US Patent 7294729 Bis-chelating ligand and use thereof in carbonylation processes

A novel bis-chelating composition characterized by formula I: wherein M is a Group VB element; R1 and R2 are each independently selected from hydrogen and monovalent hydrocarbyl radicals; or R1 and R2 are bonded together to form a diradical; or one of R1 or R2 is hydrogen or a monovalent hydrocarbyl radical, while the other of R1 or R2 is a hydrocarbyl radical bonded to an atom in Ar; wherein Ar is selected from 1,2-arylenes; Q is selected from 1,2-arylenes, 2,2′-bisarylenes and alkyl diradicals; and W is selected from II, III, IV, or V: wherein M is as defined hereinbefore; each R is independently selected from hydrogen and monovalent hydrocarbyl radicals; X is selected from alkyl and aryl diradicals; Ar1 and Ar2 are each independently selected from 1,2-arylenes;Ar3 and Ar4 are each independently selected from monovalent aryl radicals; and n in formula IV is 0 or 1. The composition finds utility as a ligand in catalysts for carbonylation processes