Peripherally-metallated porphyrins: synthesis and spectra of meso-eta(1)-palladio- and platinioporphyrins and the crystal structures of cis-{PtBr[l 0,20-diphenylporphyrinatonickel(II)-5-yl](PPh3)(2)} and trans-{PtBr[10,20-diphenylporphyrin-5-yl](PPh3

摘要

A series of meso-eta(1)-palladio(II)- and platinio(II)porphyrins containing either monodentate Group 15 ligands (PPh3, AsPh3) or chelating diphosphines (dppe, dppp, dppf) has been prepared by oxidative addition of mono- and dibromo derivatives of 5,15-diphenylporphyrin (H2DPP) to Pd(0) and Pt(0) precursors. The products were characterized by their H-1- and P-31-NMR, visible absorption, and mass spectra and the X-ray crystal structures of trans-[PtBr(H2DPP)(PPh3)(2)] (14) (as a 0.25CH(2)Cl(2) solvate) and cis-[PtBr(NiDPP)(PPh3)(2)] (15) were determined. The structures show approximately square planar geometry about the Pt atoms, although there are distortions due to crowding of the PPh3 ligands in 15. The NiDPP ring in 15 suffers ruffling typical of peripherally-crowded Ni(II) porphyrins, the pairs of opposite meso carbons being displaced alternately > +/- 0.4 Angstrom out of the C20N4 mean plane The conformations of the phenyl groups of the PPh3 ligands indicate the presence of non-covalent phenyl-porphyrin pi-pi interactions. These derivatives are the first isolated examples of peripheral organometallic porphyrins with direct transition metal to porphyrin sigma-bonds, and they represent a new class of superstructured porphyrins with one or both faces of the macrocycle heavily shielded by the phenyl groups on the auxiliary ligands. (C) 2000 Elsevier Science S.A. All rights reserved. [References: 32]