Acetylenic derivatives of metal carbonyls. Part XIII. Reactions of dodecarbonyltriosmium with aryl acetylenes

Abstract

Dodecacarbonyltriosmium reacts with acetylenic ligands L [L = Ph₂C₂, (p-ClC₆H₄)₂C₂, (p-CH₃C₆H₄)₂C₂] in n-heptane under reflux to yield complexes of general formula L₂Os₃(CO)₈. Analysis of their n.m.r. and mass spectra indicated the probable existence of a bridging hydrido-ligand. It is suggested that the stability of these compounds is due to a bond between a phenyl group and an osmium atom and the presence of a hydrido-ligand.

Complexes L₂Os₃(CO)₈ react with CO to give L₂Os₃(CO)₉, following second-order rate laws. Effect of ligand L on the reaction rate is discussed. Further action of CO on L₂Os₃(CO)₉ gives binuclear complexes L₂Os₂(CO)₆. Ligands L′ such as PF₃, PPh₃, AsPh₃, and SbPh₃ react with L₂Os₃(CO)₈ to give L₂Os₃(CO)₈L′, which are considered to be isostructural with L₂Os₃(CO)₉.