The d2/d3 alkyne redox pair [WF2(PhCCPh)Tp′]z (z = +1 or 0): missing links in a ‘redox family tree’

Abstract

The d2/d3 redox pair [WF2(PhC identical to CPh)Tp']z [z = +1 or 0, Tp' = hydrotris(3,5-dimethylpyrazolyl)borate] is the missing link in a 'redox family tree' relating the d6 tricarbonyls [M(CO)3L]- to the d2 trihalides [MX3L] (M = Mo or W, L = Cp or Tp') by a series of stepwise reactions involving sequential one-electron oxidation followed by ligand substitution.

The d4/d3redox pairs [MX(CO)(η-RCCR)Tp′]z(z = 0 and 1): structural consequences of electron transfer and implications for the inverse halide order

“…Indeed, the optical isomers of [WI(CO)(g-MeC≡CMe)Tp ] have been separated. 10 In addition, the 13 C chemical shifts for the metal-bound alkyne carbons (two for each complex), at 194-219 ppm, are consistent with four-electron alkynes. 9 Each of the but-2-yne complexes [MX(CO)(g-MeC≡CMe)Tp ] (1-5 and 10-14) shows two sharp singlets in both the 1 H NMR (in the range 2.71-3.39 ppm) and 13 C{ 1 H} NMR spectra (between 18 and 23 ppm) for the alkyne methyl substituents, suggesting that no alkyne rotation occurs at ambient temperature; variable-temperature NMR spectroscopic studies also showed a high barrier to alkyne rotation for [WI(CO)(g-PhC≡CH)Tp ]…”

“…The IR spectra were recorded on a Nicolet 5ZDX FT spectrometer or a Perkin Elmer Spectrum One FT-IR spectrometer fitted with a Perkin Elmer ZnSe Universal ATR sampling accessory. Proton, 13 C{ 1 H} and 19 F NMR spectra were recorded on JEOL GX270, Eclipse 300 or GX400 spectrometers with SiMe 4 or CCl 3 F (for 19 F) as internal standards. All spectrometers operated in the Fourier transform mode, with field stability maintained by an external lock system.…”

“…The complex [WI(CO)(g-MeC≡Me)Tp ] has been made previously 4 but a general method involving the reaction of a School of Chemistry, University of Bristol, Bristol, UK BS8 1TS E-mail: neil.connelly@bristol.ac.uk; Fax: 0117 929 0509; Tel: 0117 928 8162 b Department of Chemistry, Brown University, Rhode Island, RI, 02912, USA † Electronic supplementary information (ESI) available: Table S1: Proton and 13 These complexes were characterised by elemental analysis, IR spectroscopy and cyclic voltammetry (Table 1), 1 H and 13 C NMR spectroscopy and, in the cases of [WCl(CO)(g-MeC≡CMe)Tp ] 11, [WBr(CO)(g-MeC≡CMe)Tp ] 12 and [W(NCS)(CO)(g-Me-C≡CMe)Tp ] 14, by X-ray crystallography (see below). In CH 2 Cl 2 the IR spectrum of each complex shows one m(CO) absorption in the range 1875-1940 cm −1 .…”

“…As will be described elsewhere in more detail, these products are of the form [WFX(g-PhC≡CPh)Tp ] +/0 (X = F, Cl or Br). 13 Other fluoride complexes have been obtained similarly by the abstraction of F − from…”

One-Electron Reduction of Molybdenum η2(4e)-Alkyne Complexes as a Pathway to the η2(3e) Vinyl Ligand

“…Insight into the structure and bonding of metal alkyne complexes has also been gained by systematic study of their redox properties. In particular, the ramifications of changes in both formal d-electron count and the number of electrons donated by the alkyne ligands across a series of complexes have been elegantly probed. − These studies demonstrate that alkyne ligands are extremely flexible in the bonding modes that they can adopt within the coordination sphere of metals: a property that may enhance their reactivity . As well as providing insight into the electronic structure of metal alkyne complexes, one-electron-transfer reactions may also initiate some interesting intramolecular ligand couplings.…”