When arsine makes the difference: Chelating phosphino and bridging arsinoarylthiolato gallium complexes

Article abstract of DOI:10.1021/ic801582b

The (organo)gallium compounds GaCl{(SC₆H₄-2-PPh ₂)-κ²S,P}₂ (1), Ga{(SC₆H ₄-2-PPh₂)-K²S,P}{(SC₆H ₄-2-PPh₂)-κS}₂ (2), GaMe ₂{(SC₆H₄-PPh₂)-κ²S, P} (3), Ga^tBu₂{(SC₆H₄-2-PPh ₂)-κ²S,P} (4), Ga^tBu{(SC ₆H₄-2-PPh₂)-κ²S,P}{(SC ₆H₄-2-PPh₂)-κS} (5), [GaMe ₂{(μ₂-SC₆H₄-2-AsPh ₂)-κS}]₂ (6), and Ga^tBu{(SC ₆H₄-2-AsPh₂)-K²S,4s}{(SC ₆H₄-2-AsPh₂)-κS} (7) were obtained from the reaction of 2-EPh₂C₆H₄SH (E = P (PSH), As (AsSH)) with GaCl₃ (1,2) or GaR₃ (R = Me, ^tBu; 3-7) in different molar ratios and under different reaction conditions. Compound 2 was also obtained from Li(PS) and GaCl₃ (3.5:1). While a monomeric structure with a chelating phosphinoarylthiolato ligand is observed in GaMe₂{(SC₆H₄-₂-PPh ₂}-κ²S,P) (3), a dimeric arsinoarylthiolato-bridged complex [GaMe₂{(μ₂-SC₆H₄-2- AsPh₂)-κS}]₂ (6) is obtained with the corresponding AsS^- ligand. B3LYP/6-31G(d) calculations show that although the dimer is thermodynamically favored for both ligands, the formation of 3 is due to the combination of higher stability of the chelate compared with the monodentate phosphorus ligand and a higher barrier for the ring opening of the PS ^- than of the AsS^- chelate.

Full text of DOI:10.1021/ic801582b

Inorg. Chem. 2008, 47, 11284-11293
When Arsine Makes the Difference: Chelating Phosphino and Bridging
Arsinoarylthiolato Gallium Complexes
Ana Maria Va˘lean,†,‡ Santiago Go´mez-Ruiz,‡ Peter Lo¨nnecke,‡ Ioan Silaghi-Dumitrescu,†
Luminit¸a Silaghi-Dumitrescu,*,† and Evamarie Hey-Hawkins*,‡
Faculty of Chemistry and Chemical Engineering, “Babes¸-Bolyai” UniVersity, 1 Kogaˇlniceanu,
400084 Cluj-Napoca, Romania, and Institut fu¨r Anorganische Chemie der UniVersita¨t Leipzig,
Johannisallee 29, 04103 Leipzig, Germany
Received August 19, 2008
The (organo)gallium compounds GaCl{(SC6H4-2-PPh2)-κ2S,P}2 (1), Ga{(SC6H4-2-PPh2)-κ2S,P}{(SC6H4-2-PPh2)-κS}2
(2), GaMe2{(SC6H4-2-PPh2)-κ2S,P} (3), GatBu2{(SC6H4-2-PPh2)-κ2S,P} (4), GatBu{(SC6H4-2-PPh2)-κ2S,P}{(SC6H4-
2-PPh2)-κS} (5), [GaMe2{(µ2-SC6H4-2-AsPh2)-κS}]2 (6), and GatBu{(SC6H4-2-AsPh2)-κ2S,As}{(SC6H4-2-AsPh2)-κS}
(7) were obtained from the reaction of 2-EPh2C6H4SH (E ) P (PSH), As (AsSH)) with GaCl3 (1, 2) or GaR3 (R )
t
Me, Bu; 3-7) in different molar ratios and under different reaction conditions. Compound 2 was also obtained
from Li(PS) and GaCl3 (3.5:1). While a monomeric structure with a chelating phosphinoarylthiolato ligand is observed
in GaMe2{(SC6H4-2-PPh2)-κ2S,P} (3), a dimeric arsinoarylthiolato-bridged complex [GaMe2{(µ2-SC6H4-2-AsPh2)-
κS}]2 (6) is obtained with the corresponding AsS- ligand. B3LYP/6-31G(d) calculations show that although the
dimer is thermodynamically favored for both ligands, the formation of 3 is due to the combination of higher stability
of the chelate compared with the monodentate phosphorus ligand and a higher barrier for the ring opening of the
PS- than of the AsS- chelate.
Introduction
microelectronic devices,3 or for medical purposes4,5 but also
due to their structural variety.6 Thus, the number of group
13 metal compounds with tertiary phosphines and arsines7,12
is continuously growing and is related to both aspects, their
applications and their very interesting and rewarding chemistry.
Mixed group 13/15 (Ga, In/P, As) compounds have been
under investigation for many years not only due to their wide
applications in materials science,1,2 for fabrication of various
* To whom correspondence should be addressed. E-mail: lusi@
chem.ubbcluj.ro (L.S.-D.), hey@uni-leipzig.de (E.H.-H.). Fax: 40-264-
590818 (L.S.-D.), +49(0)-341-9739319 (E.H.-H.); Tel: 40-264-593833(L.S.-
D.), +49(0)-341-9736151(E.H.-H.).
(3) (a) Salzman, D. B.; Yulius, A.; Chen, A.; Woodall, J. M.; Harmon,
E. U.S. Patent 20060145190, 2006, 24 pp. (b) Koyama, R. Y. In
Handbook of Compound Semiconductors; Holloway, P. H., McGuire,
G. E., Eds.; William Andrew Publishing/Noyes: Park Ridge, NJ,
1995,Chapter 15, pp 772-812. (c) Kanber, H. U.S. Patent 5,312,765,
1994, 9pp. (d) Hersee, S. D.; Yang, L.; Kao, M.; Martin, P.;
Mazurowski, J.; Chin, A.; Ballingall, J. J. Cryst. Growth 1992, 120,
218–227. (e) Pellegrino, S.; Tarricone, L. Mater. Chem. Phys. 2000,
66, 189–196. (f) Scavennec, A. J. Phys. Colloques 1988, 49, 115–
123. (g) Ivanov, S. V.; Kop’ev, P. S. In Optoelectronic Properties of
Semiconductors and Superlattices; Manasreh, M. O., Ed.; Gordon &
Breach Science Publishers: Amsterdam, 1997, Vol 3, pp 95-170. (h)
Petrov, V. N.; Tsyrlin, G. E.; Golubok, A. O.; Komyak, N. I.; Ustinov,
V. M.; Ledentsov, N. N.; Alferov, Z. I.; Bimberg, D. Russ. Micro-
electron. 2001, 30, 99–105.
(4) (a) Britigan, B. E.; Singh, P. World Patent WO2005055723, 2005, 46
pp. (b) Perl, D. P.; Moalem, S. World Patent WO2007053581, 2007,
32 pp.
(5) (a) Jakupec, M. A.; Keppler, B. K. In Metal Ions in Biological Systems;
Siegel, A.; Siegel, H., Eds.; Dekker: New York, 2004; Vol 42, pp
425-462. (b) Frezza, M.; Verani, C. N.; Chen, D.; Dou, Q. P. Lett.
Drug Des. DiscoVery 2007, 4, 311–317. (c) Rudnev, A. V.; Foteeva,
L. S.; Kowol, C.; Berger, R.; Jakupec, M. A.; Arion, V. B.; Timerbaev,
A. R.; Keppler, B. K. J. Inorg. Biochem. 2006, 100, 1819–1826.
†
“Babes¸-Bolyai” University.
‡
Universita¨t Leipzig.
(1) (a) Katz, A. Indium Phosphide and Related Materials: Processing,
Technology, and DeVices; Artech House Publishers: Norwood, MA,
1992. (b) Howes, M. J.; Morgan, D. V. Gallium Arsenide: Materials,
DeVices, and Circuits; John Wiley & Sons: New York, 1985. (c)
Winnacker, A. Phys. Bl. 1990, 46, 185–187. (d) Beneking, H. J.
