Organoindium Thiolate Oligomers: An X-ray Structural Study

Article abstract of DOI:10.1021/om990887b

The reaction of R₃In (R = methyl, tert-butyl, xylyl) with bis(tricyclohexyltin) sulfide, 2-methylpropane-2-thiol, 4,6-dimetnyl-2-mercaptopyrimidine, cyclopentanethiol, cyclohexanethiol, 2,5-dimethylbenzenethiol, or 2,6-methylbenzenethiol has yi

Full text of DOI:10.1021/om990887b

Organometallics 2000, 19, 865-871
865
Or ga n oin d iu m Th iola te Oligom er s: An X-r a y Str u ctu r a l
Stu d y
Burl Yearwood, Shahid Ul Ghazi, Mary J ane Heeg, Nicholas Richardson, and
J ohn P. Oliver*
Department of Chemistry, Wayne State University, Detroit, Michigan 48202
Received November 4, 1999
The reaction of R3In (R ) methyl, tert-butyl, xylyl) with bis(tricyclohexyltin) sulfide,
2-methylpropane-2-thiol, 4,6-dimethyl-2-mercaptopyrimidine, cyclopentanethiol, cyclohex-
anethiol, 2,5-dimethylbenzenethiol, or 2,6-methylbenzenethiol has yielded seven new in-
dium-sulfur complexes: {m-Xyl2In[µ-SSn(C6H11)3]}2 (2), [t-Bu2In(µ-S-C5H9)]2 (3), [t-Bu2In(µ-
S-C6H11)]2 (4), {t-Bu2In[µ-S(2,5-Me2)C6H3]}2 (5), [Me2In(µ-S-t-Bu)]3 (6), {t-Bu2In[µ-S(4,6-
Me2)C4N2H]}3 (7), and {Me2In[µ-S(2,6-Me2)C6H3]}4 (8). These complexes have been studied
1
by H and 13C NMR spectroscopy, and their structures have been determined by single-
crystal X-ray diffraction techniques. 2-5 form dimeric species with planar (In-S)2 cores, 6
forms a trimer which adopts a skew-boat conformation, 7 forms a trimer with a planar six-
membered (InS)3 ring with a secondary In-N interaction, giving rise to a pseudo-five-
coordinate In atom, and 8 forms a tetramer in an extended chair conformation, the first
known indium tetramer. Several of the factors of importance to the structures of these
compounds, and especially those which lead to the unusual planar derivative 7, will be
discussed.
In tr od u ction
(R3Si)2E,12 and R2S2.13 On the basis of successful tech-
niques employed in the synthesis of gallium-chalco-
genide oligomers, we have attempted to extend these
procedures to the synthesis of indium-chalcogenide
oligomers.3,7 The few structural studies reported show
most of these compounds are dimers with (InE)2 central
rings.3,4,6,10,14 Polymers14,15 and one trimer4 have also
been reported. With this information in hand we have
started a search for other aggregation states and
structure types by studying the effects of the organic
moiety on the molecules.
In this paper, we report the synthesis of m-Xyl3In (1)
and the synthesis and X-ray studies of seven new
indium-sulfur compounds: {m-Xyl2In[µ-SSn(C6H11)3]}2
(2), [t-Bu2In(µ-S-C5H9)]2 (3), [t-Bu2In(µ-S-C6H11)]2 (4), {t-
Bu2In[µ-S(2,5-Me2)C6H3]}2 (5), [Me2In(µ-S-t-Bu)]3 (6), {t-
Bu2In[µ-S(4,6-Me2)C4N2H]}3 (7), and {Me2In[µ-S(2,6-
Me2)C6H3]}4 (8). The synthesis of 3-8 utilizes R3In, with
the elimination of RH upon addition of a ligand. The
synthesis of 2 was accomplished by the reaction of bis-
(tricyclohexyltin) sulfide with Xyl3In.
With the continuing interest in the use of group 13-
16 organometallic compounds for the preparation of thin
films or other materials, there have been extensive
studies in the structures and dynamic properties of
aluminum and gallium compounds.1-8 This research has
resulted in the discovery of various aggregation states
and structures for complexes of these metals. While it
is known that thin films of the type InxSy have interest-
ing, and potentially useful, electrical, optical, and pho-
tovoltaic properties, little work has been done on the
characterization of potential precursors for these ma-
terials. It is the behavior of the compounds in the gas
phase, in solution, or in the solid state which frequently
determines the reactions of these derivatives and the
nature of the products obtained. Reported synthetic
methods for the preparation of indium complexes have
included the insertion of a chalcogen into an In-In
bond,9 preparation of complexes by stoichiometric ligand
redistributions,10 the reaction of R3In with R2Te2,6 and
the reactions of X2InR (where X ) Cl, Br, I) with REH,11
(1) Oliver, J . P.; Kumar, R.; Taghiof, M. The Chemistry of Alkoxides,
Thiolates, and the Heavier Group 16 Derivatives of Aluminum and
Gallium; Robinson, G. H., Ed.; VCH: New York, 1993; pp 167-195.
(2) Oliver, J . P.; Kumar, R. Polyhedron 1990, 9, 409.
(3) Ghazi, S. U.; Heeg, M. J .; Oliver, J . P. Inorg. Chem. 1994, 33,
4517.
(4) Rahbarnoohi, H.; Taghiof, M.; Heeg, M. J .; Dick, D. G.; Oliver,
J . P. Inorg. Chem. 1994, 33, 6307.
(5) Keller, H.; Daran, J . C.; Lang, H. J . Organomet. Chem. 1994,
482, 63.
(6) Rahbarnoohi, H.; Kumar, R.; Heeg, M. J .; Oliver, J . P. Organo-
metallics 1995, 14, 502.
(7) Taghiof, M.; Heeg, M. J .; Bailey, M.; Dick, D. G.; Kumar, R.;
Hendershot, D. G.; Rahbarnoohi, H.; Oliver, J . P. Organometallics
1995, 14, 2903.
(8) Oliver, J . P. J . Organomet. Chem. 1995, 500, 269.
(9) Uhl, W.; Graupner, R.; Reuter, H. J . Organomet. Chem. 1996,
523, 227.
Exp er im en ta l Section
Gen er a l P r oced u r es. All solvents were purified and dried
by standard techniques.16 Argon gas was purified by passing
(10) Beachley, O. T., J r.; Lee, J . C., J r.; Gysling, H. J .; Chao, S.-H.
L.; Churchill, M. R.; Lake, C. H. Organometallics 1992, 11, 3144.
