WEAK PT-H-C INTERACTIONS - EXTENSIONS TO 8-METHYLQUINOLINE, BENZOQUINOLINE, AND A TETRALONE SCHIFF-BASE - X-RAY CRYSTAL-STRUCTURE OF TRANS-PTCL2(BENZOQUINOLINE)(PET3)

A series of platinum complexes containing coordinated 8-methylquinoline, benzoquinoline, the cyclohexylamine Schiff base of tetraione, and (among others) quinoline-8-carbaldehyde have been prepared and studied by 1H and 13C NMR methods. All of these complexes reveal weak Pt-H-C interactions to remote protons to very different extents, with J(Pt, H) values ranging from 5 to 21 Hz. There is some correlation to the 13C data in that complexes with small J(Pt, H) values show no platinum spin-spin coupling to 13C whereas compounds with ca. 20-Hz couplings show J(Pt, C) values of 63 and 66 Hz. Steric boundary conditions for this type of interaction as well as the potential usefulness of chemical shifts in recognizing this interaction are discussed. The molecular structure for trans-PtCl2(benzoquinoline)(PEt3) has been determined by X-ray diffraction. The molecule crystallizes in the space group [formula omitted], with a = 7.8216 (8) Å, b = 7.8607 (6) Å, c = 17.0376 (13) Å, a = 94.30 (1)°, μ = 98.50 (2)°, γ = 100.63 (1)°, and Z = 2. The H(10)-Pt separation of ca. 2.5 Å is consistent with the weak bonding interactions described by the NMR experiments. © 1990, American Chemical Society. All rights reserved.