Electrochem. Soc. 1989, 136, 2680–2686. (e) Hjort, K.; So¨derkvist,
J.; Schweitz, J. A. J. Micromech. Microeng. 1994, 4, 1–13. (f) Markov,
A. V.; Mezhennyi, M. V.; Polyakov, A. Y.; Smirnov, N. B.; Govorkov,
A. V.; Eremin, V. K.; Verbitskaya, E. M.; Gavrin, V. N.; Kozlova,
Y. P.; Veretenkin, Y. P.; Bowles, T. J. Nucl. Instrum. Methods Phys.
Res., Sect. A 2001, 466, 14–24. (g) Owens, A.; Bazdaz, M.; Kraft, S.;
Peacock, A.; Nenonen, S.; Andersson, H. Nucl. Instrum. Methods Phys.
Res., Sect. A 2000, 442, 360–363.
(2) (a) Grant, I. R. In Chemistry of Aluminium, Gallium, Indium and
Thallium; Downs, A. J., Ed.; Blackie; London, 1993; Chapter 5, pp
292-321. (b) Blakemore, J. S. J. Appl. Phys. 1982, 53, R123–R181.
(c) Bosi, M.; Pelosi, C. Prog. PhotoVoltaics: Res. Appl. 2007, 15,
51–68.
11284 Inorganic Chemistry, Vol. 47, No. 23, 2008
10.1021/ic801582b CCC: $40.75  2008 American Chemical Society
Published on Web 11/06/2008

When Arsine Makes the Difference
More complex systems where group 13/15 components
are accompanied by other elements such as oxygen or sulfur
are barely studied.13 Phosphinoarylthiols and arsinoarylthiols
are excellent heteropolytopic ligands, and the combination
of phosphorus or arsenic with the multiple coordination
patterns offered by the presence of sulfur leads to a great
variety of structures. While transition metal complexes of
2-PPh2C6H4SH have been reported previously14 derivatives
of main group metals, including group 13 elements, are
almost unexplored as only some tin15 and indium16 com-
plexes have been reported so far. The coordination chemistry
of 2-AsPh2C6H4SH is even less explored, the preparation of
the free ligand being only recently reported.17 Here, we report
on the synthesis and characterization of the gallium and
organogallium complexes GaCl{(SC6H4-2-PPh2)-κ2S,P}2 (1),
Ga{(SC6H4-2-PPh2)-κ2S,P}{(SC6H4-2-PPh2)-κS}2 (2), GaMe2-
{(SC6H4-2-PPh2)-κ2S,P} (3), GatBu2{(SC6H4-2-PPh2)-κ2S,P}
(4), GatBu{(SC6H4-2-PPh2)-κ2S,P}{(SC6H4-2-PPh2)-κS} (5),
[GaMe2{(µ2-SC6H4-2-AsPh2)-κS}]2 (6), and GatBu{(SC6H4-
2-AsPh2)-κ2S,As}{(SC6H4-2-AsPh2)-κS} (7).
Experimental Section
General Procedures. All manipulations were carried out under
an inert atmosphere of dry nitrogen. Cyclohexane, n-hexane,
toluene, diethyl ether, and THF were dried over sodium/benzophe-
none, distilled under an atmosphere of dry argon, and stored over
a potassium mirror. CH2Cl2, MeOH, and tetramethylethylenedi-
amine (TMEDA) were refluxed over CaH2, distilled, and kept under
nitrogen. Some deuterated solvents needed for NMR spectroscopy
were used as purchased and kept under inert atmosphere over
potassium mirror (C7D8) or molecular sieves (THF-d8). C6D6 was
dried with sodium/potassium alloy, filtered, and kept under inert
atmosphere over potassium mirror. CDCl3 was dried over LiAlH4,
distilled, and kept over molecular sieves. nBuLi (2.2 M in n-hexane),
tBuLi (1.47 M in n-pentane), NEt3, GaCl3, and GaMe3 were obtained
from commercial suppliers. GaCl3 was freshly sublimed before use.
GatBu3 was synthesized by minor modifications of the standard
literature procedure involving the reaction of GaCl3 with tBuLi (1:
3).18,19 The ligands 2-EPh2C6H4 SH (E ) P (PSH), As (AsSH))
were prepared from thiophenol by ortho-lithiation/electrophilic
substitution,17,20 using Schlenk techniques and dry solvents.
Elemental analysis was performed with a Vario EL-Heraeus
microanalyzer. IR spectra were recorded using a Perkin-Elmer
System 2000 spectrometer in the range 4000-400 cm-1 and
400-200 cm-1 using KBr and CsI pellets, respectively. H and
1
31P NMR spectra were recorded on a Bruker Avance DRX-400
instrument, 1H NMR using TMS as internal standard and 31P NMR
using external 85% H3PO4.
(6) (a) Wells, R. L.; Purdy, A. P.; McPhail, A. T.; Pitt, C. G. J. Chem.
Soc., Chem. Commun. 1986, 487–488. (b) Purdy, A. P.; Wells, R. L.;
McPhail, A. T.; Pitt, C. G. Organometallics 1987, 6, 2099–2105. (c)
Petrie, M. A.; Power, P. P. Inorg. Chem. 1993, 32, 1309–1312. (d)
Culp, R. D.; Cowley, A. H.; Decken, A.; Jones, R. A.; Bond, M. R.;
Mokry, L. M.; Carrano, C. J. Inorg. Chem. 1997, 36, 5165–5172. (e)
Bauer, T.; Schulz, S.; Nieger, M.; Kessler, U. Organometallics 2003,
22, 3134–3142. (f) Hoffmann, C. G.; Fischer, R.; Schubert, U.; Hirle,
B. J. Organomet. Chem. 1992, 441, 7–14. (g) Steiner, J.; Sto¨sser, G.;
Schno¨ckel, H. Angew. Chem., Int. Ed. 2004, 43, 302–305. (h) Baker,
R. J.; Bettentrup, H.; Jones, C. Eur. J. Inorg. Chem. 2003, 2446–
2451. (i) Lee, J. D.; Ko, J.; Cheong, M.; Kang, S. O. Organometallics
2005, 24, 5845–5852. (j) Hibbs, D. E.; Jones, C.; Smithies, N. A.
Chem. Commun. 1999, 2, 185–186. (k) Robinson, G. H. In Compre-
hensiVe Coordination Chemistry II; McCleverty, J. A., Meyer, T. J.,
Eds.; Elsevier: Oxford, U.K., 2004; Vol 3, pp 347-382.
(7) Bradley, D. C.; Chudzynska, H.; Faktor, M. M.; Frigo, D. M.;
Hursthouse, M. B.; Hussain, B.; Smith, L. M. Polyhedron 1988, 7,
1289–1298.
(8) Wells, R. L.; Aubuchon, S. R.; Self, M. F.; Jasinski, J. P.; Woudenberg,
R. C.; Butcher, R. J. Organometallics 1992, 11, 3370–3375.
(9) Baker, L. J.; Rickard, C. E. F.; Taylor, M. J. J. Organomet. Chem.
1994, 464, C4–C6.
The mass spectra were recorded on a VG12-520 mass spectro-
meter (EI-MS, 70 eV, 200 °C), FT ICR MS Bruker Daltonics ESI
mass spectrometer (APEX II, 7 T), or a MASPEC II spectrometer
(FAB MS, matrix ) 3-nitrobenzylalcohol).
The crystallographic data were collected on a Siemens CCD
diffractometer (SMART) with ω scan rotation, data reduction with
SAINT,21 and empirical absorption correction with SADABS22
(compounds 2, 4, 7) and on a CCD Oxford Xcalibur S diffracto-
meter in ω- and ꢀ-scan mode with data reduction with CrysAlisPro
including empirical absorption correction with SCALE3 AB-
SPACK23 (compounds 1, 3, 5, 6). Radiation was Mo KR (λ )
0.71073 Å). Structure refinement was carried out with SHELXL-
97.24 Non-hydrogen atoms, except poorly defined disordered
regions, were refined anisotropically, and H atoms were calculated
on idealized positions. Structure figures were generated with
ORTEP.25 Thermal ellipsoids are drawn at 50% probability if not
otherwise mentioned. The relevant crystallographic data and
refinement details are shown in Table 1. For complex 5, a
temperature of 220(2) K was used, because the crystals cracked at
lower temperatures. CCDC 688529 (1), 688530 (2), 688531 (3),
(10) (a) Briand, G. G.; Davidson, R. J.; Decken, A. Inorg. Chem. 2005,
44, 9914–9920. (b) Wells, R. L.; Aubuchon, S. R.; Kher, S. S.; Lube,
M. S.; White, P. S. Chem. Mater. 1995, 7, 793–800.
(11) Cheng, F.; Codgbrook, H. L.; Hector, A. L.; Levason, W.; Reid, G.;
Webster, M.; Zhang, W. Polyhedron 2007, 26, 4147–4155.
