138151-30-1Relevant articles and documents
η1-P- and η2-O-P-Bonded (Ether-Phosphane)Osmium(II) Complexes and their Mutual Conversion
Lindner, Ekkehard,Rothfuss, Helmut,Fawzi, Riad,Hiller, Wolfgang
, p. 541 - 550 (2007/10/02)
Reactions of cis-Br2Os(CO)4 with the (ether-phosphane) ligands 2a-f results in the formation of the cis,cis,trans-complexes Br2Os(CO)2(P-O)2 (3a-f). 3b crystallizes in the monoclinic space group P21/c with Z = 4.Irradiation of 3a-f leads to the cleavage of a further CO group and the formation of an Os-O bond to give the mono(chelate) complexes Br2Os(CO)(P-O)P-O (5a-f), with one of the O,P ligands being bidentate. 5a-f exist as mixtures of different trans-P (A,B) and cis-P isomers (C-g).Dependent on the fact that a reversible cis/trans equilibrium or an irreversible trans->cis transformation is possible or that no trans-P isomers are present at any temperature, 5a-f may be classified in three categories.Interconversion of the isomers A-G results from dissociation of the η1-P coordinated ether-phosphane and concomitant occurrence of the 16e- species Br2Os(CO)(PO) (8).From temperature-dependent 31P(1H)-NMR spectroscopic investigations the temperature for the reversible opening of the metal-oxygen contact is determined.The reversible opening leads to the complexes Br2Os(CO)(P-O)2 (9) with a vacant coordination site depending on the Os-O bonding strength. 5a-f react with CO to give all-trans-Br2Os(CO)2(P-O)2 (4a-f).The action of the ether-phosphanes 2a-f on OsBr2(PPh3)4 (7) affords the bis(chelate complexes Br2Os(P-O)2 (6a-f) which add carbon monoxide to form all-trans-4a-f.Key Words: Ether phosphanes / Osmium(II) complexes / Conversion
