New Coordination Modes of an Oxime Ligand in a Triosmium Cluster. Stabilization by Intra- and Intermolecular C−H···O Hydrogen Bonds

Abstract

Reaction of the hydroxyamine 7-chloro-4-(hydroxyamino)quinoline with the triosmium cluster Os 3 (CO) 10 (NCMe) 2 gave the complex (μ-H)Os 3 (CO) 10 (μ 2 -η 1 -O-C 9 H 6 N 2 Cl) ( 3 ), in which a new mode of μ 2 -η 1 - O -oximato ligand bridged two osmium centers by an oxygen atom. This complex was slowly converted to (μ-H)Os 3 (CO) 10 (μ 2 -η 2 -ON-C 9 H 6 NCl) ( 4 ), where an aromatic C−H moiety in the μ 2 -η 2 - ON -oximatoquinoline group formed an unusual short intramolecular C−H···O−N hydrogen bond and an intermolecular C−H···O C hydrogen bond simultaneously. The formation of the intramolecular hydrogen bond may provide a stabilization effect for the generation of the η 2 - ON complex 4 and a driving force for the transformation of 3 to 4 .