PREPARATION OF CARBONYL PHOSPHINE RHODIUM COMPLEXES WITH DITHIOLATE BRIDGES - APPLICATION AS CATALYST PRECURSORS IN THE HYDROFORMYLATION OF 1-HEXENE

The reactivity of [Rh-2(mu-S(CH2)(n)S)(CO)(4)] (n = 2, 3 or 4) have been investigated and mixed carbonyl phosphine complexes [Rh-2(mu-S(CH2)(n)S)(Co)(2)(PR(3))(2)](x) (R = C6H5, C6H11, O-2-(t)BuC(6)H(4); n = 2, 3 and 4; x = 1 or 2) have been prepared and studied by IR, P-31-{H-1} NMR and FAB mass spectrometry. Dinuclear complexes [Rh-2(mu-S(CH2)(2)S)(CO)(2)(PR(3))(2)] (R = C6H5, C6H11, O-2-(t)BuC(6)H(4)) and tetranuclear [{Rh-2(mu-S(CH2)(4)S)(CO)(2){P(O-2-(t)BuC(6)H(4))(3)}(2)}(2)] formulations are proposed on the basis of FAB mass spectrometry. The complexes [Rh-2(mu-S(CH2)(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.