3 ) PPh2(4-Me-C6H4)), 0.111g (PR3 ) P(4-Me-
C6H4)3), 0.116 g (PR3 ) P(4-OMe-C6H4)3)] in ethanol (30 mL). The
complexes were isolated by filtration. 11B NMR data, δ: (1) -7.7 (s,
br, 2B), -12.7 [d, 3B, J(BH) 103.6 Hz], -16.4 (s, br, 2B), -29.3 (m,
1B), -34.7 [d, 1B, J(BH) 133.2 Hz]; (2) -7.9 (s, br, 2B), -13.7 [d,
3B, J(BH) 101.2 Hz], -17.8 (s, br, 2B), -29.6 (m, 1B), -34.5 [d, 1B,
J(BH) 128.4 Hz]; (3) -8.1 (s, br, 2B), -12.8 [d, 3B, J(BH) 103.8
Hz], -16.6 (s, br, 2B), -29.8 (m, 1B), -34.2 [d, 1B, J(BH) 134.1
Hz]; (5) -7.8 (s, br, 2B), -12.5 (m, 3B), -17.8 (s, br, 2B), -29.7 (m,
1B), -34.3 [d, 1B, J(BH) 130.2 Hz].
Synthesis of [Au2{(PPh2)2C2B9H10}2(µ-P-P)]. As previously de-
scribed, to a suspension of [Au2Cl2(µ-P-P)] [0.1 mmol; 0.084 g, (P-P
) dppe), 0.087 g, (P-P ) dppp)] in ethanol (30 mL) was added
[(PPh2)2C2B10H10] (0.2 mmol, 0.102 g). The mixture was refluxed for
an hour and the complexes separated by filtration and washed with 10
mL of ethanol.
Synthesis of [Au2{(PPh2)2C2B9H9}2(PPh3)2]. To a two-necked
round bottom flask (100 mL) fitted with a dinitrogen inlet/outlet,
containing deoxygenated dry THF (40 mL), were added [Au-
{(PPh2)2C2B9H10)(PPh3)] (0.1 mmol, 0.097 g) and excess NaH. The
mixture was stirred for an hour and the excess NaH filtered off. The
solution was treated with [Au(PPh3)(tht)]ClO4 and stirred for another
hour. Upon addition of n-hexane (15 mL), complex 9 was obtained
as a yellow solid.
Special Details for 1. The structure is pseudosymmetric, the gold
atom lying at y ) ca. 0.5. This causes reflections with h + l odd to
be weak. These reflections were therefore collected again slowly, and
are thus the main contributors to Rint, which is correspondingly high.
All the hydrogen atoms of the carborane moiety were clearly identified
in difference syntheses. The B-H on the open carborane face were
refined freely (although heavily restrained with SADI). Other hydro-
gens atoms were included using a riding model. The dichloromethane
molecule is well-defined.
Special Details for 7. The structure contains three molecules of
acetone, of which however only the first is well defined; the other two
are distorted and probably severely disordered over two alternative
orientations. The phenyl ring C(71)-C(76) is disorded over two
positions. The hydrogen atoms of the open face of the carborane were
identified with difficulty from difference syntheses and refined as above;
their positions should be regarded as tentative. The pattern of H atoms
is however the same as in other analogues. Further details are given
in Table 6.
Acknowledgment. We thank the Direccio´n General de
Investigacio´n Cient´ıfica y Te´cnica (No. PB94-0079) and the
Fonds der Chemischen Industrie for financial support.
Supporting Information Available: Tables of crystal data, data
collection, and solution and refinement parameters, atomic parameters,
bond distances and angles, and anisotropic thermal parameters, and
hydrogen atom parameters for 1 and 7 and a thermal ellipsoid plot for
1 (22 pages). Ordering information is given on any currrent masthead
page.
Crystal Structure Determinations of Complexes 1 and 7. Crystals
were mounted in inert oil on glass fibers. Data were collected using
monochromated MoKR radiation (λ ) 0.710 73 Å). Diffractometer
type: Stoe-STADI-4 (1) and Siemens R3 (7), both with Siemens low
temperature attachment. Scan type ω/θ (1) and ω (7). Cell constants
IC951204X
(27) Sheldrick, G. M. SHELXL-93. A program for Crystal Structure
Refinement; University of Go¨ttingen: Go¨ttingen, Germany, 1993.