Three isomeric triosmium clusters containing bridging ligands derived from the salicylaldimine PhCH2NCHC6H4OH-2

Abstract

[Os₃(CO)₁₀(MeCN)₂] reacts in refluxing benzene with the salicylaldimine PhCH₂NCHC₆H₄OH-2 to give the decacarbonyl cluster [Os₃H(CO)₁₀(µ-OC₆H₃CHNHCH₂Ph)] by metallation at the position ortho to the phenolic group. Thermolysis of this compound in refluxing heptane gives three isomers: [Os₃H(CO)₉(µ₃-OC₆H₃CHNHCH₂Ph)], [Os₃H(CO)₉(OC₆H₄CHNCH₂Ph)] in which the salicylaldiminate ligand chelates in a classical manner, and [Os₃H₂(CO)₉(µ₃-OC₆H₂CHNHCH₂Ph)] in which the organic ligand is bound to the metal through carbon atoms only. The last named isomer is directly analogous to the known o-phenylene compound [Os₃H₂(CO)₉(C₆H₄)]. The structures of these compounds are discussed on the basis of ¹H n.m r. and i.r. data and the consequences of replacing PhCH₂ by the asymmetric PhCHMe group are described.