Rearrangements of the unsaturated ligand 1,1-bis(diphenylphosphinomethyl)ethene and its chalcogenides and group VI metal carbonyl complexes

Abstract

In contrast to the behaviour of other unsaturated organophosphines, treatment of the new ligand (Ph 2PCH 2) 2CCH 2 with Ph 2PH in the presence of KOBu t does not result in addition to the double bond; instead, an allylic rearrangement occurs to give cis and trans Ph 2PCHC(CH 3)CH 2PPh 2 in a 3:7 ratio. In the case of (Ph 2P(E)CH 2) 2CCH 2 [E = S, Se] only the trans isomer is obtained from this reaction, while under similar conditions (CO) 4M(Ph 2PCH 2) 2CCH 2 [M = Cr, Mo, W] yields only a cis product in which the two phosphorus atoms remain chelated. The products of these and related reactions are characterized by elemental analysis and 13C and 31P NMR spectroscopy.