Efficient methods for the preparation of bromine-containing exo- nido- and closo-ruthenacarborane clusters.

An efficient method for the synthesis of bromine-containing exo- nido-clusters of a general formula exo-5,6,10-[Br(PhP)Ru]-5,6,10-(μ-H)-10-H-7,8-R- nido-7,8-CBH (R = H, Me) was developed using the reactions of RuBr(PPh) with [K][7,8-R-7,8- nido-CBH]. Replacement of the phosphine ligands in the starting exo- nido-cluster (R = H) with the diphosphine ones afforded a series of diamagnetic (18-electron) closo-bromoruthenacarboranes, 3-Br-3,3-[κ-PhP(CH)PPh]-3-H- closo-3,1,2-RuCBH ( n = 3−5). A mild thermal method of the halide ligands exchange (Cl → Br) upon heating of diamagnetic chlorine-containing complexes 3,3-[κ-PhP(CH)PPh]-3-H-3-Cl- closo-3,1,2-RuCBH ( n = 3−5) with excess of CBr in benzene (70-80 °C) was suggested for the synthesis of paramagnetic (17-electron) bromine-containing ruthenacarboranes, 3-Br-3,3-[κ-PhP(CH)PPh]- closo-3,1,2-RuCBH ( n = 3, 4) or 3-Br-3,3,8-[κ-Ph(CH)PPh]-μ-[InlineMediaObject not available: see fulltext.]. Paramagnetic chlorine-containing clusters 3-Cl-3,3-[κ-PhP(CH)PPh]- closo-3,1,2-RuCBH ( n = 2−4) were alternatively used as the starting compounds in the exchange reaction. Complexes with dppp and dppb (dppp is 1,3-bis(diphenylphosphino)propane, dppb is 1,4-bis(diphenylphosphino)butane) were used as examples to study the thermal reactions (toluene, 110 °C) leading in the presence of CBr to paramagnetic mono( P- o-phenylene)- and bis( P, P- o-phenylene)cycloboronated clusters, 3-Br-3,3,8-[κ-Ph(CH)PPh]-μ-[InlineMediaObject not available: see fulltext.] and 3-Br-3,3,4,8-[κ-Ph(CH)P]-μ-[InlineMediaObject not available: see fulltext.] ( n = 3, 4). The compounds obtained were characterized by NMR spectroscopy (in the case of diamagnetic complexes), ESR spectroscopy and mass spectrometry (in the case of paramagnetic compounds). X-ray diffraction experiments were carried out for two cycloboronated paramagnetic complexes. [ABSTRACT FROM AUTHOR]