The d4 halide complexes [MX(CO)(eta-RC[triple bond, length as m-dash]CR)Tp'] {X=F, Cl, Br or I; R=Me or Ph; M=Mo or W; Tp'=hydrotris(3,5-dimethylpyrazolyl)borate} undergo one-electron oxidation to the d3 monocations [MX(CO)(eta-RC[triple bond, length as m-dash]CR)Tp']+, isolable for M=W, R=Me. X-Ray structural studies on the redox pairs [WX(CO)(eta-MeC[triple bond, length as m-dash]CMe)Tp']z (X=Cl and Br, z=0 and 1), the ESR spectra of the cations [WX(CO)(eta-RC[triple bond, length as m-dash]CR)Tp']+ (X=F, Cl, Br or I; R=Me or Ph), and DFT calculations on [WX(CO)(eta-MeC[triple bond, length as m-dash]CMe)Tp']z (X=F, Cl, Br and I; z=0 and 1) are consistent with electron removal from a HOMO (of the d4 complexes) which is pi-antibonding with respect to the W-X bond, pi-bonding with respect to the W-C(O) bond, and delta-bonding with respect to the W-Calkyne bonds. The dependence of both oxidation potential and nu(CO) for [MX(CO)(eta-RC[triple bond, length as m-dash]CR)Tp'] shows an inverse halide order which is consistent with an ionic component to the M-X bond; the small size of fluorine and its closeness to the metal centre leads to the highest energy HOMO and the lowest oxidation potential. In the cations [MX(CO)(eta-RC[triple bond, length as m-dash]CR)Tp']+ electronegativity effects become more important, leading to a conventional order for Cl, Br and I. However, high M-F pi-donation is still facilitated by the short M-F distance.

Preparation of commercially pure titanium metal powder by electrolysis of K:~TiF~ in molten NaCI is described. The process is carried out under an inert atmosphere in an all-graphite cell. Operating conditions of the electrolysis and their effect upon the metal so produced are discussed. Preparation of the K2TiF~ and the electrolytic procedure are completely described. The process is capable of producing metal of high purity which may be consolidated and fabricated by standard techniques as applied to metal powders. The metal is recovered by aqueous washing techniques. It may be prepared either as coarsely crystalline metal or as coarse thin metal flakes.

X-Ray structural and EPR spectroscopic studies of the redox-related pairs [WX(CO)(MeC•CMe)TpA] z (X = F, Cl, Br and I; z = 0 and 1) [TpA = hydrotris(3,5-dimethylpyrazolyl)borate] are consistent with the HOMO of the d 4 (z = 0) species being p-bonding with respect to the W-CO bond, p-antibonding with respect to the W-X bond, and d-bonding with respect to the W-alkyne bond.