(12) (a) Wells, R. L.; Foos, E. E.; Rheingold, A. L.; Yap, G. P. A.; Liable-
Sands, L. M.; White, P. S. Organometallics 1998, 17, 2869–2875.
(b) Cooke, J. A. L.; Rahbarnoohi, H.; McPhail, A. T.; Wells, R. L.;
White, P. S. Polyhedron 1996, 15, 3033–3044.
(18) Higa, K. T.; George, C. Organometallics 1990, 9, 275–277.
(19) Kovar, R. A.; Derr, H.; Brandau, D.; Callaway, J. O. Inorg. Chem.
1975, 14, 2809–2814.
(20) (a) Block, E.; Ofori-Okai, G.; Zubieta, J. J. Am. Chem. Soc. 1989,
111, 2327–2329. (b) Pe´rez-Lourido, P.; Garc´ıa-Va´zquez, J. A.;
Romero, J.; Sousa, A.; Block, E.; Maresca, K. P.; Zubieta, J Inorg.
Chem. 1999, 38, 538–544.
(13) Saatchi, K.; Patrick, B. O.; Orvig, C. Dalton Trans. 2005, 2268–2274.
(14) (a) Dilworth, J. R.; Wheatley, N. Coord. Chem. ReV. 2000, 199, 89–
158. (b) Cabeza, J. A.; Mart´ınez-Garc´ıa, M. A.; Riera, V.; Ardura,
D.; Garc´ıa-Granda, S. Eur. J. Inorg. Chem. 2000, 499–503. (c) Real,
´
´
J.; Prat, E.; Polo, A.; Alvarez-Larena, A.; Piniella, J. F. Inorg. Chem.
Commun. 2000, 3, 221–223.
(21) SAINT: Area-Detector Integration Software, Version 6.01, Siemens
Industrial Automation, Inc., Madison, WI, 1999.
(15) (a) Ferna´ndez, E. J.; Hursthouse, M. B.; Laguna, M.; Terroba, R. J.
Organomet. Chem. 1999, 574, 207–212. (b) Pe´rez-Lourido, P.;
Romero, J.; Garc´ıa-Va´zquez, J. A.; Sousa, A.; Zubieta, J.; Russo, U.
J. Organomet. Chem. 2000, 595, 59–65. (c) Canseco-Gonza´lez, D.;
Go´mez-Ben´ıtez, V.; Herna´ndez-Ortega, S.; Toscano, R. A.; Morales-
Morales, D. J. Organomet. Chem. 2003, 679, 101–109.
(16) Pe´rez-Lourido, P.; Romero, J.; Garc´ıa-Va´zquez, J. A.; Sousa, A.;
Maresca, K.; Zubieta, J. Inorg. Chem. 1999, 38, 1293–1298.
(17) (a) Hildebrand, A. Ph.D. thesis, “Babes¸-Bolyai” University and
Universita¨t Leipzig, 2006. (b) Hildebrand, A.; Lo¨nnecke, P.; Silaghi-
Dumitrescu, L.; Hey-Hawkins, E. Dalton Trans. 2008, 4639–4646.
(22) Sheldrick, G. M. SADABS, Program for Scaling and Correction of
Area-detector Data, University of Go¨ttingen, Germany, 1997.
(23) CrysAlisPro software, Oxford Diffraction Ltd., Abingdon, Oxfordshire,
England, including empirical absorption correction using spherical
harmonics, implemented in SCALE3 ABSPACK scaling algorithm.
(24) Sheldrick, G. M. SHELXL-97, Program for the Refinement of Crystal
Structures, University of Go¨ttingen, Go¨ttingen, Germany, 1997.
(25) (a) Johnson, C. K., ORTEP, Report ORNL-5138, Oak Ridge National
Laboratory, Oak Ridge, TN, 1976. (b) Farrugia, L. J. J. Appl.
Crystallogr. 1997, 30, 565–565.
Inorganic Chemistry, Vol. 47, No. 23, 2008 11285

Va˘lean et al.
11286 Inorganic Chemistry, Vol. 47, No. 23, 2008

When Arsine Makes the Difference
688532 (4), 688533 (5), 688534 (6), and 688535 (7) contain the
supplementary crystallographic data for this paper. The data can
be obtained free of charge via www.ccdc.cam.ac.uk/conts/retriev-
ing.html (or from the Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB2 1EZ, UK; fax (+44)1223-336-033
or e-mail deposit@ccdc.cam.uk).
B3LYP/6-31G(d) full-geometry optimizations were performed
on model systems in which both phenyl substituents on phosphorus
or arsenic were replaced by hydrogen atoms by using the Spartan
06 package of programs.26
744vs, 697vs, 535w, 519m, 502vs, 471m, and 456w. νmax(CsI)/
cm-1: 390s (Ga-Sas.), 371w, 336m (Ga-S), 324m, 300s, 260m,
236m, and 215w. δH (400 MHz, CDCl3): 7.08-7.41 (33H, m, aryl-
H), 6.97 (3H, t, aryl-H), 6.90 (3H, t, aryl-H), and 6.64 (3H, d, aryl-
H). δP (161.9 MHz, CDCl3): -12.6 (dynamic in solution). m/z (EI):
655.1 (100%, M+ - C18H14PS) and 293.1 (80%, C18H14PS+).
Synthesis of GaMe2{(SC6H4-2-PPh2)-K2S,P} (3). Trimethyl-
gallium (0.445 g, 3.87 mmol, 2.55 mL, 1.52 M in n-hexane) was
added dropwise to a stirred slurry of PSH (1.14 g, 3.87 mmol) in
n-hexane (25 mL) at -78 °C (ca. 15 min). During the addition of
trimethylgallium, vigorous evolution of gas was observed. The
reaction mixture was stirred for a further 3 h, and a white precipitate
was formed. The precipitate was isolated by filtration, washed with
n-hexane and dried in Vacuo (yield 1.31 g, 3.33 mmol, 86%).
Compound 3 could be isolated as the only product even in a 1:1
reaction of 2 with GaMe3 (yield 96% based on 2). Colorless crystals
of 3 suitable for X-ray studies were obtained from diethyl ether at
room temperature (mp 180-188 °C). Elemental analysis: found
C, 60.89; H, 5.02%; calcd for C20H20GaPS (M ) 393.11) C, 61.10;
H, 5.13%. νmax(KBr)/cm-1: 3057w, 2963w, 1573s, 1480m, 1436vs,
1423s, 1248m, 1181w, 1126m, 1100vs, 1046m, 1026m, 998m,
801w, 754vs, 747vs, 722m, 695vs, 580m, 545w, 530m, 518s, 504s,
and 470s. νmax(CsI)/cm-1: 382s (Ga-S), 292m, 264m, 249w, 229w,
223w, and 209w. δH (400 MHz, C6D6): 7.84 (1H, t, aryl-H), 7.28
(1H, t, aryl-H), 6.96 (1H, d, aryl-H), 6.86-6.93 (10H, m, aryl-H),
6.64 (1H, t, aryl-H), and 0.26 (6H, s, CH3). δP (161.9 MHz, C6D6):
-1.2. m/z (FAB): 393.0 (100%, M+ + 1) and 293.1 (36%,
C18H14PS+).
