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The rates of reaction of Cr(CO) 5 with several solvents L(L = acetone, acetonitrile, benzene, diethyl ether, ethyl acetate and methanol) and of the decay of the Cr(CO) 5 L in CO-saturated cyclohexane solutions have been measured by both conventional and laser flash photolysis. The rate constants for formation and the stability constants of Cr(CO) 5 L have been deduced, and both sets of values are suggested as possible solvent parameters for organometallic reactions [e.g. for the catalytic oligomerisation of butadiene by dibutadieneiron monocarbonyl].

The preparation of a series of cis-[RuII(L–L)2(CO)L]n+ complexes [L–L-2,2′-bipyridyl (bipy), n= 1, L = H, Cl, or NCS; n= 2, L = H2O, MeCN, CO, pyridine (py), 4-vinylpyridine (vpy), or 4-methylpyridine (Mepy); L–L = 4,4′-dimethyl-2,2′-bipyridyl (Me2bipy), n= 1, L = H or Cl; n= 2, L = H2O or CO] is reported. The CO stretching frequency, the energy of the d–π* metal to ligand charge-transfer absorption bands, and the oxidation and reduction potentials of the complexes are found to depend markedly on the σ- and the π-donor abilities of the ligands. In complexes [Ru(L–L)2(CO)(H2O)]2+ and [Ru(L–L)2(CO)Cl]+ the water and Cl– ligands are thermally substitution labile. On u.v. irradiation all complexes except [Ru(L–L)2(CO)H]+ are efficiently decarbonylated.

Reaction of Li(CPhCMe2) with SnCl4 or CrCl3·3thf (thf = tetrahydrofuran) affords the isoleptic compounds Sn(CPhCMe2)4 or [Cr(CPhCMe2)4] respectively. The mode of formation and chemical properties are reported for the chromium species, and the structures of the new compounds, both of which have been determined by single-crystal X-ray analysis, are described.

Complexes [Ru(bipy)2H(L)]X (bipy = 2,2′-bipyridyl; L = CO or PPh3, X = PF6; L = AsPh3, X = ClO4) and [Ru(Me2bipy)H(CO)]PF6(Me2bipy = 4,4′-dimethyl-2,2′-bipyridyl) have been synthesised by the reaction of the corresponding [Ru(bipy)2Cl(L)]+ complex or [Ru(Me2bipy)Cl(CO)]+ respectively with sodium tetrahydroborate in aqueous ethanol. In dilute acid [Ru(bipy)2H(CO)]+ yields [Ru(bipy)2(OH2)(CO)]2+ and hydrogen gas. [Ru(bipy)2H(CO)]+ is relatively photostable compared with [Ru(bipy)2H(PPh3)]+. The phosphine and arsine complexes show, in general, an increased reactivity compared to the carbonyl complexes.