(11) Hoffmann, G. G.; Faist, R. J . Organomet. Chem. 1990, 391, 1.
(12) Hoffmann, G. G.; Fischer, R. Phosphorus, Sulfur Silicon Relat.
Elem. 1989, 41, 97.
(13) Hoffmann, G. G. Z. Naturforsch. 1984, 39B, 352.
(14) Rahbarnoohi, H.; Kumar, R.; Heeg, M. J .; Oliver, J . P. Orga-
nometallics 1995, 14, 3869.
(15) Annan, T.; Kumar, R.; Mabrouk, H. E.; Tuck, D. G.; Chadha,
R. K. Polyhedron 1989, 8, 865.
(16) Shriver, D. F.; Drezdzon, M. A. The Manipulation of Air-
Sensitive Compounds; Wiley: New York, 1986.
10.1021/om990887b CCC: $19.00 © 2000 American Chemical Society
Publication on Web 02/09/2000

866 Organometallics, Vol. 19, No. 5, 2000
Yearwood et al.
it through a series of columns containing Deox catalyst (Alfa),
phosphorus pentoxide, and sodium hydroxide. Bis(tricyclo-
hexyltin) sulfide (Aldrich), 2-methylpropane-2-thiol (Aldrich),
4,6-dimethyl-2-mercaptopyrimidine (Aldrich), cyclopentaneth-
iol (Aldrich), cyclohexanethiol (Aldrich), 2,5-dimethylben-
zenethiol (Aldrich), and 2,6-methylbenzenethiol (Aldrich) were
purchased and used as received. Trimethylindium etherate
and tri-tert-butylindium were prepared according to the pub-
lished procedures.17,18 The compounds are both water- and
oxygen-sensitive; therefore, standard Schlenk line and glove-
box techniques were employed. All of the glassware used in
P r ep a r a tion of [t-Bu 2In (µ-S-C6H11)]2 (4). Cyclohexaneth-
iol (0.21 mL, 1.75 mmol) was added to t-Bu3In (0.50 g, 1.75
mmol) in toluene/hexane (40 mL, 80:20). The crystalline solid
was identified as 4 from X-ray, MS, NMR, and elemental
analysis. The NMR of the crystalline solid was identical with
that of the white solid initially formed. Yield: 85%. Mp: 190-
192 °C. Anal. Calcd (found) for C14H29SIn: C, 48.84 (48.00);
1
H, 8.49 (8.74). H NMR (C6D6; δ, ppm): 1.10 (4H, m, SC6H11);
1.35 (2H, m, SC6H11); 1.47 (18H, s, In(C(CH3)3)2); 1.59 (2H, m,
SC6H11); 1.90 (2H, m, SC6H11); 3.31 (1H, m, SC6H11). 13C{1H}
NMR (C6D6; δ, ppm): 25.7 (C4 of SC6H11); 26.7 (C3, C5 of
SC6H11); 33.1 (C(CH3)3)2); 39.5 (C2, C6 of SC6H11); 41.5 (C-1 of
SC6H11). Mass spectrum (EI mode): m/e 631 [C24H49In2S2]•+
1
the synthetic work was oven- and/or flame-dried. H and 13C
NMR spectra were recorded on General Electric QE-300 or QN-
1
300 or Varian Unity 500 NMR spectrometers. The H and 13C
(dimer - t-Bu), 574 [C20H40In2S2]•+, 344 [C14H29InS]•+
.
1
chemical shifts were referenced to benzene (δ 7.15 ppm for H
P r ep a r a tion of {t-Bu 2In [µ-S(2,5-Me2)C6H3]}2 (5). 2,5-
Dimethylbenzenethiol (0.19 mL, 1.40 mmol) was added to
t-Bu3In (0.400 g, 1.40 mmol) in hexane (40 mL). The crystalline
solid was identified as 5 by X-ray, MS, and NMR. Yield: 77%.
and δ 128.00 ppm for 13C). Elemental analyses were performed
by Galbraith Laboratories, Knoxville, TN. Melting points were
recorded on a Haake-Buchler apparatus in sealed capillaries
and are uncorrected.
1
Mp: 179-181 °C. H NMR (C6D6; δ, ppm): 1.32 (18H, s, In-
P r ep a r a tion of m -Xyl3In (1). Indium metal (1.0 g, 8.70
mmol) was added to dixylylmercury (5.37 g, 13.06 mmol) in
100 mL of toluene. The mixture was placed under conditions
of reflux for 72 h. After this time, no observable indium
remained. The solution was transferred while still hot to a
flask with use of a cannula. When the solution was cooled to
room temperature, colorless crystals were deposited. Yield:
96%. Mp: 187 °C. Anal. Calcd (found) for C24H27In: C, 66.99
(C(CH3)3)2); 2.20 (3H, s, 2-CH3 of C6H3); 2.25 (3H, s, 5-CH3 of
C6H3); 6.50 (1H, m, H6 of C6H3); 6.65 (2H, m, H3, H4 of C6H3).
13C{1H} NMR (C6D6; δ, ppm): 21.1 (2-CH3); 22.2 (5-CH3); 33.2
(C(CH3)3)2); 127-128 (C6H3). Mass spectrum (EI mode): m/e
675 [C28H45In2S2]•+ (dimer - t-Bu), 618 [C24H36In2S2]•+, 603
[C23H33In2S2]•+, 329 [C14H14InS]•+, 314 [C13H11InS]•+, 277 [C10H10
-
InS]•+. Exact mass of monomer [C16H27InS]•+ calcd (obsd):
366.2736 (366.2744).
1
(64.48); H, 6.32 (6.21). H NMR (C6D6; δ, ppm): 7.50 (s, 6H)
P r ep a r a tion of [Me2In (µ-S-t-Bu )]3 (6). 2-Methylpro-
panethiol (0.60 mL, 5.30 mmol) was added to 5.00 mL of
trimethylindium etherate (20% Me3In, 5.30 mmol of Me3In)
in pentane (ca. 35 mL). The solid was identified as 6 by X-ray,
MS, and NMR. Yield: 81.9%. Mp: 90-91 °C. 1H NMR (21 °C,
C6D6; δ, ppm): 0.276 (6H, s, broad, Me2In); 1.278 (9H, s, SC-
(CH3)3). 13C{1H} NMR (C6D6; δ, ppm): 1.04 (Me2In); 35.6 (SC-
(CH3)3); 94.8 (SC(CH3)3). Mass spectrum (EI mode): m/e 687
[C17H42In3S3]•+ (trimer - Me), 453 [C11H27In2S2]•+ (dimer -
[C6H3(CH)2]3, 6.88 (s, 3H) [C6H3(CH)2]3, 2.17 (s, 18H) [C6H3-
(CH)2]3. Mass spectrum (EI mode): m/e 430 Xyl3In+ , 325 Xyl2-
+
In+, 211 Xyl2
.
