Inorganic Chemistry, Vol.40, No.18, 4583-4587, 2001
Mono- and dinuclear five-coordinate cyclometalated palladium(II) compounds
Reaction of cyclometalated halide-bridged Pd(II) complexes 1-4 with the tertiary triphosphine ligand (Ph2PCH2CH2)(2)PPh (triphos) yielded complexes [{(Ph2PCH2CH2)(2)PPh-P,P,P}Pd{N(Cy)=(H)C}C6H2{C(H)=N(Cy)}Pd{(Ph2PCH2CH2)(2)PPh-P,P,P}][ClO4](2)5, [Pd{C6H4-N=NC6H5}{(Ph2PCH2CH2)(2)PPh-P,P,P}][ClO4] 6, and [Pd{RC6H3C(H)=NCy}{(Ph2PCH2CH2)(2)PPh-P,P,P}][ClO4] (7; R = 4-CHO, 8; 3-CHO). Spectroscopic and analytic data suggest five-coordination on the palladium atom, which, for complexes 5, 6, and 7, was confirmed by X-ray crystallography. The geometry around palladium may be view as a distorted trigonal bipyramid, with the palladium, nitrogen, and terminal phosphorus atoms in the equatorial plane. Compound 5 is the first doubly cyclometalated palladium(II) compound with two pentacoordinated metal centers. The structure of 6 comprises two discrete cations with slightly different geometries, showing the importance of crystal packing forces in order to determine the coordination arrangement.