Allyl palladium dithiocarbamates and related dithiolate complexes as precursors to palladium sulfides Anthony Birri a , Benjamin Harvey a , Graeme Hogarth a, * , Elif Subasi b, * , Fadime Ug ˘ur c a Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK b Department of Chemistry, Faculty of Science and Arts, Dokuz Eylul University, 35160 Buca, _ Izmir, Turkey c Ege University, Faculty of Science, Department of Chemistry, Bornova, 35100 _ Izmir, Turkey Received 4 December 2006; received in revised form 9 February 2007; accepted 15 February 2007 Available online 21 February 2007 Abstract Allyl-palladium dithiocarbamate complexes, [Pd(allyl)(S 2 CNR 2 )], have been prepared from the addition of dithiocarbamate salts to [Pd(allyl)(l-Cl)] 2 and TGA and DSC studies have been carried out in order to assess their potential as MOCVD precursors to palladium sulfides. For comparison [(g 3 -C 4 H 7 )Pd(S 2 PPh 2 )] and [Pd(S 2 CNMeR) 2 ] (R = Bu, Hex) have also been prepared and tested as precursors. The unsymmetrical dithiocarbamate complex, [(g 3 -C 3 H 5 )Pd(S 2 CNMeHex)], which has a melting point of 65 °C was selected as the best single source precursor and thin films of predominantly Pd 2.8 S were deposited on glass slides. The crystal structures of [(g 3 - C 4 H 7 )Pd(S 2 CNMe 2 )], [(g 3 -C 4 H 7 )Pd(S 2 CNPr 2 )], [(g 3 -C 4 H 7 )Pd(S 2 PPh 2 )] and [Pd(S 2 CNMeBu) 2 ] are reported. All except [(g 3 - C 4 H 7 )Pd(S 2 CNPr 2 )] show weak intermolecular SH or PdH interactions. Ó 2007 Elsevier B.V. All rights reserved. Keywords: Dithiocarbamate; Palladium; Dithiolate; Allyl; MOCVD; X-ray; TGA; DSC 1. Introduction A range of palladium sulfides are known including PdS, PdS 2 , Pd 4 S and non-stoichiometric materials such as Pd 2.2 S and Pd 2.5 S. PdS itself is a semi-conductor (E g = 2 eV) which also finds use in a wide range of catalytic processes including hydrodesulfurization [1], hydrogenation [2] and the selective synthesis of methanol from carbon monoxide and hydrogen [3]. While PdS can easily be prepared upon addition of hydrogen sulfide to tetrachloropalladate(II), in common with other metal sulfides it can be difficult to process or engineer. Jain and co-workers have reported the formation of Pd 4 S upon heating thiolate-bridged com- plexes, [Pd(l-SR)(g 3 -C 4 H 7 )] 2 (R = Bu t , Ph, C 6 F 5 ), in xylene [4]. A better method of preparing such materials is to use metal organic chemical vapour deposition (MOCVD) from a single source precursor [5]. In this manner, thin films of PdS have been prepared by Zink and co-workers from the xanthate complex [Pd(S 2 COPr i ) 2 ], thermal decomposition at 350 °C producing polycrystalline tetragonal PdS on both glass slides and silicon wafers [6]. In 2002, O’Brien and co-workers reported the use of [Pd(S 2 CNMeHex) 2 ] as a precursor to the formation of thin films of PdS at 400–500 °C [7], and also prepared trioctyl- phosphineoxide (TOPO) capped nanoparticles of PdS upon injecting [Pd(S 2 CNMeHex) 2 ] in trioctylphosphine into TOPO at 250 °C. In our laboratory, we have been interested in developing volatile precursors for the deposition of palladium metal and palladium chalcogenides. For the deposition of thin films of palladium sulfides, we targeted allyl palladium dithiocarbamate complexes [8,9] since such materials are easy to prepare and handle and we have previously found that allyl palladium complexes exhibit relatively high vola- tility while decomposing cleanly. Herein, we report a com- parative study of the use of bis(dithiocarbamate) and allyl 0022-328X/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.jorganchem.2007.02.015 * Corresponding authors. E-mail address: g.hogarth@ucl.ac.uk (G. Hogarth). www.elsevier.com/locate/jorganchem Journal of Organometallic Chemistry 692 (2007) 2448–2455