P r ep a r a tion of {m -Xyl2In [µ-SSn (C6H11)3]}2 (2). Bis(tri-
cyclohexyltin) sulfide (0.62 g, 0.81 mmol) was added to 1 (0.35
g, 0.81 mmol) in pentane (ca. 60 mL). The mixture was stirred
until all the reactants were dissolved and a precipitate was
formed (ca. 3 min). The precipitate was dissolved by adding
toluene (10 mL) and warming the mixture to 70 °C. The
solution was cooled to 4 °C and allowed to remain at that
temperature for 24 h, after which time the crystals formed
were isolated at 0 °C, washed with pentane, and dried under
vacuum. Yield: 75%. Mp: 187 °C. Anal. Calcd (found) for
C34H51SInSn: C, 56.30 (56.08); H, 7.09 (7.12). 1H NMR (C6D6;
δ, ppm): 7.81 (s, 4H) [o-H, m-Xyl]; 6.91 (s, 2H) [p-H, m-Xyl];
2.33 (m, 12H) [CH3 of m-Xyl]; 1.09-2.18 (m, 33H) [SSn-
(C6H11)3]. 13C{1H} NMR (C6D6, δ, ppm) 137.0, 136.9, 136.5,
130.1 [m-Xyl]; 33.7, 33.3, 32.7, 32.5, 29.8, 29.4, 27.5, 27.2 [SSn-
(C6H11)3]; 21.6 [CH3 of m-Xyl]. Mass spectrum (EI mode): m/e
363 (C6H11)3Sn+, 281 (C6H11)2Sn+, 196 C6H11Sn+, 120 Sn+.
P r ep a r a tion of [t-Bu 2In (µ-S-C5H9)]2 (3). Cyclopentaneth-
iol (0.19 mL,1.75 mmol) was added to a yellow solution of t-Bu3-
In (0.50 g, 1.75 mmol) in a mixture of toluene and hexane (40
mL, 80:20). The solution became colorless on addition of the
thiol. The solution was stirred for 24 h and then placed at -20
°C for 1 week. The solvent layer was removed under vacuum,
leaving behind a white crystalline precipitate. This solid was
recrystallized from toluene. The solid was identified as 3 from
X-ray, MS, NMR, and elemental analysis. Yield: 85%. Mp: 148
°C. Anal. Calcd (found) for C13H27SIn: C, 47.28 (47.24); H, 8.24
(8.52). 1H NMR (C6D6; δ, ppm): 1.33 (4H, m, SC5H9); 1.45 (18H,
s, In(C(CH3)3)2); 1.48 (2H, m, SC5H9); 1.83 (2H, m, SC5H9); 3.69
(1H, m, SC5H9). 13C{1H} NMR (C6D6; δ, ppm): 25.06 (C3, C4
of CypS); 33.15 (C(CH3)3)2); 36.07 (C(CH3)3)2); 40.02 (C2, C5
of CypS); 41.83 (C1 of CypS). Mass spectrum (EI mode): m/e
603 [C22H45In2S2]•+ (dimer - t-Bu), 559 [C21H45In2S] •+, 330
Me), 234 [C6H15InS]•+, 163 [MeInSH]•+
.
P r ep a r a tion of {t-Bu 2In [µ-S(4,6-Me2)C4N2H]}3 (7). 4,6-
Dimethyl-2-mercaptopyrimidine (2-mpym ) 2-mercaptopyri-
midine; 0.132 g, 0.944 mmol) was added to t-Bu3In (0.270 g,
0.944 mmol) in 30 mL of toluene. The crystals were identified
as 7 from X-ray, MS, NMR, and elemental analysis. Yield:
80%. Mp: 181-183 °C. Anal. Calcd (found) for C14H25N2SIn:
1
C, 45.66 (44.37); H, 6.84 (6.63). H NMR (C6D6; δ, ppm): 1.33
(18H, s, In(C(CH3)3)2); 1.73 (6H, s, 4-CH3, 6-CH3 of 2-mpym);
5.66 (1H, s, 2mpym H). 13C{1H} NMR (C6D6; δ, ppm): 22.78
(2-mpym CH3), 32.20 (In(C(CH3)3)2); 35.08 (C(CH3)), 113.12 (C2
and C4 of mpym). Mass spectrum (EI mode): m/e 382 [C15H27
-
InN2S]•+. Exact mass of monomer [C14H25InN2S]•+ calcd
(obsd): 368.077 (368.077).
P r ep a r a tion of {Me2In [µ-S(2,6-Me2)C6H3]}4 (8). 2,6-
Dimethylbenzenethiol (0.71 mL, 5.3 mmol) was added to 5.00
mL of trimethylindium etherate (20% Me3In, 5.3 mmol of Me3-
In) in pentane (ca. 35 mL). The product was washed twice with
pentane (40 mL), dried under a vacuum, and identified as 8
by X-ray, MS, NMR, and elemental analysis. Yield: 51.7%.
Mp: 142-143 °C. Anal. Calcd (found) for C10H15SIn: C, 42.58
1
(42.10); H, 5.36 (5.32). H NMR (C6D6; δ, ppm): 0.046 (6H, s,
broad, Me2In); 2.51 (6H, s, 2-CH3, 6-CH3); 6.87 (3H, s, C6H3).
13C{1H} NMR (C6D6; δ, ppm): -3.1 (Me2In); 24.07 (2,6-Me2);
127-128 (C6H3). Mass spectrum (EI mode): m/e 549 [C19H27
In2S2]•+ (dimer - Me), 534 [C18H24In2S2]•+, 282 [C10H15InS]•+
(monomer), 267 [C9H12InS]•+
-
.
X-r a y Str u ctu r e Deter m in a tion of 2-8. Crystals were
obtained as described above. A suitable crystal of each
compound was chosen and mounted in a thin-walled capillary
tube within a drybox. This tube was thermally sealed, mounted
upon a goniometer head, and placed on either a Nicolet P21
[C13H27InS]•+, 228 [C8H17In]•+
.
Compounds 4-8 were also synthesized by this general
procedure. Therefore, only essential information is provided
for these syntheses.
(17) Leman, J . T.; Barron, A. R. Organometallics 1989, 8, 2214.
