Hydrogenation and Coupling of Vinyl Groups in the Coordination Sphere of a Divalent Ruthenium Complex Formed by an Olefinic Tertiary Phosphine

Abstract

The complex RuCl2(CO)2(SP)2 (I) (SP = o-styryldiphenylphosphine, o-CH2=CHC6H4PPh2), which contains rnoncdentate P-bonded SP, reacts in boiling 2-methoxyethanol to give three new octahedral complexes of ruthenium(II), the structures of which have been deduced from 1H and 31P NMR spectroscopic studies and in one case by a single-crystal X-ray diffraction study. The major product, [formula omitted] (II), contains one bidentate SP moiety and a five-membered chelate ruthenium-carbon σ-bonded ring formed by addition of one hydrogen atom to coordinated SP. and 31P NMR studies show that complex II in solution consists of an equilibrium mixture of two isomeric forms. Similar results are obtained for the derived dicarbonyl cation [formula omitted] (HI). In each, case, interconversion of the isomers was observed by NMR above ambient temperature and the rate of exchange was estimated from the spectra obtained. The isomerism is attributed to different orientations of the coordinated vinyl group. The second complex is [formula omitted] (IV), in which the two vinyl groups of I have incorporated one hydrogen atom and coupled to give a tridentate PCP grouping containing fused five-and seven-membered chelate rings. The third complex, [formula omitted] (VII), which is formed in very low yield, is formally derived from II by oxidation of the methyl group to an aldehyde function. Carbonylation of II for I hr gives a mixture of IV with an isomer V,[formula omitted], which differs from IV in that it contains two fused six-membered rings; i.e., the ruthenium-carbon a bond is formed at the 2 instead of the 1 position of the butane chain. V can be prepared in a pure state by addition of hydrogen chloride to the ruthenium(O).Complex of 1,3-bisjo-(diphenylphosphinojphenylj-trans-1-butene,Ru(CO)2[o-Ph2PC6H4CH=CHCH(CH3)C6H4PPh2-o] (Vi), V isomerizes to IV in boiling 2-methoxyethanol, possibly via an olefin hydride intermediate. Under forcing conditions I reacts with 2-methoxyethanol to give a mixture of IV and a complex of o-ethylphenyldiphenylphosphine, RuCl2(CO)2(o-Ph2PC6H4C2H5)2 (XV). The formation of II, IV, and XV is thought to involve reaction of I with 2-methoxyethanol to give intermediate ruthenium(II) hydride complexes. Show more