NUCLEOPHILIC-ATTACK BY 2-PYRIDYLPALLADIUM(II) AND PLATINUM(II) COMPLEXES ON THE ORGANIC CHLORIDES CLCH2R (R = COME, CN, PH, CL)

The 2-pyridyl complexes trans-[MCl(C5H4N-C2)(PPh3)2] (M = Pd, 1a; M = Pt, 1b), [MCl(C5H4N-C2)(dppe)] (M = Pd, 2a; M = Pt, 2b) and [M(dmtc)(C5H4N-C2)(PPh3)] (M = Pd, 3a; M = Pt, 3b) react with the chlorides ClCH2R (R = COMe, CN, Ph) to give cationic products containing the 2-pyridylium ligands (1-CH2R)C5H4N-C2. The rate of nucleophilic displacement of the chloride ion from ClCH2R depends on the central metal (Pt > Pd), on the coordination geometry (1 < 2 approximately 3) and on the substituent R (COMe > CN > Ph for the reactions with 3b). Like 1b and 2b, complex 3b also reacts with dichloromethane to give [Pt(dmtc){(1-CH2Cl)C5H4N-C2}(PPh3)]+. The reaction of the binuclear compound [{PdCl(mu-C5H4N-C2,N)(PPh3)}2] with chloroacetone in the presence of chloride ion yields the zwitterionic derivative cis-[PdCl2{(1-CH2COMe)C5H4N-C2}(PPh3)]. The cationic products have been isolated and characterized as perchlorate salts.