(18) Freeman, D. L.; Odom, J . D.; Nutt, W. R.; Lebioda, L. Inorg.
Chem. 1997, 36, 2718.
(19) SMART/ SAINT; Siemens Analytical X-ray Instruments, Inc.:
Madison, WI, 1996.

Organoindium Thiolate Oligomers
Organometallics, Vol. 19, No. 5, 2000 867
Ta ble 1. Selected Exp er im en ta l P a r a m eter s for th e X-r a y Diffr a ction Stu d y of th e Com p ou n d s
[m -Xyl2In (µ-SSn (C6H11)3)]2 (2), [t-Bu 2In (µ-S-C5H9)]2 (3), [t-Bu 2In (µ-S-C6H11)]2 (4), {t-Bu 2In [µ-S(2,5-Me2)C6H3]}2
(5), [Me2In (µ-S-t-Bu )]3 (6), {t-Bu 2In [µ-S(4,6-Me2)C4N2H]}3 (7), a n d {Me2In [µ-S(2,6-Me2)C6H3]}4 (8)
2
3
4
5
6
7
8
formula
mol wt
C
725.3
34H51SInSn
C13H27SIn
330.22
C14H29SIn
344.25
C16H27SIn
366.26
C6H15SIn
234.06
C14H25N2SIn
368.24
C10H15SIn
282.10
space group
a (Å)
b (Å)
P21/n (No. 14)
16.365(3)
11.890(2)
18.339(2)
90
105.440(1)
90
3432.2(2)
1.404
P21/c (No. 14)
9.1128(3)
17.8423(7)
20.5846(8)
90
100.2280(10)
90
3293.7(2)
1.332
P1h
P1h (No. 2)
8.6360(5)
11.0135(7)
11.2653(9)
114.053(2)
107.9190(10)
97.0860(10)
892.00(10)
1.364
P21/c (No. 14)
9.834(3)
19.108(4)
15.812(2)
90
102.74
90
2898.1(11)
1.609
295(2)
P63m (No. 176)
15.9535(3)
15.9535(3)
13.1476(3)
90
90
120
2897.94(10)
1.266
295(2)
P1h (No. 2)
10.795(2)
11.374(2)
11.652(2)
100.23(3)
115.02(3)
106.09(3)
1172.0(4)
1.599
9.8763(6)
11.9433(8)
15.1396(10)
76.5370(10)
78.2090(10)
87.8110(10)
1700.0(2)
1.345
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
calcd density (g/cm3)
temp (K)
linear abs coeff (µ)
295(2)
1.480
295(2)
1.537
295(2)
1.492
295(2)
1.427
181(2)
2.145
2.584
1.320
(mm-1
)
R1 (I > 2σ(I))
wR2 (I > 2σ(I))
3.57
3.60
4.67
10.05
4.42
8.27
2.41
5.46
5.48
9.95
5.23
13.59
9.98
32.01
diffractometer (2, 6), a Siemens R4/CCD SMART/SAINT
system19 (3-5, 7), or a Siemens R3 diffractometer (8). For 2,
3, and 6, the crystals were assigned to the monoclinic system
on the basis of systematic absences, space group P21/n (No.
14) for 2 and P21/c (No. 14) for 3 and 6. 7 was assigned to the
hexagonal system, space group P63/m (No. 176), and 4, 5, and
8 were assigned to the triclinic system and were successfully
solved in space group P1h (No. 2). No corrections for secondary
extinction were made. Absorption corrections were semiem-
pirical from Ψ-scans for 2, 6, and 8 and were performed by
multiscan techniques with Sheldrick’s program SADABS20 for
3-5 and 7.
Data reductions and full-matrix least-squares refinements
were carried out using the SHELXTL PC21 program for 2, 6,
and 8. Data reductions and full-matrix least-squares refine-
ments were carried out using the SHELX-8622 and SHELXL-
9323 programs for 3-5 and 7. The direct methods routines
produced solutions for the structures, yielding positions for
some of the non-hydrogen atoms, while other atoms were
located during subsequent refinements. Hydrogen atoms were
observed or placed in calculated positions and allowed to ride
on the carbon atoms to which they were bound. For 3 there
was disorder in the cyclopentyl rings. Partial occupancy factors
were used for carbon atoms 3, 4, 8, and 9 to resolve this, with
occupancy factors set to 50%. For 7 there was disorder in the
tert-butyl groups which did not improve when the space group
was lowered. Partial occupancy factors were used for carbon
atoms 8, 9, and 10 to resolve this, with occupancy factors set
to 50%. Selected parameters from the crystal structure deter-
mination are shown in Table 1.
F igu r e 1. Diagram of [m-Xyl2In(µ-SSn(C6H11)3)]2 (2; 0%
thermal ellipsoids) showing the atom-labeling scheme.
Hydrogen atoms have been omitted for clarity.
forming a distorted tetrahedron. The angles around the
In atom range from approximately 130° for C-In-C to
approximately 87° for S-In-S and In-S-In. The
angles around the S atom range from 89 to 116° in 2-5
(Table 2). A comparison of the bond distances and angles
of 2-5 with those of other dimeric group 13 derivatives
is given in Table 3. The sum of the angles around S is
nearly equivalent, with an average value of 316.9° in
2-5 (Table 3), which clearly indicates the pyramidal
nature of the sulfur atom. The sum of these angles is
similar to those reported for the majority of indium, as
well as aluminum and gallium, thiolate dimers and
serves as a sensitive measure of the pyramidal character
of the sulfur or other chalcogen atom in the bridging
site.
The internal angles in the ring are all near 90°, and
all the bond distances are similar, giving essentially
square systems. The only indium thiolates for which this
is not the case are [Me2In(µ-SSiPh3)]3, where the
S-In-S angle is 77.8° with an In-S-In angle of 102.2°,
and [Mes2In(µ-S-t-amyl)]2,4 where the corresponding
angles are 84.2 and 95.9°. In these cases very bulky
groups are attached to both the In and the S atoms and
appear to distort the central square, elongating it along
the In-In axis.
Resu lts a n d Discu ssion
The structures of compounds 2-5 are dimeric with a
central four-membered (In-S)2 planar ring which is
essentially square. This is shown in Figure 1 for 2. In
each case the SR groups are oriented so that the
substituents on the S atoms are in the anti configura-
tion. Selected bond distances and angles for 2-5 are
listed in Table 2 and are in the normal range for indium
thiolates. In all cases the In atoms are four-coordinate
surrounded by two sulfur atoms and two carbon atoms,
(20) Sheldrick, G. M. SADABS, a Program for Absorption Correction
of Siemens Area Detector Data; University of Go¨ttingen, Go¨ttingen,
Germany, 1996.
