Reactions and coordination properties of the first secondary carbaboranyldiphosphane: 1,2-bis(phenylphosphanyl)-1,2-dicarba-closo-dodecaborane(12)

When a mixture of stereoisomers of rac- and meso-1,2-bis(phenylphosphanyl)-1 ,2-dicarba-closo-dodecaborane (12) (1a, b; 1a/1b = 3:1) is treated with [Cp2ZrMe2] in boiling toluene for 2 h, the formation of three phosphorus-containing products, namely meso-[Cp2Zr(PPh)(3)] (3), (PPh)(4) (4) and (PPh)(5) (5), ratio 2.8:1.1:1.0, was observed by P-31-NMR spectroscopy In the B-11-NMR spectrum of the reaction mixture, only signals for 1,2-dicarba-closo-dodecaborane(12) were observed. When zirconocene, prepared in situ from [Cp(2)ZrCl2] and BuLi, was treated with 1a, b at low temperature and then heated to reflux in toluene for 2 h, only formation of 3 and 1,2-dicarba-closo-dodecaborane(l2) was observed. The mixture of stereoisomers of la, b reacts with CuCl in THF to give rac- and meso-[CuCl(THF)(1,2-(PHPh)(2)C2B10H10)] (7a, b), which is only stable in THF solution and loses THF in vacuo over several hours to yield the insoluble colorless complex [CuCl(1,2-(PHPh)(2)C2B10H10)](n) (8) In THF solution, 7 reacts with PPh3 to give the stable isolable complex [CuCl(PPh3)(1,2-(PHPh)(2)C2B10H10)] (9.) NO reaction of 1a, b is observed with [Cp'Mo(CO)(3)](2) (Cp' = C5H4Me) in boiling THF, while only decomposition occurs in boiling toluene. However, [(NBD)Mo(CO)(4)] (NBD = norbomadiene) reacts smoothly with 1a in toluene at room temperature to give cis-rac-[Mo(CO)(4)(1,2-(PHPh)(2)C2B10H10)] (10). Compounds 7, 9, and 10 were characterized spectroscopically (H-1, P-31, B-11, C-13 NMR, IR), and an X-ray structure determination was carried out on 10.