Binuclear (salen)osmium phosphinidine and phosphiniminato complexes

Abstract

The preparation of a number of binuclear (salen)osmium phosphinidine and phosphiniminato complexes using various strategies are described. Treatment of [Os VI(N)(L 1)(sol)](X) (sol = H 2O or MeOH) with PPh 3 affords an osmium(iv) phosphinidine complex [Os IV{N(H)PPh 3}(L 1)(OMe)](X) (X = PF 61a, ClO 41b). If the reaction is carried out in CH 2Cl 2 in the presence of excess pyrazine the osmium(iii) phosphinidine species [Os III{N(H)PPh 3}(L 1)(pz)](PF 6) 2 can be generated. On the other hand, if the reaction is carried out in CH 2Cl 2 in the presence of a small amount of H 2O, a μ-oxo osmium(iv) phosphinidine complex is obtained, [(L 1){PPh 3N(H)}Os IV-O-Os IV{N(H)PPh 3}(L 1)](PF 6) 23. Furthermore, if the reaction of [Os VI(N)(L 1)(OH 2)]PF 6 with PPh 3 is done in the presence of 2, the μ-pyrazine species, [(L 1){PPh 3N(H)}Os III-pz-Os III{N(H)PPh 3}(L 1)](PF 6) 24 can be isolated. Novel binuclear osmium(iv) complexes can be prepared by the use of a diphosphine ligand to attack two Os VIN. Reaction of [Os VI(N)(L 1)(OH 2)](PF 6) with PPh 2-CC-PPh 2 or PPh 2-(CH 2) 3-PPh 2 in MeOH affords the binuclear complexes [(MeO)(L 1)Os IV{N(H)PPh 2-R-PPh 2N(H)}Os IV(L 1)(OMe)](PF 6) 2 (R = CC 5, (CH 2) 36). Reaction of [Os VI(N)(L 2)Cl] with PPh 2FcPPh 2 generates a novel trimetallic complex, [Cl(L 2)Os IV{NPPh 2-Fc-PPh 2N}Os IV(L 2)Cl] 7. The structures of 1b, 2, 3, 4, 5 and 7 have been determined by X-ray crystallography. © The Royal Society of Chemistry 2011.