USE OF MICHAEL ADDITIONS TO (PH2P)2C-2=CH2 COMPLEXES TO PREPARE THIOPHENE-FUNCTIONALIZED AND PYRROLE-FUNCTIONALIZED METAL PHOSPHINE COMPLEXES

The complex [Pd(O2CMe)2(vdpp)] la [vdpp = (Ph2P)2C=CH2] undergoes nucleophilic addition at the double bond with primary alcohols to afford [Pd(O2CMe)2{(Ph2P)2CHCH2OR}] 2 [R = Me, Et, CH2CH2C4H3S-3 or CH2C6H3(OMe)2-3,4]. These were not isolated pure, but metathesis with NaI gave the corresponding diiodides 3, which were isolated, and have been fully characterised by microanalysis and infrared and NMR (H-1 and P-31-{H-1}) spectroscopies. By using 2- (3-thienyl)ethanol as the nucleophile, the complex [PdI2{(Ph2P)2CHCH2OCH2CH2C4H3S-3)] 3c was obtained, and its electrochemistry examined. The reactivity of the double bond in 1a towards other potential weak nucleophiles has been examined. In particular, pyrrole underwent electrophilic addition with la to give, after work-up with NaI, [PdI2{(Ph2P)2CHCH2C4H3NH}]4b. Proton NMR spectroscopy established that 4b was a mixture of 2- and 3-pyrrole isomers (ca. 3: 1). The complexes [MCl2(vdpp)] (M = Pd 1c or Pt 1d) were less reactive, but underwent addition with alcohols in the presence of NEt3 as catalyst to afford [MCl2{(Ph2P)2CHCH2OR}] (M = Pd 5 or Pt 6, R = Et or CH2CH2C4H3S-3). The complex [Pt(vdpp)2][PF6]2 7 has been prepared from [PtCl2(PhCN)2], vdpp and AgPF6 in dichloromethane-acetonitrile. Details of the reaction of 7 with 2- (3-thienyl)ethanol are given. The crystal structure of 3c has been determined.