Synthesis of GatBu2{(SC6H4-2-PPh2)-K2S,P} (4). A slurry of
PSH (0.43 g, 1.45 mmol) in n-hexane (10 mL) was cooled to -78
°C, and GatBu3 (0.35 g, 1.45 mmol) was added dropwise. After
addition was complete, the reaction mixture was warmed to room
temperature and refluxed for 1 h. The volatiles were removed in
Vacuo, and the resulting complex was obtained as a white precipitate
(yield 0.65 g, 1.36 mmol, 94%). Colorless crystals of 4 were
obtained after crystallization from n-hexane solution at 8 °C (mp
132-138 °C). Elemental analysis: found C, 64.01; H, 6.48; S,
6.58%; calcd for C26H32GaPS (M ) 477.27) C, 65.43; H, 6.76; S,
6.72%. νmax(KBr)/cm-1: 3059w, 2928s, 2947s, 2915s, 2866m,
2837vs, 1571m, 1481m, 1465m, 1438s, 1423s, 1359w, 1263m,
1247w, 1159w, 1098s, 1046m, 1027m, 943vw, 866vw, 809m,
747vs, 741vs, 719w, 694s, 533w, 505m, 474m, and 442w. νmax(CsI)/
cm-1: 377s (Ga-S), 297s, 280s, 265m, 248m, 233w, 215m, and
208s. δH (400 MHz, C6D6): 7.88 (1H, t, aryl-H), 7.49 (1H, t, aryl-
H), 6.89-6.97 (11H, m, aryl-H), 6.61 (1H, t, aryl-H), and 1.25
(18H, s, C(CH3)3). δP (161.9 MHz, C6D6): 0.4. m/z (EI): 419.0
(100%, M+ - C4H8), 363.0 (27%, M+ - C8H17), and 293.1 (12%,
C18H14PS+).
Synthesis of GaCl{(SC6H4-2-PPh2)-K2S,P}2 (1). A solution of
PSH (0.63 g, 2.14 mmol) and triethylamine (NEt3, 0.216 g, 2.14
mmol, 0.3 mL) in methanol (20 mL) was slowly added dropwise
to a solution of freshly sublimed GaCl3 (0.38 g, 2.15 mmol) in 10
mL of methanol. A white precipitate formed immediately. The
reaction mixture was stirred at room temperature for 1 h, and then
the white precipitate was separated by filtration, washed with
methanol, and dried in Vacuo. The main product was GaCl{(SC6H4-
2-PPh2)-κ2S,P}2 (0.72 g, 1.03 mmol, 96% based on PSH) but a
small amount of 2 was also obtained. A 0.5:1 molar ratio (PSH/
GaCl3) also led to compound 1 (mp 230-234 °C) as the major
product, whereas a mixture of 1 and 2 was obtained from the 2:1
reaction. Colorless crystals of 1 were obtained either from dichlo-
romethane solution at 8 °C or from THF/n-hexane at room
temperature. Both types of crystals were suitable for X-ray
measurement, but only the X-ray data of the crystals obtained from
THF/n-hexane are discussed. Elemental analysis: found C, 59.65;
H, 4.08; S, 8.68%; calcd for C36H28ClGaP2S2 · 1/2CH2Cl2 (M )
734.28) C, 59.70; H, 3.98; S, 8.73%. νmax(KBr)/cm-1: 3052w,
1572m, 1551w, 1481m, 1436s, 1424s, 1308w, 1250s, 1185w,
1130w, 1099s, 1044m, 1027m, 999m, 806w, 744vs, 694vs, 530w,
515m, 503m, 469m, and 400s (Ga-Sas). νmax(CsI)/cm-1: 337s
(Ga-Cl and Ga-S), 309m, 267m, 238m, and 219w. δH (400 MHz,
CDCl3): 7.58-7.25 (24H, m, aryl-H), 7.05 (2H, t, aryl-H) and 6.94
(2H, t, aryl-H). δP (161.9 MHz, CDCl3): -17.5. m/z (69Ga) (ESI,
in CH2Cl2) 691.0 (M++1). m/z (EI) 293.1 (100%, C18H14PS+).
Synthesis of Ga{(SC6H4-2-PPh2)-K2S,P}{(SC6H4-2-PPh2)-KS}2
(2). In method a, a solution of PSH (1.45 g, 4.92 mmol) and
triethylamine (0.49 g, 4.92 mmol, 0.68 mL) in methanol (40 mL)
was added dropwise to a stirred solution of GaCl3 (0.29 g, 1.64
mmol) in 10 mL of methanol at room temperature (ca. 10 min).
Immediately, a white precipitate formed. The reaction mixture was
stirred overnight. The white precipitate was isolated by filtration
and dried in Vacuo. Yield of 2: 1.31 g, 1.38 mmol, 84%. Mp
239-243 °C. A small amount of compound 1 was also obtained.
n
In method b, Li(PS) was prepared by treating PSH with BuLi
(1:1). A solution of GaCl3 (0.14 g, 0.8 mmol) in toluene (8 mL)
was added slowly dropwise to the slurry of Li(PS) (0.84 g, 2.8
mmol) in toluene (20 mL) with continuous stirring. A turbid solution
was obtained, which was stirred at room temperature for 40 h. The
lithium chloride formed was removed by filtration, and the volatiles
were removed in Vacuo to give compound 2 as a white solid (0.72
g, 0.76 mmol, 95% based on Li(PS)) and a small amount of
compound 1. Colorless crystals of 2 were obtained either from
diethyl ether or from tetrahydrofuran solution on cooling at 8 °C.
Both types of crystals were measured by X-ray diffraction, but only
the data of those obtained from diethyl ether are presented in this
paper. Elemental analysis: found C, 67.64; H, 4.71; calcd for
Synthesis of GatBu{(SC6H4-2-PPh2)-K2S,P}{(SC6H4-2-PPh2)-
KS} (5). Complex 5 was obtained as a minor product from the 1:2
reaction of GatBu3 (0.20 g, 0.83 mmol) with PSH (0.48 g, 1.65
mmol). Treatment of an n-hexane solution of the ligand at -78 °C
with GatBu3 followed by refluxing for 19 h gave a mixture of 4
(ca. 25%), 5 (ca. 20%), 2 (ca. 1%), and unconsumed ligand (ca.
50%), as well as some decomposition products. The products could
be separated by crystallization. Slow crystallization from n-hexane
at room temperature over 3 months afforded a few colorless crystals
of 5 (mp 235-239 °C). Elemental analysis: found C, 67.15; H,
5.14; S, 9.04%; calcd for C40H37GaP2S2 (M ) 713.48) C, 67.33;
H, 5.23; S, 8.99%. νmax(KBr)/cm-1: 3046m, 2912m, 2836m, 1570m,
1480m, 1434s, 1423s, 1305w, 1261w, 1250m, 1096s, 1040m,
1027s, 998w, 811m, 740vs, 694vs, 529w, 502s, and 471m.
C54H42GaP3S3 (M ) 949.69) C, 68.29; H, 4.46%. νmax(KBr)/cm-1
:
3052s, 3039m, 1585w, 1570m, 1553w, 1478s, 1435vs, 1422vs,
1332w, 1251m, 1156m, 1101s, 1039s, 1027m, 998w, 864w, 803w,
(26) SPARTAN ’06, Wavefunction Inc., W.I., 18401 Von Karman Avenue,
Suite 370 Irvine, CA 92612.
ν
max(CsI)/cm-1: 385w (Ga-S), 319w, 285w, 280s, 268m, 249m,
Inorganic Chemistry, Vol. 47, No. 23, 2008 11287

Va˘lean et al.
Scheme 1. The Synthetic Routes to 1-7
243w, 225m, 212m, and 203s. δH (400 MHz, C6D6): 6.69-7.59
(28H, m, aryl-H), and 1.30 (9H, s, C(CH3)3). δP (161.9 MHz, C6D6):
-9.6. m/z (EI): 655.0 (3%, M+ - C4H8) and 293.2 (37%,
C18H14PS+).
Results and Discussion
The reactivity and the coordination chemistry of the
bidentate ligands 2-EPh2C6H4SH (E ) P (PSH), As (AsSH))
toward gallium(III) and the influence of different substituents
at gallium on these reactions were studied. Seven new
gallium and organogallium complexes (Ga(ES)nX3-n, (1-7),
n ) 1-3, Scheme 1) were obtained by reaction of the ligands
or their lithium salts with GaX3 (X ) Cl, Me, tBu) in different
molar ratios and under different reaction conditions.
Synthesis of [GaMe2{(µ2-SC6H4-2-AsPh2)-KS}]2 (6). Trimeth-
ylgallium (0.088 g, 0.77 mmol, 0.50 mL, 1.52 M in n-hexane) was
added to a stirred solution of AsSH (0.26 g, 0.77 mmol) in toluene
(12 mL) at -78 °C. During the addition of trimethylgallium,
vigorous evolution of gas was observed. The reaction mixture was
stirred at room temperature overnight. The volatiles were removed
in Vacuo to give a white powder (yield 0.31 g, 0.71 mmol, 92%).
