Linkage Isomerization Equilibria in (Chloranilato)palladium(II) Complexes with Amine Ligands. Crystal Structure of (Chloranilato)bis(acetonitrile)palladium(II)

Andrew J. Bessire, Bruce R. Whittlesey, Robert A. Holwerda

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6 Scopus citations

Abstract

A series of (chloranilato)palladium(II) complexes of the type [Pd(CA)(amine)2] have been prepared to probe inductive effects on linkage isomerization between dicarbanion (C-CA) and quinonoid (π-CA) forms of the bidentate chloranilate ligand. Electronic, infrared, and 1H NMR spectra of [Pd(CA)(py-4-X)2] species (X = H, C(CH3)3, COOH, C(O)NH2, N(CH3)2, OH, CN, NH2) show an unexpected mixture of C-CA and π-CA isomers whose distribution is insensitive to variations in the X substituent. Evidence is presented that Pd(CA) complexes with py-4-X ligands have variable structures which depend strongly on the solvent employed in their synthesis. The first high-resolution crystal structure of a C-bonded CA2− complex is reported. [Pd(C-CA)(CH3CN)2] crystallizes in the triclinic P1 space group with a = 8.681(2) Å, b = 11.371(2) Å, c = 13.997(3) Å, a = 91.32(1)°, ß = 97.28(1)°, γ = 96.129(5)°, and V = 1361.5(7) Å3; Z = 4. Chloranilate ligates Pd(II) through both C-Cl carbon atoms, with identical Pd-C and Pd-N bond lengths of 2.09 and 2.07 Å, respectively. Bond angles of the two carbon-donor atoms span the interval from 90.8 to 121.7°, with Pd-C-C and all other angles around the coordinated C atoms falling in the ranges 90.8-95.6 and 112.5-121.7°, respectively. The chloranilate ligand adopts a boat conformation (132.7° bend angle), and Pd(II) has a distorted square-planar coordination geometry characterized by average C-Pd-C, C-Pd-N, and N-Pd-N angles of 77.5, 95.1, and 92.4°, respectively.

Original languageEnglish
Pages (from-to)622-627
Number of pages6
JournalInorganic Chemistry
Volume34
Issue number3
DOIs
StatePublished - Oct 1 1995

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