Homonuclear Pd and pt and Heteronuclear Pd_Au and Pt-Au Complexes of a Tripod Triphosphine Ligand: Synthesis, Characterization and Reactions with Molecules of Biological Relevance

摘要

Complexes of the type Pd(tripod)X2 [tripod = MeC(CH2PPh2)3; X= Cl (1), Br (2), I (3)] and Pt(tripod)X2 [X = Cl (4), Br (5), I (6)] have been synthesized. In these complexes tripod acts as a bidentate chelating ligand. The unco- ordinated phosphorus atom can bind to AUI to form the bimetallic complexes PdAu(tripod)X3 [X = Cl (7), Br (8), I (9)] and PtAu(tripod)X3 [X = Cl (10), Br (11), I (12)]. Complexes (1)-(12) have been characterized by microanaly- sis, f.a.b. mass spectrometry, i.r. spectroscopy, 31p and 195pt n.m.r. spectroscopies, and conductivity measurements. The structures of complexes ( I ), (4) and ( 11 ), as well as that of the unusual complex CI2Pt(tripod)AuBro.5Clo.5 ( 13), 'J isolated from reaction of Pt(tripod)Br2 (5), and [Au(thiodiglycol)Cl], have been determined. All complexes show square-planar geometry for Pdll or ptll and linear geometry for AUI. The X-ray crystal structure of(l) showed partial oxidation of the dangling phosphorus of the ligand in 50% of the molecule distributed randomly over the lattice. Reactions of complex (4), Pt(tripod)CI2, with the tripeptide glutathione (GSH) showed the formation of [Pt2(tripod)2(GS-j.!-S)2]2+ (15a). No reaction with N-acetyl-L-methionine (AcMet) or guanosine 5 '-monophosphate (5'-GMP) was observed. Reactions of [Pt(tripod-O)(ONO2)2] (14) with GSH resulted in the formation of [Pt2(tripod-O)2(GS-j.!-S)2]2+ (15b). Displacement of the S-containing molecules by 5 '-GMP in the presence of AUI, via Pt-S bond cleavage, was observed for complex (15b). PtAu(tripod)CI3 (10) reacted with GSH, with initial attack on the AUI centre.