Colorless crystals of 6 suitable for X-ray studies were obtained
from a diethyl ether solution at room temperature in a few hours
(mp 157-165 °C). Elemental analysis: found C, 54.58; H, 4.20%;
calcd for C40H40As2Ga2S2 (M ) 874.12) C, 54.96; H, 4.61%.
Complexes 1-7 were obtained in good yields as white
solids (except 5 and 7, see below) and were fully character-
1
ized by H and 31P NMR spectroscopy, IR, mass spectro-
metry, elemental analysis, and X-ray diffraction.
1
max(KBr)/cm-1: 3047m, 2964m, 2905w, 1571w, 1480w, 1434s,
The H NMR spectra for all complexes show the signals
ν
due to the aromatic rings and no signal for the S-H proton.
The 1H NMR spectra of 3-7 show additional signals in the
aliphatic region due to the corresponding protons of the alkyl
groups (methyl or tert-butyl) with integrals for the aliphatic
and aromatic resonances in the ratio consistent with the
presence of one or two alkyl groups per PS- or AsS- ligand.
1306m, 1260s, 1186m, 1098s, 1025s, 947w, 866w, 803m, 739vs,
696s, 591w, 537w, 473m, and 446w. νmax(CsI)/cm-1: 321w, 303s
(Ga-S), 283w, 273w, 253m, 248m, 239w, 227w, and 203m. δH
(400 MHz, C6D6): 7.66 (2H, d, aryl-H), 7.30 (2H, d, aryl-H), 7.01
(20H, m, aryl-H), 6.89 (2H, t, aryl-H), 6.73 (2H, t, aryl-H) and
0.27 (12H, s, CH3). m/z (FAB): 437.0 (18%, M/2+ + 1), 421.0
(34%, M/2+ - CH2), and 337.1 (100%, C18H14AsS+).
Synthesis of GatBu{(SC6H4-2-AsPh2)-K2S,As}{(SC6H4-2-AsPh2)-
KS} (7). An n-hexane solution of GatBu3 (0.61 g, 2.53 mmol) was
added to AsSH (0.85 g, 2.53 mmol) in n-hexane at -78 °C.
Evolution of gas was noted upon addition. The colorless solution
was stirred for 24 h, the volatiles were removed in Vacuo, and the
oily white residue was washed with small amounts of n-hexane,
leaving a white powder. A few crystals of compound 7 were
obtained from n-hexane at room temperature over 2 days. However,
the 1H NMR spectrum showed two sets of signals for the aromatic
and aliphatic protons indicating that complex 7 was obtained in a
mixture, probably together with GatBu2{(SC6H4-2-AsPh2)-κ2S,As}.
Attempts to separate the compounds were unsuccessful.
27
The absence of νS-H and the presence of νGa-S at
400-300 cm-1 in the IR spectra of 1-6 indicate coordination
of the deprotonated thiolato ligands. The assignment of νGa-C
in the IR spectra of complexes 3-6 is complicated by the
number of bands in the expected range of 390-510 cm-1.28
(27) Hoffmann, G. G. Chem. Ber. 1983, 116, 3858–3866.
(28) (a) Uhl, W.; Spies, T.; Saak, W. Z. Anorg. Allg. Chem. 1999, 625,
2095–2109. (b) Uhl, W.; Cuypers, L.; Harms, K.; Kaim, W.; Wanner,
M.; Winter, R.; Koch, R.; Saak, W. Angew. Chem., Int. Ed. 2001, 40,
566–568. (c) Uhl, W.; Breher, F.; Haddadpour, S.; Koch, R.; Matar,
M. Z. Anorg. Allg. Chem. 2004, 630, 1839–1845. (d) Uhl, W.; Fick,
A. C.; Spies, T.; Geiseler, G.; Harms, K. Organometallics 2004, 23,
72–75.
11288 Inorganic Chemistry, Vol. 47, No. 23, 2008

When Arsine Makes the Difference
By comparison with other GaCl-containing compounds29-31
and the calculated normal modes,32 the band at 337 cm-1 in
the IR spectrum of complex 1 is assigned to νGa-Cl
.
The molecular-ion peaks were visible in the ESI MS
spectrum of 1 and 3 and in the FAB MS spectrum of 6. The
peaks corresponding to the loss of one molecule of ligand
are present in the EI MS spectra of 2 and 5, while the loss
of the organic groups attached to gallium was observed in
the spectra of 4, 5, and 6.
From the reaction of PSH with GaCl3 in the presence of
NEt3 in both 0.5:1 or 1:1 molar ratio GaCl{(SC6H4-2-PPh2)-
κ2S,P}2 (1) was obtained (Scheme 1). No GaCl2(PS) was
observed irrespective of the molar ratio used. The reaction
of PSH with GaCl3 in the molar ratio 3:1 led to Ga{(SC6H4-
2-PPh2)-κ2S,P}{(SC6H4-2-PPh2)-κS}2 (2). Compound 2 could
be also synthesized in higher yield by treating the lithium
salt of the ligand Li(PS) with GaCl3 in a 3.5:1 molar ratio.
Li(PS) was prepared from PSH and nBuLi in toluene (Scheme
1). In the solid state, compounds 1 and 2 are air-stable for
at least 2 days.
The 31P NMR spectrum of complex 1 shows one signal at
-17.5 ppm, which is shifted to high field relative to the free
ligand (-12.6 ppm), indicating the coordination of the
phosphorus atoms. Both, the room-temperature and the low-
temperature (173 K, THF-d8) 31P NMR spectra of 2 exhibit
signals in the range of the free ligand, suggesting noncoor-
dinating phosphine groups in solution.
The organogallium complexes GaMe2{(SC6H4-2-PPh2)-
κ2S,P} (3) and GatBu2{(SC6H4-2-PPh2)-κ2S,P} (4) were
obtained by reaction of PSH with GaMe3 and GatBu3 (ratio
1:1), respectively (Scheme 1). Compound 3 was also obtained
in excellent yield (96%) from 2 and GaMe3 in toluene at
room temperature. Compound 3 is an air-stable compound
that sublimes at 200 °C (under dynamic vacuum, 3 × 10-3
mbar) giving colorless crystals. In the 31P NMR spectra of
compounds 3 and 4, only one signal at -1.2 (3) and 0.4
ppm (4), respectively, is observed, consistent with the
coordination of the phosphine group.
Figure 1. Molecular structure of GaCl{(SC6H4-2-PPh2)-κ2S,P}2 (1).
Hydrogen atoms are omitted for clarity.
were unsuccessful. The 31P NMR spectra of 5 recorded at
room temperature and at low temperature (193 K, C7D8)
show a single signal shifted only by ca. 3 ppm to lower field
relative to the signal of the free ligand and suggest a
symmetrical weak phosphorus-gallium interaction of both
phosphinoarylthiolato ligands.
The reaction of AsSH with GaCl3 (in the presence of NEt3
as base) in different molar ratios and reaction conditions led
to white solids with very low solubility, which could not be
characterized. The equimolar reaction of AsSH with GaMe3
in toluene led to [GaMe2{(µ2-SC6H4-2-AsPh2)-κS}]2 (6;
Scheme 1). Attempts to replace more methyl groups were
unsuccessful. Like 3, 6 was also obtained as major product
in the 2:1 or 3:1 reaction (AsSH/GaMe3) and under different
reaction conditions (room temperature or refluxing toluene).
For the preparation of GatBu{(SC6H4-2-AsPh2)-κ2S,As}-
{(SC6H4-2-AsPh2)-κS} (7; Scheme 1) a similar procedure
1
as for 5 was employed. The H NMR spectrum of the
reaction product showed two sets of signals for the aromatic
and aliphatic protons, assigned to complex 7 and probably
GatBu2{(SC6H4-2-AsPh2)-κS,As}. Attempts to reproduce and
isolate 7 always led to a mixture of products. However a
few crystals of compound 7 were obtained from an n-hexane
solution of this mixture at room temperature over 2 days.
MolecularStructuresofComplexes1-7.GaCl{(SC6H4-
2-PPh2)-K2S,P}2 (1). The gallium atom in 1 is coordinated
by the chlorine atom and two chelating ligands in a trigonal-
bipyramidal geometry (Figure 1). The two phosphorus atoms
occupy the axial positions [P(1)-Ga(1)-P(2) 165.58(3)°]
(Table 2). The chlorine and the two sulfur atoms are in the
equatorial plane. The angles involving the chlorine atom
[S(1)-Ga(1)-Cl(1) 115.76(3)° and S(2)-Ga(1)-Cl(1)
114.40(3)°] are smaller than the S(2)-Ga(1)-S(1) bond
angle 129.48(4)°, a difference that is probably imposed by
the structure of the ligand.
