(π-Acetylene) (σ-vinyl) Transition Metal Complex. The Structure of (σ-Dicyanovinyl) (carbonyl) (π-dicyanoacetylene)bis(triphenylphosphine)iridium(I), Ir(-C(CN) ═ CHCN) (CO) (NCC ≡ CCN) (P(C6H5)3)2

Richard M. Kirchner, James A Ibers

Research output: Contribution to journalArticle

33 Scopus citations

Abstract

The structure of (σ-dicyanovinyl)(carbonyl)(π-dicyanoacetylene)bis(triphenylphosphine)iridium(I), Ir(-C(CN)═CHCN)(CO)(NCC≡CCN)P(C6H5)3)2, has been determined from three-dimensional X-ray data collected by counter methods. The pale pink compound crystallizes in space group C1-P[formula-omitted] of the triclinic system with two molecules in a reduced unit cell of dimensions a = 12.092 (3) Åk,b= 15.987 (4) Å, c = 11.575 (4) Å, α = 93.89 (1)°, β = 115.25 (2)°, and γ = 99.75 (1)°. The observed and calculated densities are 1.46 (2) and 1.51 g cm-8, respectively. Full-matrix least-squares refinement gave a final value of the conventional R factor (on F) of 0.038 for the 2652 reflections having F2 > 3σ(F2). The structure consists of discrete monomers. The coordination geometry about the metal is distorted trigonal bipyramidal if the π-bonding dicyanoacetylene ligand is considered to be monodentate. The triphenylphosphine ligands occupy the apical coordination sites while the dicyanoacetylene, dicyanovinyl, and carbonyl ligands are in the basal plane. The dicyanoacetylene and dicyanovinyl C-C “triple” and “double” bonds are tipped with respect to the basal coordintion plane 3 (1) and 11 (1)°, respectively. Some important bond distances in Å are Ir-P(1), 2.375 (2); Ir-P(2), 2.382 (3); Ir-C(dicyanoacetylene), 2.07 (1), 2.10 (1); Ir-C(dicyanovinyl), 2.09 (1); and Ir-C(carbonyl), 1.89 (2), while the dicyanoacetylene and dicyanovinyl central C-C bonds are equal at 1.29 (2). The bonding of the dicyanoacetylene ligand is similar to that found for other π-bonding acetylenic groups, with a NC-C-C average bond angle of 140 (1)°. The σ-bonding dicyanovinyl C═C bond length and Ir-C═C bond angle of 135 (1)° agree with the values found for other σ-bonding vinyl groups. The dicyanovinyl ligand has the Ir and H atoms trans to each other.

Original languageEnglish (US)
Pages (from-to)1095-1101
Number of pages7
JournalJournal of the American Chemical Society
Volume95
Issue number4
DOIs
StatePublished - Feb 1 1973

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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