(21) SHELXTL PC; Siemens Analytical X-ray Instruments, Inc.,
Madison, WI, 1990.
(22) Sheldrick, G. M. SHELX-86; University of Go¨ttingen, Go¨ttingen,
Germany, 1986.
(23) Sheldrick, G. M. SHELXL-93; University of Go¨ttingen, Go¨ttin-
gen, Germany, 1993.
Examination of the In-S bond distances indicates
that they are slightly altered by the substituents bound

868 Organometallics, Vol. 19, No. 5, 2000
Yearwood et al.
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles (d eg) for [m -Xyl2In (µ-SSn (C6H11)3)]2 (2),
[t-Bu 2In (µ-S-C5H9)]2 (3), [t-Bu 2In (µ-S-C6H11)]2 (4), a n d {t-Bu 2In [µ-S(2,5-Me2)C6H3]}2 (5)
2
3
4
5
Bond Distances
In(1)-S(1)
2.557(2) In(1)-S(2)
2.576(1) In(1)-S(1)
In(2)-S(2)
2.5930(14) In(1)-S(1)
2.5992(13) In(1)-S(1)#1
2.5950(13) In(2)-S(2)
2.5956(14) In(2)-S(2)#2
2.602(2)
2.6081(13) In(1)-S(1)
2.606(2)
In(1)-S(1)#1
2.6212(6)
2.6460(5)
In(1)-S(1A)
In(2)-S(1)
2.6079(12)
In(1)-C(1)
In(1)-C(9)
2.141(5) In(1)-C(11)
2.143(5) In(1)-C(15)
In(2)-C(19)
2.189(6)
2.200(5)
2.193(5)
2.206(5)
1.838(5)
1.829(5)
In(1)-C(7)
In(1)-C(11)
In(2)-C(25)
In(2)-C(21)
S(1)-C(1)
2.186(6)
2.208(6)
2.197(6)
2.197(7)
1.838(6)
1.843(6)
In(1)-C(13)
In(1)-C(9)
2.202(2)
2.217(2)
In(2)-C(23)
Sn(1)-S(1)
Sn(1)-C(17)
Sn(1)-C(23)
Sn(1)-C(29)
2.448(2) S(1)-C(1)
2.168(6) S(2)-C(6)
2.170(5)
S(1)-C(1)
1.786(2)
S(2)-C(15)
2.161(5)
Bond Angles
S(1)-In(1)-S(1A)
91.4(5)
S(2)-In(1)-S(1)
S(2)-In(2)-S(1)
87.31(4)
87.35(4)
92.59(4)
92.75(4)
S(1)-In(1)-S(1)#1
S(2)-In(2)-S(2)#2
In(1)-S(1)-In(1)#1
In(2)-S(2)-In(2)#2
C(7)-In(1)-C(11)
C(27)-In(2)-C(21)
C(1)-S(1)-In(1)
88.74(4)
88.50(4)
91.26(4)
91.50(4)
125.2(2)
125.9(3)
115.6(2)
108.4(2)
114.3(2)
S(1)#1-In(1)-S(1)
87.67(2)
In(1)-S(1)-In(1A) 88.6(1)
In(2)-S(1)-In(1)
In(1)-S(2)-In(2)
In(1)#1-S(1)-In(1) 92.33(2)
C(13)-In(1)-C(9) 123.96(9)
C(1)-In(1)-C(9)
Sn(1)-S(1)-In(1)
130.5(2) C(11)-In(1)-C(15) 124.7(2)
116.0(1) C(1)-S(1)-In(2)
111.1(2)
113.7(2)
Sn(1)-S(1)-In(1A) 114.1(1) C(1)-S(1)-In(1)
C(1)-S(1)-In(1)#1
C(15)-S(2)-In(2)
C(15)-S(2)-In(2)#2 110.23(14)
Ta ble 3. Selected Bon d Dista n ces (Å) a n d An gles (d eg) Obser ved in [m -Xyl2In (µ-SSn (C6H11)3)]2 (2),
[t-Bu 2In (µ-S-C5H9)]2 (3), [t-Bu 2In (µ-S-C6H11)]2 (4), {t-Bu 2In [µ-S(2,5-Me2)C6H3]}2 (5), a n d Oth er Selected Gr ou p
13 Th iola te Der iva tives
M-E
(Å)
E-M-E
(deg)
M-E-M
(deg)
sum of angles
around E (deg)
M-C
(Å)
C-M-C
(deg)
compd
[m-Xyl2In(µ-SSn(C6H11)3)]2 (2)a
[t-Bu2In(µ-S-C5H9)]2 (3)a
2.57
2.60
2.61
2.63
2.55
2.50
2.59
2.73
2.72
2.74
2.92
2.91
2.38
2.36
2.39
2.39
2.38
2.39
2.34
2.38
91.4
87.3
88.7
87.7
90.7
77.8
84.2
90.2
90.5
89.6
92.5
92.2
89.1
87.6
86.4
93.8
90.8
92.05
93.5
88.6
88.6
92.7
91.3
92.3
89.3
102.2
95.9
89.8
88.7
86.1
87.5
87.8
90.9
92.2
92.0
86.2
89.2
87.05
86.5
91.4
318.7
316.5
315.3
317.2
311.9
352.1
324.0
292.5
292.3
295.2
285.7
274.4
306.0
330.5
316.5
300.2
313.4
297.9
313.0
322.1
2.14
2.20
2.20
2.21
2.15
2.18
2.23
2.17
2.18
2.16
2.18
2.16
1.98
1.93
1.97
1.95
1.96
1.96
1.96
1.97
130.5
124.6
125.5
124.0
116.3
128.3
111.8
121.5
119.5
133.6
121.9
122.1
119.6
120.0
120.2
126.3
118.2
121.0
114.5
124.6
[t-Bu2In(µ-S-C6H11)]2 (4)a
[t-Bu2In[µ-S(2,5-Me2)C6H3]}2 (5)a
b
{Ph2In[µ-SSn(C6H11)3]}2
c
[Mes2In(µ-SSiPh3)]2
c
[Mes2In(µ-S-t-amyl)]2
d
[Mes2In(µ-SePh)]2
d
[Mes2In(µ-SeMes)]2
e
[Np2In(µ-SePh)]2
f
[Mes2In(µ-TePh)]2
f
[Mes2In(µ-Te-n-Pr)]2
g
[Mes2Al(µ-SBz)]2
g
[Me2Al(µ-SSiPh3)]2
g
[Mes2Al(µ-SPh)]2
h
[Me2Ga(µ-SC5H9)]2
h
Ph2Ga(µ-S-SiMe3)]2
h
[Ph2Ga(µ-SC5H9)]2
b
{Ph2Ga[µ-SSn(C6H11)3]}2
h
{µ-Xyl2Ga[µ-SSi(C6H11)3]}2
a
b
d
g
h
This work. Reference 3. c Reference 4. Reference 14. e Reference 10. f Reference 6. Reference 7. Reference 25.