Attempts to replace more than one alkyl group in GaR3
by phosphinoarylthiol were unsuccessful in case of GaMe3.
Compound 3 was the only product even when a 2:1 or 3:1
(PSH/GaMe3) molar ratio was used. When PSH was treated
with GatBu3 in a 2:1 or 3:1 molar ratio either at room
temperature or in boiling n-hexane (19 h), a mixture of
products was obtained.
The 2:1 reaction led (according to the 31P NMR spectra)
to a mixture of 4 (ca. 25%), GatBu{(SC6H4-2-PPh2)-
κ2S,P}{(SC6H4-2-PPh2)-κS} (5; ca. 20%), unconsumed PSH
(ca. 50%), and small amounts of 2 (ca. 1%), as well as some
decomposition products. Attempts to obtain 5 as a major
product by a 3:1 reaction of PSH with GatBu3 using different
t
refluxing times or by a 1:1 reaction of 1 with BuLi or the
equimolar reaction of complex 4 with PSH (ca. 20 h reflux)
(29) Bhattacharya, S.; Seth, N.; Srivastava, D. K.; Gupta, V. D.; No¨th, H.;
Thomann-Albach, M. J. Chem. Soc., Dalton Trans. 1996, 2815–2820.
(30) Carty, A. J. Coord. Chem. ReV. 1969, 4, 29–39.
The angles formed between equatorial and axial ligands
range from 80.27(3)° to 99.74(4)°. The Ga(1)-Cl(1) bond
length of 2.2161(9) Å is similar to those in related trigonal-
(31) Cheng, F.; Hector, A. L.; Levason, W.; Reid, G.; Webster, M.; Zhang,
W. Inorg. Chem. 2007, 46, 7215–7223.
(32) Calculations performed at the B3LYP/6-31G(d) level of theory.
bipyramidal complexes: 2.193(3)
Å for GaCl{PhC-
Inorganic Chemistry, Vol. 47, No. 23, 2008 11289

Va˘lean et al.
Table 2. Selected Bond Lengths (Å) and Bond Angles (deg) in
Compound 1
Ga(1)-Cl(1)
Ga(1)-S(1)
Ga(1)-S(2)
Ga(1)-P(1)
Ga(1)-P(2)
2.2161(9)
2.295(1)
2.270(1)
2.5872(1)
2.4927(9)
Cl(1)-Ga(1)-S(1)
Cl(1)-Ga(1)-S(2)
S(2)-Ga(1)-S(1)
Cl(1)-Ga(1)-P(1)
Cl(1)-Ga(1)-P(2)
S(1)-Ga(1)-P(2)
S(2)-Ga(1)-P(2)
S(1)-Ga(1)-P(1)
S(2)-Ga(1)-P(1)
P(2)-Ga(1)-P(1)
115.76(3)
114.40(3)
129.48(4)
94.67(4)
99.74(4)
93.23(3)
84.05(3)
80.27(3)
90.17(3)
165.58(3)
(S)CHC(O)Ph}229 and 2.195(1) Å for {H2B(pz)2}2GaCl (pz
) pyrazolyl).33 The Ga-S bond lengths of 2.270(1) and
2.295(1) Å are similar to those described for other five-
coordinate complexes (e.g., GaCl{PhC(S)CHC(O)Ph}2
2.274(2) Å).29 The gallium-phosphorus bond lengths are
well within the normal range associated with such bonds
[2.4-2.7 Å].7,8,34,35 The Ga(1)-P(1) bond length [2.5872(1)
Å] exceeds the Ga(1)-P(2) bond length [2.4927(9) Å].
However, the average Ga-P bond length [avg 2.54 Å]
greatly exceeds those observed in the tetracoordinate gal-
lium(III) phosphine complexes GaCl3(PMe3) [2.353(2) Å]36
or GaCl3{P(SiMe3)3} [2.379(5) Å]37 but is smaller than the
Ga-P bond length observed in Ga(CH2tBu)3(PHPh2) [2.683(5)
Å].35 Comparable Ga-P bond lengths were found in
GaMe3(dppe) (dppe ) bis(diphenylphosphino)ethane) [2.563-
(3) Å],38 GaClPh2{P(SiMe3)3} [2.459(2) Å], GaPh3-
{P(SiMe3)3} [2.539(6) Å], [Ga(CH2 Bu)(PPh2)2]2 [Ga-Pbr
2.4689(9) Å],39 [GaMe2(PPh2)]3 [2.433(1) Å],40 or GaClMe2-
(dppm-κP)(dppm)bis(diphenylphosphino)methane)[2.535(2)
Å].41
Ga{(SC6H4-2-PPh2)-K2S,P}{(SC6H4-2-PPh2)-KS}2 (2).
The structure of 2 (Figure 2, Table 3) consists of discrete
molecules with the gallium atom in a distorted tetrahedral
environment, coordinated by three 2-(diphenylphosphi-
no)benzenethiolato ligands.
Figure 2. Molecular structure of Ga{(SC6H4-2-PPh2)-κ2S,P}{(SC6H4-2-
PPh2)-κS}2 (2). Hydrogen atoms are omitted for clarity.
Table 3. Selected Bond Lengths (Å) and Bond Angles (deg) in
Compound 2
Ga(1)-S(1)
Ga(1)-S(2)
Ga(1)-S(3)
Ga(1)-P(1)
Ga(1)· · ·P(2)
Ga(1)· · ·P(3)
2.294(1)
2.2579(9)
2.2696(9)
2.3923(8)
3.241
S(2)-Ga(1)-S(3)
S(2)-Ga(1)-S(1)
S(3)-Ga(1)-S(1)
S(2)-Ga(1)-P(1)
S(3)-Ga(1)-P(1)
S(1)-Ga(1)-P(1)
116.73(3)
110.78(3)
107.10(3)
121.27(3)
110.12(3)
85.79(3)
4.468
8
t
Table 4. Selected Bond Lengths (Å) and Bond Angles (deg) in
Compounds 3 and 4
3
4
Ga(1)-C(19)
Ga(1)-C(20)
Ga(1)-S(1)
Ga(1)-P(1)
1.958(3) Ga(1)-C(23)
1.959(4) Ga(1)-C(19)
2.3109(9) Ga(1)-S(1)
2.4602(8) Ga(1)-P(1)
2.005(4)
2.017(4)
2.343(1)
2.5003(9)
C(19)-Ga(1)-C(20) 124.0(2)
C(23)-Ga(1)-C(19) 122.2(2)
C(19)-Ga(1)-S(1)
C(20)-Ga(1)-S(1)
C(19)-Ga(1)-P(1)
C(20)-Ga(1)-P(1)
S(1)-Ga(1)-P(1)
109.1(1)
112.1(1)
114.7(1)
106.8(1)
82.73(3)
C(23)-Ga(1)-S(1)
C(19)-Ga(1)-S(1)
C(23)-Ga(1)-P(1)
C(19)-Ga(1)-P(1)
S(1)-Ga(1)-P(1)
111.1(1)
110.0(1)
112.8(1)
111.1(1)
82.72(3)
One of the ligands is chelating while the other two are
coordinated only through their sulfur atoms, probably because
of steric hindrance. The S-Ga-S bond angles range from
107.10(3) to 116.73(3)°, and the S-Ga-P bond angles range
from 85.79(3) (bite angle of the chelating ligand) to
121.27(3)°.
H2O.42 On the other hand, the Ga(1)-P(1) bond length
[2.3923(8) Å] is comparable to the shortest reported
gallium-phosphorus bond of 2.353(2)
Å found in
GaCl3(PMe3)36 and significantly shorter than that for the five-
coordinate complex 1 [avg Ga-P 2.54 Å], as expected. This
distance, indicative of the Lewis acidic nature of the metal
center, is approximately the sum of the covalent radii [ca.
2.30 Å].38 The other phosphorus atoms are not coordinated
to gallium, but the Ga(1) · · · P(2) distance of 3.241 Å is
shorter than the sum of the van der Waals radii [3.67 Å],43
which could be indicative of some degree of Ga· · ·P
interaction.
