Synthesis, characterization, reactivity and molecular structure of arene-osmium complexes: A new synthetic entry into (η 6-arene)osmium(II) chemistry

Abstract

A new convenient one-pot procedure for the preparation of the p-cymene-osmium dimer [(η 6- p-MeC 6H 4Pr i )OsBr 2] 2 ( 1) from potassium osmate K 2[OsO 2(OH) 4] is described. The analogous hexamethylbenzene complex [(η 6-C 6Me 6)OsBr 2] 2 ( 2) and a series of new arene-osmium complexes [(η 6- p-MeC 6H 4Pr i )OsLBr 2] ( 3– 9) (L = CO, PPh 3, PEt 3, PMePh 2, P(OMe) 3, P(OBu n ) 3 and P(OPh) 3) have been prepared from 1. The complex [(η 6-C 6Me 6)Os(CO)Br 2] ( 10) was obtained from 2. All the complexes were characterized spectroscopically by NMR and IR and by elemental analysis. Single crystal X-ray structures of [(η 6- p-MeC 6H 4Pr i )OsBr 2] 2 ( 1) and [(η 6- p-MeC 6H 4Pr i )Os(PPh 3)Br 2] ( 3) are reported. The reactions of some of these complexes with BrMg(CH 2) 3CH CH 2 and MeLi are also described.