to the sulfur atom. The In-S distances lie in the range
2.59-2.61 Å when the substituent bound to the S atom
is aliphatic. For the one aromatic derivative reported,
the distance is 2.63 Å, while for the two derivatives with
the S bound to an Sn atom, the values are 2.57 Å in 2
and 2.55 Å in [Ph2In(µ-SSn(C6H11)3)]2.3 These data are
summarized in Table 3.
substituent bound to the sulfur would show a further
decrease in the S-C bond distance and a corresponding
increase in the In-S bond distance. If the suggestion is
that these changes are related to bond strengths, then
one would expect decreased stability for the (In-S)2 ring
as a function on the substituent bound to S. This
remains to be tested experimentally.
We also see modest changes in the S-C bond dis-
tances. As we go from 3 and 4 to 5, the hybridization of
the carbon atom bound to the sulfur atom changes from
sp3 to sp2. With this change, the S-C bond distance
decreases from 1.84 to 1.79 Å, which can be associated
with an increase in the bond strength. Along with this
decrease in the S-C bond distance, there is also an
increase in the In-S bond distance from 2.61 to 2.63 Å,
which can be thought of as a decrease in the bond
strength. One would expect that use of an ethynyl
The C-M-C exocyclic angle appears to be determined
primarily by the organic substituent bound to the
indium. For compounds 3-5 with tert-butyl substitu-
ents, this angle varies over the narrow range of 124-
125.5°. In 2, where both substituents are changed, the
angle increases to 130.5°. If we examine the eight
mesityl derivatives listed in Table 3, six have exocyclic
angles that fall in the very narrow range 119.6-122.1°.
The two which fall outside of this are the SSiPh3
derivative, with a 128.3° angle, and [Mes2In(µ-amyl)]2,

Organoindium Thiolate Oligomers
Organometallics, Vol. 19, No. 5, 2000 869
with an angle of 111.8°. Two of the four phenyl deriva-
tives listed also fall in this range, with the other two
having slightly smaller C-M-C angles. This indicates
that the primary concern is the organic substituent but
also shows additional steric effect from the bridging
ligands influencing this angle.
If we now examine the trends that occur as the
chalcogen or the group 13 metal is changed, we find that
the general structures remain the same. The dominant
species remains dimeric with a planar or near-planar
central four-membered ring. For the indium-selenium
derivatives, there are two compounds with planar
structures ([Mes2In(µ-SePh)]2 and [Mes2In(µ-SeMes)]2)14
and two which have slightly puckered (In-Se)2 rings
([Np2In(µ-SePh)]210 and Np2In(µ-SePh)(µ-P-t-Bu2)InNp2),24
with the planar systems adopting a square configura-
tion. For the indium-tellurium dimers [Mes2In(µ-
TePh)]2 and [Mes2In(µ-Te-n-Pr)]2 these again show a
planar (In-Te)2 core, which is slightly distorted with a
Te-In-Te angle of 92.2-92.5°.6 For the dimeric indium
compounds, it is easily seen that the normal trend is
observed with the pyramidal character of the chalcogen
increasing in the order S < Se < Te. For comparison
some aluminum and gallium derivatives are also shown
in Table 3.
{m-Xyl2Ga[µ-SSn(C6H11)3]}2 has the same general
structural features as 2 with a planar ring slightly
skewed from square (the S-Ga-S angle is 91.4°), and
shorter S bond distances (2.38 Å) as a result of the
smaller metal radius.25 The C-Ga-C angle is tighter
(126.6°), and the sum of the angles around the sulfur is
322.1°. Although there is no directly relatable aluminum
complex, by examining a variety of aluminum-sulfur
dimeric complexes, one sees very similar overall geom-
etries, with a shortening of the expected bond distances
(metal-carbon and metal-sulfur).
Few structural studies have been reported for tert-
butyl derivatives of Al or Ga, but the structure of one,
[t-Bu2Al(µ-S-2,4,6-i-Pr3C6H2)]2, with bridging sulfur at-
oms, has appeared.26 In this system the (Al-S)2 ring is
planar, with the ligands in the anti arrangement. Other
structural parameters appear to be altered by the very
bulky groups on both the metal and the chalcogen.
Compound 6, [Me2In(µ-S-t-Bu)]3, is the second re-
ported example of an indium trimer, the first being [Me2-
In(µ-SSiPh3)]3.4 Both of these systems show the same
geometry, a skew-boat conformation, shown for 6 in
Figure 2. Selected bond distances and angles for 6 are
listed in Table 4. The In-C bond distances for 6 and
the C-In-C exocyclic angles are similar to those for
[Me2In(µ-SSiPh3)]3 and the other reported trimeric
group 13 derivatives listed in Table 5. Bond distances
and excocyclic C-M-C angles are also similar to those
reported for the dimers listed in Table 3. For compari-
son, the aluminum trimeric derivatives have been
included. The aluminum derivatives have been shown
to form either a skew-boat or chair conformation,
depending upon the substituents bound to the metal and
the ligand. More sterically demanding substituents on
F igu r e 2. Diagram of [Me2In(µ-S-t-Bu)]3 (6; 50% thermal
ellipsoids) showing the atom-labeling scheme. Hydrogen
atoms have been omitted for clarity.
