Oxidative addition of halogens to MoRu(CO) 6 (dppm) 2 Mozhgan Khorasani-Motlagh a , Nasser Safari b , Craig B. Pamplin c , Brian O. Patrick c , Brian R. James c, * a Department of Chemistry, University of Sistan and Baluchestan, Zahedan, Iran b Department of Chemistry, University of Shahid Beheshti, Tehran, Iran c Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, Canada V6T 1Z1 Received 12 June 2003; accepted 26 June 2003 Published online: 22 July 2003 Abstract Halogens oxidatively add to MoRu(CO) 6 (l-dppm) 2 (1) at ambient temperature to yield [(CO) 2 Mo(l-X)(l-CO)(l- dppm) 2 Ru(CO) 2 ] þ [Mo(CO) 4 X 3 ]  , where X ¼ Cl (2) or I (3), dppm ¼ Ph 2 PCH 2 PPh 2 , and the l-CO is semi-bridging. Complexes 2 and 3 have been characterized by elemental analysis, conductivity, and NMR spectroscopy, while the molecular structure of 3 has been determined by X-ray crystallography. Ignoring a weak metal–metal bond interaction, the cation of 3 is most easily described as pseudo-octahedral at Ru(II) and Mo(0) centres; the anion is a monocapped octahedron that has been described previously. Ó 2003 Elsevier B.V. All rights reserved. Keywords: Molybdenum complex; Ruthenium complex; Bis(diphenylphosphino)methane; Halogen reactivity; Crystal structure; Semi-bridged carbonyl 1. Introduction Our group has reported on the reactivity of H 2 S with monometallic Ru II [1] and dimetallic Pd I 2 (dppm) 2 cen- tres [2], and recently extended this H 2 S work to inter- action with the known [3], heterobimetallic complex MoRu(CO) 6 (dppm) 2 [4] (dppm ¼ Ph 2 PCH 2 PPh 2 and, in all the systems discussed in this paper, is coordinated in a bridging P,P-mode between two metals; for conve- nience, the l symbol is omitted). In both dimetallic systems, the final product is a bridged-sulfide species, and we discovered that the l-S can be recovered as el- emental sulfur by oxidation of the dimetallic l-sulfide species with halogens, the co-product being mono- or bimetallic halide species [2b]. This led us to a general investigation of the dimetallic precursors, including analogous Pd I 2 –l-bis(dialkylphosphino)methane com- plexes, with halogens [5]. This present paper reports on the halogen oxidation of MoRu(CO) 6 (dppm) 2 ; this species, first synthesized by Chaudret and co-workers [3] is commonly formulated as (CO) 3 Mo(dppm) 2 Ru(CO) 3 containing a Mo–Ru bond between formally zero-valent metal oxidation states, while an X-ray structural study (at least for a centrosymmetric, toluene solvated species) reveals five terminal CO ligands and one semi-bridged CO, although the structural analysis is complicated by half occupancy at each of the metal sites [3]. In our work reported here, the products are formed by a net oxida- tive addition of the halogens (X 2 ) to generate a salt, comprised of a cation that is most easily formulated as an Mo 0 –Ru II species and the known Mo II anions [Mo(CO) 4 X 3 ]  [6]. More generally, oxidative addition reactivity of low valent heterobimetallic precursor complexes containing dppm constitutes an area of continuing interest [3,4,7], although oxidative reactivity with halogens is not so common [5,7a]. 2. Experimental Toluene was dried by refluxing over Na/benzophe- none under Ar and distilled immediately before use; other Inorganic Chemistry Communications 6 (2003) 1175–1179 www.elsevier.com/locate/inoche * Corresponding author. Tel.: +1-604-822-6645; fax: +1-604-822- 2847. E-mail address: brj@chem.ubc.ca (B.R. James). 1387-7003/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved. doi:10.1016/S1387-7003(03)00217-X