A different behavior was observed for 2 in solution
compared with the solid state: the 31P NMR spectra suggest
noncoordinating phosphine groups, while in the solid state
one of the three phosphorus atoms is coordinated to gallium.
The mean Ga-S bond length of 2.283(1) Å is close to those
found in gallium complex 1 and [HNEt3][Ga{SC(O)Ph}4]·
(33) Reger, D. L.; Knox, S. J.; Lebioda, L. Inorg. Chem. 1989, 28, 3092–
3093.
(34) O’Hare, D.; Foord, J. S.; Page, T. C. M.; Whitaker, T. J. J. Chem.
Soc., Chem. Commun. 1991, 1445–1447.
(35) Banks, M. A.; Beachley, O. T., Jr.; Maloney, J. D.; Rogers, R. D.
Polyhedron 1990, 9, 335–342.
(36) Carter, J. C.; Jugie, G.; Enjalbert, R.; Galy, J. Inorg. Chem. 1978, 17,
1248–1254.
(37) Janik, J. F.; Baldwin, R. A.; Wells, R. L.; Pennington, W. T.; Schimek,
G. L.; Rheingold, A. L.; Liable-Sands, L. M. Organometallics 1996,
15, 5385–5390.
(38) Boardman, A.; Small, R. W. H.; Worrall, I. J. Inorg. Chim. Acta 1986,
119, L13–L14.
(39) Beachley, O. T., Jr.; Maloney, J. D.; Rogers, R. D. Organometallics
1993, 12, 229–232.
(40) Robinson, G. H.; Burns, J. A.; Pennington, W. T. Main Group Chem.
1995, 1, 153–158.
(41) Schmidbaur, H.; Lauteschla¨ger, S.; Mu¨ller, G. J. Organomet. Chem.
1985, 281, 25–32.
(42) Deivaraj, T. C.; Lin, M.; Loh, K. P.; Yeadon, M.; Vittal, J. J. J. Mater.
Chem. 2003, 13, 1149–1155.
(43) Bondi, A. J. Phys. Chem. 1964, 68, 441–451.
11290 Inorganic Chemistry, Vol. 47, No. 23, 2008

When Arsine Makes the Difference
Figure 5. Molecular structure of GatBu{(SC6H4-2-PPh2)-κ2S,P}{(SC6H4-
2-PPh2)-κS} (5). Hydrogen atoms are omitted for clarity. Complex 7 is
isostructural.
Figure 3. Molecular structure of GaMe2{(SC6H4-2-PPh2)-κ2S,P} (3). Only
one of two independent molecules found in the asymmetric unit is shown.
Hydrogen atoms are omitted for clarity.
Table 5. Selected Bond Lengths (Å) and Angles (deg) in Compounds 5
and 7
5 (E ) P)
7 (E ) As)
Ga(1)-C(37)
1.977(3)
2.2726(7)
2.2777(8)
2.5182(9)
3.191
1.98(1)
2.277(3)
2.268(3)
2.689(2)
3.029
Ga(1)-S(1)
Ga(1)-S(2)
Ga(1)-E(2)
Ga(1)· · ·E(1)
C(37)-Ga(1)-S(1)
C(37)-Ga(1)-S(2)
S(2)-Ga(1)-S(1)
C(37)-Ga(1)-E(2)
S(1)-Ga(1)-E(2)
S(2)-Ga(1)-E(2)
117.1(1)
125.1(1)
112.90(3)
110.6(1)
98.69(3)
81.95(3)
119.8(4)
125.2(4)
113.4(1)
107.1(3)
94.2(1)
80.4(1)
[2.4602(8) Å (3) and 2.5003(9) Å (4)], and they are longer
than that found in tetra-coordinate compound 2 but shorter
than those observed in five-coordinate complex 1.
Figure 4. Molecular structure of GatBu2{(SC6H4-2-PPh2)-κ2S,P} (4).
GatBu{(SC6H4-2-PPh2)-K2S,P}{(SC6H4-2-PPh2)-KS} (5)
and GatBu{(SC6H4-2-AsPh2)-K2S,As}{(SC6H4-2-AsPh2)-
KS} (7). X-ray structure analysis revealed the isostructural
complexes GatBu{(SC6H4-2-EPh2)-κ2S,E}{(SC6H4-2-EPh2)-
κS} (E ) P (5), As (7)) (Figure 5, Table 5). In both
compounds, the gallium atom is coordinated in a distorted
tetrahedral fashion by two sulfur atoms and one phosphorus
or arsenic atom from two PS- or AsS- ligands, and one tert-
butyl group.
The Ga-S, Ga-C, and Ga-P bond lengths for com-
pounds 5 and 7 are in the same range as those in 1-4. The
Ga(1)-As(2) bond length of 2.689(2) Å in 7 exceeds that
observed for known Ga-As bonds, for example, in the
adduct GaI3(AsPh3) [2.489(2) Å]9 or covalent bonds in
Ga{As(C6H2Me3)2}3 [2.470(1)-2.508(1) Å],48 [GaPh2-
{As(CH2SiMe3)2}]2 [2.518(1)-2.530(1) Å],49 [GaMe2-
(AstBu2)]2 [2.541(1)-2.558(1) Å],50 GatBu2(AstBu2) [2.446(3)
Å],18 GatBu2{As(SiPh3)CH(SiMe3)2} [2.458(1) Å],51
Hydrogen atoms are omitted for clarity.
Exchange between the hemilabile ligand and the solvent or
just hemilability of the ligand may account for the structure
in solution.
GaMe2{(SC6H4-2-PPh2)-K2S,P} (3) and GatBu2{(SC6H4-
2-PPh2)-K2S,P} (4). Two structurally independent molecules
were found in the asymmetric unit of 3 (no significant
differences in bond lengths and angles between the molecules
were observed). Selected bond lengths and angles are given
in Table 4.
In 3 (Figure 3) and 4 (Figure 4), the gallium atom is
coordinated in a distorted tetrahedral fashion by one sulfur
atom, one phosphorus atom, and two alkyl (methyl or tert-
butyl) groups. The Ga-S and Ga-C bond lengths in 3 are
slightly smaller than those found in 4 but lie in the same
range as those found in the literature for similar com-
plexes.44-47 The Ga-P bond lengths are slightly different
(44) Boardman, A.; Jeffs, S. E.; Small, R. W. H.; Worrall, I. J. Inorg. Chim.
(48) Pitt, C. G.; Higa, K. T.; McPhail, A. T.; Wells, R. L. Inorg. Chem.
1986, 25, 2483–2484.
(49) Wells, R. L.; Purdy, A. P.; McPhail, A. T.; Pitt, C. G. J. Organomet.
Chem. 1986, 308, 281–288.
Acta 1985, 99, L39–L40.
(45) Hoffman, B. G.; Burschka, C. J. Organomet. Chem. 1984, 267, 229–
236.
(46) Keys, A.; Bot, t S.G.; Barron, A. R. Polyhedron 1998, 17, 3121–
3130.
(47) Coward, K. M.; Jones, A. C.; Steiner, A.; Bickley, J. F.; Pemble, M. E.;
Boag, N. M.; Rushworth, S. A.; Smith, L. M. J. Mater. Chem. 2000,
10, 1875–1880.
(50) Arif, A. M.; Benac, B. L.; Cowley, A. H.; Geerts, R.; Jones, R. A.;
Kidd, K. B.; Power, J. M.; Schwab, S. T. J. Chem Soc., Chem.
Commun. 1986, 1543–1545.
(51) Petrie, M. A.; Power, P. P. J. Chem. Soc., Dalton Trans. 1993, 1737–
1745.
Inorganic Chemistry, Vol. 47, No. 23, 2008 11291

Va˘lean et al.
Ga-C bond lengths [1.946(2) and 1.948(2) Å] are within
the expected range. Unexpectedly, the arsenic atom of the
ligand is not coordinated to gallium, and AsS- acts as a
monodentate ligand, unlike PS- in 3, for which bidentate
coordination was found.