Ta ble 4. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for [Me2In (µ-S-t-Bu )]3 (6) a n d
{t-Bu 2In [µ-S(4,6-Me2)C4N2H]}3 (7)
6
7
Bond Distances
2.563(4)
In(1)-S(1)
In(1)-S(3)
In(2)-S(2)
In(2)-S(1)
In(3)-S(3)
In(3)-S(2)
In(1)-C(1)
In(1)-C(2)
In(3)-C(6)
In(3)-C(5)
In(1)-S(1)#2
2.623(2)
2.712(2)
2.623(2)
2.576(4)
2.591(4)
2.595(3)
2.562(4)
2.584(3)
In(1)-S(1)
S(1)-In(1)#3
In(1)-C(7)#1
2.185(5)
2.185(5)
2.166(12) In(1)-C(7)
2.155(12)
2.137(12)
2.177(14) N(2)-In(1)#3
2.922(5)
2.922(5)
1.735(6)
In(1)-N(2)#2
S(1)-C(1)
S(1)-C(10)
S(2)-C(20)
S(3)-C(30)
1.86(2)
1.839(13)
1.869(13)
Bond Angles
C(2)-In(1)-C(1) 129.5(5)
C(4)-In(2)-C(3) 126.4(5)
C(6)-In(3)-C(5) 122.0(6)
C(7)#1-In(1)-C(7)
S(1)#2-In(1)-S(1)
In(1)#3-S(1)-In(1)
139.4(4)
79.78(7)
160.22(7)
C(7)#1-In(1)-N(2)#2 91.58(14)
C(7)-In(1)-N(2)#2 91.58(14)
S(1)-In(1)-S(3) 92.30(12) S(1)#2-In(1)-N(2)#2 55.39(9)
S(1)-In(1)-N(2)#2
C(1)-S(1)-In(1)#3
135.17(11)
94.9(2)
C(1)-S(1)-In(1)
104.9(2)
117.7(6)
126.4(6)
116.5(4)
117.1(5)
117.6(6)
93.3(3)
C(1)-N(1)-C(5)
N(2)-C(1)-N(1)
N(2)-C(1)-S(1)
N(1)-C(1)-S(1)
S(3)-In(3)-S(2) 96.89(11) C(1)-N(2)-C(2)
In(1)-S(1)-In(2) 110.12(13) C(1)-N(2)-In(1)#3
In(3)-S(2)-In(2) 109.39(12) C(2)-N(2)-In(1)#3
In(3)-S(3)-In(1) 114.08(12)
C(10)-S(1)-In(1) 107.1(6)
C(10)-S(1)-In(2) 108.0(5)
C(20)-S(2)-In(3) 106.6(5)
C(20)-S(2)-In(2) 106.7(5)
C(30)-S(3)-In(3) 109.7(5)
C(30)-S(3)-In(1) 107.2(5)
149.1(5)
the metal appear to favor the skew-boat conformation.
It was also shown that when the sum of the angles
around the sulfur approaches 360°, the conformation
becomes skew-boat. For the aluminum-thiolate trimer
systems, these angles ranged between 322.3 and 338.5°
for the chair conformations, and the sum of the angles
was 357.9° for the skew-boat conformation. The indium
systems do not follow this trend, since the sum of the
(24) Beachley, O. T., J r.; Chao, S.-H. L.; Churchill, M. R.; Lake, C.
H. Organometallics 1993, 12, 5025.
(25) Ghazi, S. U.; Kumar, R.; Heeg, M. J .; Oliver, J . P. Unpublished
results.
(26) Wehmschulte, R. J .; Ruhlandt-Senge, K.; Power, P. P. Inorg.
Chem. 1995, 34, 2593.

870 Organometallics, Vol. 19, No. 5, 2000
Yearwood et al.
Ta ble 5. Selected Bon d Dista n ces (Å) a n d An gles (d eg) Obser ved in [Me2In (µ-S-t-Bu )]3 (6),
{t-Bu 2In [µ-S(4,6-Me2)C4N2H]}3 (7), a n d Selected Gr ou p 13 Tr im er ic Der iva tives
av M-E
(Å)
E-M-E
(deg)
M-E-M
(deg)
sum of angles
around E (deg)
av M-C
(Å)
av C-M-C
compd
(deg)
[Me2In(µ-S-t-Bu)]3 (6)a
2.58
2.67
2.61
2.35
94.4
71.8
90.5
100.6
88.8
99.1
110.8
89.4
99.2
89.1
93.2
96.1
96.3
111.2
160.2
117.3
115.1
123.2
114.6
116.8
114.2
122.5
127.6
126.8
131.5
143.7
326.1
359.9
351.8
323.9
338.5
324.6
324.5
337.1
320.0
360.0
357.4
356.3
2.15
2.19
2.13
1.94
126.0
139.5
132.8
120.6
{t-Bu2In[µ-S(4,6-Me2)C4N2H]}3 (7)a
b
[Me2In(µ-SSiPh3)]3
c
{Me2Al[µ-S(2-t-BuC6H4)]}3
c
{Me2Al[µ-S(2-Me3Si)C6H4]}3
2.36
2.37
1.94
1.96
2.00
119.6
129.7
121.9
c
{i-Bu2Al[µ-S(2,4,6-i-Pr3C6H2)]}3
[t-Bu2Ga(µ-OH)]3 (planar)d
1.94
a
b
d
This work. Reference 4. c Reference 7. Naiini, A. A.; Young, V.; Han, Y.; Akinc, M.; Verkade, J . G. Inorg. Chem. 1993, 32, 3781.
F igu r e 3. Diagram showing the distances between the In
and N atoms in {t-Bu2In[µ-S(4,6-Me2)C4N2H]}3 (7).
F igu r e 5. Diagram of {Me2In[µ-S(2,6-Me2)C6H3]}4 (8; 50%
thermal ellipsoids) showing the atom-labeling scheme.
Hydrogen atoms have been omitted for clarity.
Ta ble 6. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for {Me2In [µ-S(2,6-Me2)C6H3]}4 (8)
bond distances
bond angles
In(1)-S(2)
2.584(2)
2.602(2)
2.581(2)
2.591(2)
S(2)-In(2)-S(1)
92.82(6)
90.03(6)
130.47(7)
123.33(7)
135.0(4)
131.2(4)
In(1)-S(1)#1
In(2)-S(2)
In(2)-S(1)
S(2)-In(1)-S(1)#1
In(2)-S(1)-In(1)#1
In(2)-S(2)-In(1)
C(17)-In(2)-C(18)
C(19)-In(1)-C(20)
In(1)-C(19)
In(1)-C(20)
In(2)-C(17)
In(2)-C(18)
S(1)-C(1)
2.159(8)
2.154(7)
2.135(7)
2.134(8)
1.788(6)
1.794(7)
C(1)-S(1)-In(2)
C(1)-S(1)-In(1)#1
105.0(2)
103.4(2)
S(2)-C(9)
C(9)-S(2)-In(2)
C(9)-S(2)-In(1)
104.0(2)
105.2(2)
rings. In the dimeric [Mes2In(µ-SSiPh3)]2 system, the
equivalent distances are 3.256 and 3.431 Å. If Me2InS-
t-Bu formed a dimeric species, these distances would
likely be shorter, but in the trimeric molecule 6, the
equivalent distances are 3.740 and 3.751 Å. This
provides further evidence that the substituents on the
metal and the chalcogen affect the degree of aggrega-
tion, an observation which has been commented upon
before with respect to the bulk of the groups bound to
the metal.8 The aggregate formed is dependent on the
fine balance between steric and electronic effects in
these systems, and small changes often lead to changes
in the observed structure.
