Preparation of carbonyl phosphine rhodium complexes with dithiolate bridges. Application as catalyst precursors in the hydroformylation of 1-hexene

Abstract

The reactivity of [Rh 2(μ-S(CH 2) n S)(CO) 4] ( n = 2, 3 or 4) have been investigated and mixed carbonyl phosphine complexes [Rh 2(μ-S(CH 2) n S)(CO) 2(PR 3) 2] x (R = C 6H 5, C 6H 11, O-2- tBuC 6H 4; n = 2, 3 and 4; x = 1 or 2) have been prepared and studied by IR, 31P- 1H NMR and FAB mass spectrometry. Dinuclear complexes [Rh 2(μ-S(CH 2) 2S)(CO) 2(PR 3) 2] (R = C 6H 5, C 6H 11, O-2- tBuC 6H 4) and tetranuclear [{Rh 2(μ-S(CH 2) 4S)(CO) 2}P(O-2- tBuC 6H 4) 3{ 2} 2] formulations are proposed on the basis of FAB mass spectrometry. The complexes [Rh 2(μ-S(CH 2) n S)(COD) 2] ( n = 2, 3 or 4; COD = 1,5-cyclooctadiene) have been used as catalyst precursors for 1-hexene hydroformylation. The influence of different dithiolates and phosphines on the catalytic activity and the selectivity have been explored.