Synthesis, Structural Characterization and Photophysical Properties of Palladium and Platinum(II) Complexes Containing 7,8-Benzoquinolinate and various Phosphine Ligands

Resumen

A series of mononuclear cyclometalated benzo[h]quinolinate platinum and palladiurn(II) complexes with phosphine ligands, namely, [M(bzq)CIL] (L = PPh 2H, Pt 1, Pd 2; PPh 2C=CPh, Pt 3, Pd 4), [Pt(bzq)(PPh 2H)(PPh 2C=CPh)]CIO 4 5, [Pt(bzq)(PPh 2C(Ph)=C(H)PPh 2)]CIO 4 6, and [Pt(bzq)(C=CPh)(PPh 2C=CPh)] (7a,7b), were synthesized. The X-ray crystal structures of 1, 6·CH 3COCH 3·1/ 2CH 3(CH 2) 4CH 3, and 7b·CH 3COCH 3 have been determined. In 1, the metalated carbon atom and the P atom are mutually cis, whereas in 7b they are trans located. For complex 6, C and N are crystallographically indistinguishable. Reaction of [Pt(bzq)(μ-PPh 2)] 2 with PPh 2H and excess of NEt 3 leads to the phosphide-bridge platinum dimer [Pt(bzq)(μ-PPh 2)] 2 8 (X-ray). Moderate π-π intermolecular interactions and no evident Pt-Pt interactions are found in 1, 7b, and in 8. All of the complexes exhibit absorption bands at high energy due to the intraligand transitions ( 1IL π → π*) and absorptions at lower energy which are attributed to MLCT (5d) π → π*(C ΛN) transition. Platinum complexes show strong luminescence in both solid state and frozen solutions. The influence of the coligands on the photophysics of the platinum complexes has been examined by absorption and emission spectroscopy. © 2005 American Chemical Society.