Cyclometallated complexes of palladium(II) with 1-methyl-2-phenylimidazole and tertiary diphosphines. Crystal and molecular structure of [Pd[o-C6H4C=NC(H)=C(H)NMe](Ph2PCH(Me)PPh2-P,P)][PF6]

Abstract Treatment of Pd(AcO) 2 with 1-methyl-2-phenylimidazole, and subsequent treatment with sodium chloride or sodium bromide gave the corresponding halide-bridged cyclometallated complexes [Pd o -C 6 H 4 C=NC(H)=C(H)NMe( μ -X)] 2 ( 2 , X = Cl; 3 , X = Br). Complexes 2 and 3 react with tertiary diphosphines in a 1:1 molar ratio to give dinuclear cyclometallated compounds with bridging diphosphine and halogen ligands [Pd o -C 6 H 4 C=NC(H)=C(H)NMe( μ -L-L)( μ -X)]X ( 4–9 ) or with only bridging diphosphine ligands [Pd o -C 6 H 4 C=NC(H)=C(H)NMe( μ -L-L)(X) 2 ] ( 10–17 ), [X = Cl, Br; L-L = Ph 2 PCH 2 PPh 2 (dppm), Ph 2 PC(=CH 2 )PPh 2 (vdpp), Ph 2 PCH(CH 3 )PPh 2 (1,1-dppe), trans -Ph 2 P(CH=CH)PPh 2 ( trans -dppe), Ph 2 P(CH 2 ) 2 PPh 2 (dppe), Ph 2 P(CH 2 ) 3 PPh 2 (dppp), Ph 2 P(CH 2 ) 4 PPh 2 (dppb), as appropriate]. When the reaction is carried out in a 1:2 molar ratio and in the presence of NH 4 PF 6 or NaClO 4 , mononuclear cyclometallated compounds with a chelating diphosphine ligand are obtained [Pd o -C 6 H 4 C=NC(H)=C(H)NMe(L-L-P,P)][Y] ( 18–27 ) [Y = PF 6 , ClO 4 ; L-L = Ph 2 PCH 2 PPh 2 (dppm), Ph 2 PC(=CH 2 )PPh 2 (vdpp), Ph 2 PCH(CH 3 )PPh 2 (1,1-dppe), Ph 2 PN(CH 3 )PPh 2 (dppma), cis -Ph 2 P(CH=CH)PPh 2 ( cis -dppe), Ph 2 P(CH 2 ) 2 PPh 2 (dppe), Ph 2 P(CH 2 )PPh 2 (dppp), Ph 2 P(CH 2 ) 4 PPh 2 (dppb)]. Compounds 18–22 and 25–27 could also be obtained by reaction of complexes 4–17 with the appropriate diphosphine and NH 4 PF 6 or NaClO 4 . The diphosphines dppma and cis -dppe failed to behave as bridging ligands and only gave mononuclear compounds. The complexes were characterized by their elemental analysis (C, H, N) and by IR and 31 P- 1 H and 1 H NMR data. The X-ray crystal structure of complex 22 is described.