Degradation and modification of metallaboranes. Part 4: Synthesis and characterization of a series of hybrid bimetallaborane clusters of the type [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-3-(BH2PPh2)CxHyPPh2RuCl2(p-cym)]

Reactions between a series bidentate phosphines, with the general formula PPh2(CH2)nPPh2, and the air stable hexaborane(10) analogue [2,2,2-(PPh3)2(CO)-nido-2-OsB5H9] (1), afford species of the type [{(PPh3)2(CO)OsB4H7}-3-{BH2PPh2(CH2)n(PPh2)}] (2) which contain a pendent PPh2 group. In solution 2 can undergo an intramolecular substitution reaction to form the species [{(PPh3)(CO)OsB4H7}-η2-3,2-{BH2PPh2(CH2)n(PPh2)}] (4). In spite of this, chemistry at the pendent PPh2 group may be studied and herein are reported the results of reactions of 2 with the organometallic reagent [(p-cym)RuX2]2 (X = Cl, I) to afford hybrid bimetallaborane clusters of the type [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-3-(BH2PPh2)CxHyPPh2RuCl2(p-cym)] (5) The species obtained include [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7 · 3-(BH2 · dppe · Ru(p-cym)Cl2)] (5a), [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7 · 3-(BH2 · dppp · Ru(p-cym)Cl2)] (5b), [2,2,2-(PPh3)2(CO)-2-nido-OsB4H7 · 3-(BH2 · dpph · Ru(p-cym)Cl2)] (5c), [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-3-(BH2 · dppx · Ru(p-cym)Cl2)] (5d) and [2,2,2-(PPh3)2(CO)-nido-2-OsB4H7-3-(BH2 · dppe · Ru(p- cym)I2)] (6). Species 5d was also prepared from the reaction between 1 and the known compound · [dppx · Ru(p-cym)Cl2. Species 5a–5d and 6 were characterized by elemental analysis, high resolution mass spectrometry and NMR spectrometry; the latter affording some novel features for this series of compounds. Structure determination by X-ray diffraction was not successful but a structure of the analogue [BH3 · (PPh2)(CH2)6(PPh2) · Ru(p-cym)Cl2] (7) is reported.