摘要:
                                The reactions of cyclodiphosphazanes [PhNP(OR)]2 (R = CH2CF3 (1) and C6H4Me-p (2)) with Group 6 metal carbonyl derivatives have been investigated. The stereochemistry of the ligand appears to play a significant role in determining its coordination behaviour. The cyclodiphosphazane 1 (isolated as the trans-isomer) affords the dinuclear complexes 9-11 in which the two metal centres are bridged by the diphosphazane ligand. In contrast the cyclodiphosphazane 2 (isolated as a 3/1 mixture of cis- and trans-isomers) yields the mononuclear complexes 3-7 in which the cyclodiphosphazane is coordinated in the eta1-fashion. The structures of [W(CO4(NHC5H10){(PhNP(OC6H4Me-p))2}] (6) and [{Mo(CO)4(NHC5H10)}2{mu-[PhNP(OCH2CF3)]2}] (9a) have been determined by X-ray crystallography.