F igu r e 4. Diagram showing the coordination around
indium in {t-Bu2In[µ-S(4,6-Me2)C4N2H]}3 (7).
angles around sulfur is 326.1° for 6 and 351.8° for [Me2-
In(µ-SSiPh3)]3 and both adopt the skew-boat conforma-
tion.
It was suggested previously that the small energy
changes associated with the shift from the dimeric to
the trimeric aggregation state may be due to interaction
between nonbonded atoms.4 In [Mes2In(µ-SSiPh3)]2, the
two shortest interatomic distances are 3.419 and 3.631
Å between a methyl carbon atom attached to the indium
atom and an ortho carbon atom of one of the phenyl

Organoindium Thiolate Oligomers
Organometallics, Vol. 19, No. 5, 2000 871
Ta ble 7. Selected Bon d Dista n ces (Å) a n d An gles (d eg) Obser ved in {Me2In [µ-S(2,6-Me2)C6H3]}4 (8) a n d
Oth er Tetr a m er ic Sp ecies
av M-E
(Å)
E-M-E
(deg)
M-E-M
(deg)
sum of angles
around S (deg)
av M-C
(Å)
av C-M-C
compd
(deg)
{Me2In[µ-S(2,6-Me2)C6H3]}4 (8)a
2.59
2.36
2.40
1.96
92.8
90.0
99.5
94.6
93.1
96.6
98.7
98.9
130.5
123.3
126.9
130.7
126.2
129.8
133.0
133.2
338.9
2.15
1.94
1.94
1.95
135.0
131.2
126.0
120.3
129.5
124.2
124.5
133.8
b
{Me2Al[µ-S(2,6-Me2C6H3)]}4
342.8
348.3
340.7
346.0
b
{Me2Ga[µ-S(2,6-Me2C6H3)]}4
c
[Me2Ga(µ-OH)]4
a
b
This work. Reference 7. c Smith, G. S.; Hoard, J . L. J . Am. Chem. Soc. 1959, 81, 3907.
these species, except for the bond distances, which are
dependent on the radii of the atoms involved.
The trimer 7, {t-Bu2In[µ-S(4,6-Me2)C4N2H]}3, differs
significantly from 6 and the other trimeric species
discussed above. The indium and pyrimidene ligands
lie in a plane with 3-fold symmetry. Only the tert-butyl
groups attached to the indium lie above and below this
plane. A diagram showing a portion of the molecule is
shown in Figure 3. The central ring is distorted sub-
stantially from a regular hexagon. The internal In-S-
In angles of 160.2° and S-In-S angles of 79.8° repre-
sent extremely large deviations from those that have
been reported previously, with the In-S-In angle
significantly larger, and the S-In-S angle significantly
smaller, than those seen in other group 13-chalcogen
trimers. The average In-S bond length is 2.67 Å, which
is within the range of previously reported bond dis-
tances, but the two individual In-S bond distances
differ with values of 2.712 and 2.623 Å. The In-C bond
lengths are in the normal range (Tables 3 and 5), but
the C-In-C angle is 139.5°, which is somewhat wider
than other reported values.
Figure 3 shows another unusual feature of this
molecule. The pyrimidene moiety is tipped toward one
In atom, giving rise to a very short In-N distance of
2.923 Å and a correspondingly long distance for the
other In-N separation of 3.362 Å. This unusual geom-
etry indicates an interaction between In and N which
leads to both the planar geometry and the distorted
structure. One can, in fact, consider that the indium
atoms have gone from the common four-coordinate
tetrahedral geometry to a distorted pentacoordinate
trigonal prism, as illustrated in Figure 4.
Con clu sion s
We have been able to demonstrate that it is possible
to extend current synthetic strategies used in the
preparation of group 13 chalcogenide derivatives to yield
new and unique systems. The dimers 2-5 show a planar
four-membered ring with the ligands in an anti ar-
rangement, and the trimer 6 crystallizes in the skew-
boat six-membered-ring configuration; however, the
trimer 7 forms a planar six-membered ring which
displays a unique geometry as a result of the secondary
interaction of the nitrogen atoms in the pyrimidene
moieties bound to the bridging sulfur atom. Compound
8 is the first reported tetramer for a diorganoindium
derivative.
We have also gathered more evidence supporting the
suggestion that steric interactions play an inportant role
in determining the C-M-C exocyclic angle and appear
to be the driving force in the determination of the
aggregation state for group 13-chalcogen complexes.
Further, we have shown that secondary interactions
which may occur when additional coordination sites are
present, either in the ligand bound to the metal or in
the bridging chalcogen, can substantially alter the
structure of these derivatives. Finally, there is some
evidence that it may be possible to control the In-S
bond length with careful selection of the organosulfur
moiety.
The indium tetramer 8 has a geometry very similar
to that of the aluminum and gallium tetramers {Me2-
Al[µ-S(2,6-Me2)C6H3]}4,7 {Me2Ga[µ-S(2,6-Me2)C6H3]}4,7
and [Me2Ga(µ-OH)]4,27 with each displaying an eight-
membered ring in an extended chair configuration as
shown in Figure 5. Selected bond distances and angles
are listed in Table 6. The average bond distances and
angles are well within the normal range for the dimers
and trimers listed in Tables 3 and 5. Of more interest
is the similarity of the four group 13 tetramers listed
in Table 7. There is little change in the geometry of
Ack n ow led gm en t is made to the donors of the
Petroleum Research Fund, administered by the Ameri-
can Chemical Society, for support of this research.
Su p p or tin g In for m a tion Ava ila ble: Thermal ellipsoid
diagrams for compounds 3-5 and 7 and complete listings of
bond distances and angles, atomic coordinates and isotropic
and anisotropic thermal parameters for the non-hydrogen
atoms, and atomic coordinates and isotropic thermal param-
eters for the hydrogen atoms for the four compounds. This
material is available free of charge via the Internet at
http://pubs.acs.org.
(27) Smith, G. S.; Hoard, J . L. J . Am. Chem. Soc. 1959, 81, 3907.
OM990887B