Seven-Coordinate Titanium and Vanadium Carbonyls: Synthesis and X-ray Crystal Structures of [f-BUSi(CH2PMe2)3]TI(CO)4and [f-BuSi(CH2PMe2)3]V(CO)3H

Thomas G. Gardner, Gregory S. Girolami

Research output: Contribution to journalArticlepeer-review

Abstract

Reductive carbonylation of the tripod phosphine complexes [£-BuSi(CH2PMe2)3]MCl3(thf), where M is Ti or V and thf is tetrahydrofuran, with sodium naphthalenide in thf under carbon monoxide gives the titanium(O) carbonyl [£-BuSi(CH2PMe2)3]Ti(CO)4>1, and the vanadium(I) hydride [t-BuSi-(CH2PMe2)3]V(CO)3H, 2. X-ray crystallographic studies of these two compounds reveal seven-coordinate 4:3 piano stool geometries, with slightly different orientations of the fourfold and threefold faces; the titanium and vanadium structures may also be described in terms of a face-capped trigonal prism and a face-capped octahedron, respectively. Important structural parameters are as follows: Ti-CO = 1.98 (1), 2.00 (1) A; Ti-P = 2.612 (3), 2.632 (5) A; C-Ti-C(cis) = 69.8 (5), 71.7 (5)°; C-Ti-C(trans) = 109.9 (5)°; V-CO = 1.852 (9), 1.862 (7) A; V-P = 2.440 (2), 2.470 (2) A; C-V-C(cis) = 82.0 (3)°; C-V-C(trans) = 96.9 (3)°. The chelating nature of the phosphine ligand lends these complexes unusual kinetic and oxidative stability. Spectroscopic data for 1 and 2 are discussed: in particular, the large downfield1 2 3 4 5 6 7 8 9 10 11 12 13C NMR chemical shift and low CO stretching force constant in 1 indicate that there is unusually strong Ti —> CO ir back-donation.

Original languageEnglish (US)
Pages (from-to)2551-2556
Number of pages6
JournalOrganometallics
Volume6
Issue number12
DOIs
StatePublished - Dec 1 1987

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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