Synthesis and structures of Pd2M2 (M = Cu, Au) and Pd2M (M = Cu, Ag) mixed-metal complexes supported by NPPN tetradentate ligands

Abstract Reactions of [PdCl(Me)(cod)] with two NPPN mixed-donor tetradentate ligands, meso -2-pyridylCH 2 (Ph)P(CH 2 ) 2 P(Ph)CH 2 -2-pyridyl ( meso -picppe) and rac -2-pyridylCH 2 (Ph)P(CH 2 ) 4 P(Ph)CH 2 -2-pyridyl ( rac -picppb), afforded dinuclear palladium complexes [(PdCl(Me)) 2 ( meso -picppe)] ( 1 ) and [(PdCl(Me)) 2 ( rac -picppb)] ( 2 ), which were further converted with 2,6-xylyl isocyanide (XylNC) to [(PdCl(C( NXyl)Me)) 2 ( meso -picppe)] ( 3 ) and [(PdCl(C( NXyl)Me)) 2 ( rac -picppb)] ( 4 ) through insertion of XylNC into the Pd–Me bonds. Complexes 3 and 4 possess two imidoyl moieties which are of potential donors and readily capture d 10 group 11 metal ions depending on their stereostructures of the NPPN ligands. Reactions of 3 with CuCl or AuCl(tht) afforded Pd 2 M 2 mixed-metal tetranuclear complexes [(PdCl(C( NXyl)Me)(MCl)) 2 ( meso -picppe)] (M = Cu ( 5a ), Au ( 5b )), where each imidoyl moiety captures a MCl fragment in a C i symmetrical fashion. Similar reactions of 4 with [Cu(MeCN) 4 ]BF 4 or AgBF 4 resulted in Pd 2 M trinuclear complexes [(PdCl(C( NXyl)Me) 2 M( rac -picppb)]BF 4 (M = Cu ( 6a ), Ag ( 6b )), in which two imino groups chelate a M I ion with a pseudo C 2 symmetrical structure.