TUNGSTEN CARBYNE COMPLEXES CONTAINING 1,1'-BIS(DIPHENYLPHOSPHINO)FERROCENE (DPPF) - REVERSE RELATIONSHIP BETWEEN NMR CHEMICAL-SHIFTS OF THECARBYNE C-13 AND THE W-183 NUCLEI AND MOLECULAR-STRUCTURE OF WCL(CO)2(DPPF)(CPH)

The Fischer-type carbyne complexes containing 1,1'-bis(diphenylphosphi no)ferrocene (dppf), WX(CO)2(dppf) (CR) [X = Cl, R = Me, Ph, thienyl, furyl, and ferrocenyl; X = Br; R = ferrocenyl], were synthesized. In t hese complexes, an increase in the W-183 and a decrease in the carbyne C-13 chemical shifts with increasing pi-donating ability of the carby ne substituents were observed. The ferrocenyl-substituted derivate sho wed the more enhanced redox potential compared with the corresponding carbonyl analog. The structure of WCl(CO)2(dppf)(CPh) has been determi ned by the single-crystal X-ray diffraction method. The crystal is mon oclinic with space group P2(1)/n, and the cell constants are a = 15.56 5(3) angstrom, b = 21.493(4) angstrom, c = 11.167(2) angstrom, beta = 92.45(1)degrees, and Z = 4. The structure has been refined to a final R value of 0.052. The coordination geometry around the W atom is octah edral with a cis chelation of dppf. The W-C bond distance [1.82(1) ang strom] is in the normal range. The Cp rings of the dppf ligand in the complex take a staggered conformation, but all the C atoms in each rin g are almost coplanar.