Gallium and indium dithiocarboxylates: Synthesis, spectroscopic characterization and structure of [MeGa(S 2 Ctol) 2 ] Shamik Ghoshal a , Vimal K. Jain a, * , Dimple P. Dutta a , Prasad P. Phadnis b , Munirathinam Nethaji b a Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India b Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, India Received 5 September 2006; received in revised form 14 September 2006; accepted 14 September 2006 Available online 19 September 2006 Abstract Several gallium and indium dithiocarboxylate complexes of the type [Me n M(S 2 CR) 3n ](M = Ga, In; n = 0, 1, 2; R = phenyl (Ph), p-tolyl (tol), mesityl (Mes)) have been synthesized. These complexes were characterized by elemental analysis, IR, UV–vis and NMR ( 1 H, 13 C{ 1 H}) spectroscopy. Structure of [MeGa(S 2 Ctol) 2 ] was established by X-ray crystallography. The gallium atom adopts a distorted five coordinate geometry which is intermediate between trigonal bipyramidal and square pyramidal configurations. The complex [Me 2 InS 2 Ctol] underwent a two-step thermal decomposition leading to the formation of tetragonal b-In 2 S 3 . Ó 2006 Elsevier B.V. All rights reserved. Keywords: Gallium; Indium; Dithiocarboxylates; NMR; X-ray; In 2 S 3 1. Introduction Organometallic and classical complexes of group 13 ele- ments, particularly Ga and In, with chalcogen ligands are of considerable recent interest due to their diverse structural features [1] and their relevance as molecular precursors for metal chalcogenides [2–5]. Thus a variety of gallium and indium complexes with thiolates [6], pyridine-2-thiolate [7], monothiocarboxylate [8], and dithiolates (xanthates [9–11], dithiocarbamates [12,13], diorganodithio-phosphi- nate/-phosphates [14–17]) have been synthesized and char- acterized. Organogallium and indium thiolates, [R 2 MSR 0 ] 2 and [RM(SR 0 ) 2 ] 2 , are often isolated as dimers. The indium complexes have been employed as precursors for deposition of indium sulfide films, which in general contained a mixture of sulfides. The dithiolate complexes, in general, are mono- meric. Both classical and organoindium xanthate and dithiocarbamate complexes have shown promising poten- tial for the preparation of b-In 2 S 3 bulk, films and nanopar- ticles [4,10,11,13,17–19]. Structural aspects of tris chelates are now fairly well studied, whereas such investigations on organometallic dithiolates are limited to Et 2 In(S 2 CNEt 2 ) [4]. The synthetic aspects of monoorganometal dithiolate are scanty [17,20]. The dithiocarboxylates are a versatile family of dithio- late ligands [21] and their gallium and indium complexes may have potential as molecular precursors for metal sul- fides. In the light of the above and in pursuance of our work on gallium and indium dithiolate complexes we have synthesized dithiocarboxylates of gallium and indium and determined the structure of a monomethyl gallium dithio- late complex. 2. Results and discussion Treatment of trimethyl gallium/indium etherate with dithiocarboxylic acids in 1:1 and 1:2 stoichiometry gave di- and mono-methyl metal complexes (Scheme 1). The reaction of MCl 3 with the acids in 1:3 ratio in the presence 0022-328X/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.jorganchem.2006.09.029 * Corresponding author. Tel.: +91 22 2559 5095; fax: +91 22 2550 5151. E-mail address: jainvk@barc.gov.in (V.K. Jain). www.elsevier.com/locate/jorganchem Journal of Organometallic Chemistry 691 (2006) 5838–5844