Rhodium complexes with dioximes as catalysts of hydroformylation and hydrogenation of 1-hexene

Abstract

Rhodium(II) complexes with dioximes [Rh(Hdmg) 2(PPh 3)] 2 [ I] (Hdmg=monoanion of dimethylglyoxime) and [Rh(Hdmg)(ClZndmg)(PPh 3)] 2 [ II] catalyse hydroformylation and hydrogenation reactions of 1-hexene at 1 MPa CO/H 2 and 0.5 MPa H 2 at 353 K, respectively. Hydroformylation with complex [ I] produces 94% of aldehydes ( n/ iso=2.2) and 6% 2-hexene whereas the second catalyst [ II] gives ca. 40% of aldehydes ( n/ iso=2.1) and 60% of 2-hexene. Corresponding Rh(III) complexes are inactive in hydroformylation except of RhH(Hdmg) 2(PPh 3) [ III], which shows activity similar to [ I]. Complexes [Rh(Hdmg) 2(PPh 3)] 2 [ I], [Rh(Hdmg)(ClZndmg)(PPh 3)] 2 [ II], RhH(Hdmg) 2(PPh 3) [ III] and [Rh(Hdmg) 2(PPh 3) 2]ClO 4 [ V] catalyse 1-hexene hydrogenation with an average TON ca. 18 cycles/mol [Rh]×min. Complex [ II] has also been found to catalyse hydrogenation of cyclohexene, 1,3-cyclohexadiene and styrene.