TheintramolecularS(1) · · ·S(1)′(3.434Å)andGa(1) · · ·Ga(1)′
[3.418 Å] distances are shorter than the sum of the van der
Waals radii of the atoms involved, which could be indicative
of some degree of S · · ·S and Ga · · ·Ga interactions (∑Ga · · ·Ga
) 3.74 Å, ∑S · · · S ) 3.6 Å).43 Similar Ga · · · Ga distances
were observed in [GaMe2(µ-SC6F5)]2 [3.397 Å],54 longer
distances in [GaPh2(µ-SEt2)]2 [3.257 Å]45 and [NEt4]2[Ga2S2(µ-
SPh)4] [2.943 Å],53 and shorter ones in [GatBu2(µ-SPh)]2
[3.663 Å].46
The packing diagram of 6 shows the molecules arranged
in columns along the crystallographic b axis, connected
through H(phenyl)-π interactions [π stacking avg H(Ph) · · ·Ph
2.785 Å and H(Ph) · · · S 2.924 Å interactions].
Chelate or Bridging Ligands in 3 and 6. Complexes 3
and 6 represent relatively rare examples31 of different
coordination behavior of the two very similar ligands PSH
and AsSH toward the same metal complex fragment, GaMe2.
While a monomeric structure with a chelating phosphanyl-
arylthiolato ligand is observed in GaMe2{(SC6H4-2-PPh2)-
κ2S,P} (3), a dimeric arsanylarylthiolato-bridged complex
[GaMe2{(µ2-SC6H4-2-AsPh2)-κS}]2 (6) is obtained with the
corresponding AsS ligand. In order to understand this
difference in the behavior of the PS- and AsS- ligand in 3
and 6, molecular orbital calculations on models H-PS and
H-AsS, in which the substituents on phosphorus or arsenic
are replaced by hydrogen, and their complexes with GaMe2
(Scheme 2) were performed at the B3LYP/6-31G(d)55 level
of theory. The results for GaMe2(H-PS) and GaMe2-
(H-AsS) with varying coordination of the ligand, mono-
dentate through sulfur (a, a′), bidentate (chelate) (b, b′), and
thiolato-bridged to form dimers (c, c′), are summarized in
Table 7.
Figure 6. Molecular structure of [GaMe2{(µ2-SC6H4-2-AsPh2)-κS}]2 (6).
Hydrogen atoms are omitted for clarity.
Table 6. Selected Bond Lengths (Å) and Bond Angles (deg) in
Compound 6
Ga(1)· · ·Ga(1)′
Ga(1)· · ·As(1)
S(1)· · ·S(1)′
C(1)-Ga(1)
C(2)-Ga(1)
S(1)-Ga(1)
S(1)-Ga(1)′
3.418
4.951
3.434
1.946(2)
1.948(2)
2.4075(6)
2.4372(6)
C(1)-Ga(1)-C(2)
C(1)-Ga(1)-S(1)
C(1)-Ga(1)-S(1)′
C(2)-Ga(1)-S(1)
C(2)-Ga(1)-S(1)′
C(3)-S(1)-Ga(1)
C(3)-S(1)-Ga(1)′
Ga(1)-S(1)-Ga(1)′
S(1)-Ga(1)-S(1)′
125.9(1)
110.04(7)
102.71(7)
107.86(8)
114.31(7)
107.68(7)
110.37(7)
89.74(2)
90.26(2)
or [(Cl3Ga){Me2AsCH2C(Me)(CH2AsMe2)2}GaCl2][GaCl4]
[2.435(1)-2.465(2) Å].52 The reason could be steric hin-
drance in compound 7.
The other phosphorus or arsenic atom is not bonded to
the gallium atom. However, the Ga · · · E distances [3.191(5)
and 3.029(7) Å] are shorter than the sum of the van der Waals
radii (∑Ga· · · P ) 3.67 Å, ∑Ga · · · As ) 3.72 Å)43 and
suggest interaction between the gallium and phosphorus or
arsenic atoms.
[GaMe2{(µ2-SC6H4-2-AsPh2)-KS}]2 (6). Compound 6
(Figure 6 and Table 6) consists of a dimer with a central
planar almost rectangular four-membered Ga2S2 ring
[Ga(1)-S(1)-Ga(1)′ 89.74(2)°, S(1)-Ga(1)-S(1)′ 90.26(2)°].
Planar Ga2S2 rings were also found in [GaI2(µ-SMe)]244 and
[GaPh2(µ-SEt)]2.45
The gallium atoms are coordinated in a distorted tetrahe-
dral fashion by two thiolato and two methyl groups. The
Ga-S bond lengths [2.4075(6) and 2.4372(6) Å] are larger
than those in 3 and [NEt4]2[Ga2S2(SPh)4] [2.264(1) to
2.288(1) Å]53 but comparable with those found in other four-
membered Ga2S2 rings, [GatBu2(µ-SPh)]2 [2.421(2)-2.445(2)
Å]46 and [GaMe2(µ-SC6F5)]2 [2.436(3)-2.460(2) Å].54 The
Summary
(Organo)gallium compounds were obtained by treating
2-EPh2-C6H4SH (E ) P, As) with GaCl3 or GaR3 (R ) Me,
tBu) in different molar ratios and under different reaction
conditions. With the exception of compounds 5 and 7, all
complexes were obtained in high yield. In complexes 2-7,
Scheme 2. Computed Models of GaMe2{SC6H4-2EPh2} (E ) P, As)
11292 Inorganic Chemistry, Vol. 47, No. 23, 2008

When Arsine Makes the Difference
Table 7. Total (au) and Relative (kcal/mol) Energies of the Monomeric Monodentate or Chelate Complexes and Dimers of the Model Systems
GaMe2(H-ES) (E ) P, As)
2(E(chelate)
- E(dimer))
(kcal/mol)
chelate/monodentate
relative energy
(kcal/mol)
2(E(monodentate)
- E(dimer))
(kcal/mol)
total energy (au)
a (E ) P) monodentate H-PS
-2976.283 958 5
-2976.292 115 1
-5952.595 310 4
-4870.562 673 9
-4870.562 596 9
-9741.150 688 9
+5.12
+17.19
b (E ) P) chelate H-PS
+6.95
0.0
c (E ) P) dimer Ga2S2 [GaMe2(µ2-H-PS-κS)]2
a′ (E ) As) monodentate H-AsS
b′ (E ) As) chelate H-AsS
0.0
0.0
+15.90
0.0
+0.05
+16.00
c′ (E ) As) dimer Ga2S2 [GaMe2(µ2-H-AsS-κS)]2
0.0
0.0
the gallium atom is tetracoordinate, whereas chloro complex
1 has a coordination number of five and trigonal-bipyramidal
geometry.
Although, similar phosphorus and arsenic ligands usually
exhibit the same coordination behavior toward the same
metal complex fragment, different structures are observed
here: a monomeric structure with a chelating phosphi-
noarylthiolato ligand in GaMe2{(SC6H4-2-PPh2)-κ2S,P} (3)
and a dimeric arsinoarylthiolato-bridged complex [GaMe2{(µ2-
SC6H4-2-AsPh2)-κS}]2 (6). B3LYP/6-31G(d) calculations
show that although the dimer is thermodynamically favored
for both ligands, the formation of 3 is due to the combination
of higher stability of the chelate compared with the mono-
dentate phosphorus ligand and a higher barrier for the ring
opening of the PS- than of the AsS-chelate.
(52) Cheng, F.; Hector, A. L.; Levason, W.; Reid, G.; Webster, M.; Zhang,
W. Dalton Trans. 2007, 2207–2210.
(53) Maelia, L. E.; Koch, S. A. Inorg. Chem. 1986, 25, 1896–1904.
(54) Hendershot, D. G.; Kumar, R.; Barber, M.; Oliver, J. P. Organome-
tallics 1991, 10, 1917–1922.
(55) (a) Becke, A. D. J. Chem. Phys. 1993, 98, 5648–5652. (b) Lee, C.;
Yang, W.; Parr, R. G. Phys. ReV. B 1988, 37, 785–789. (c) Stephens,
P. J.; Devlin, F. J.; Chabalowski, C. F.; Frisch, M. J. J. Phys. Chem.
1994, 98, 11623–11627. (d) Vosko, S. H.; Wilk, L.; Nusair, M Can.
J. Phys. 1980, 58, 1200–1211.
Acknowledgment. This work was generously supported
by the EU Marie-Curie Training Site HPMT-CT-2000-00110,
the Deutscher Akademischer Austauschdienst (DAAD) A/06/
09017, SOE Programme and CEEX-OPTOLUM/CNCSIS-
710 - Romanian Research Grants.
IC801582B
Inorganic Chemistry, Vol. 47, No. 23, 2008 11293