Unbridged homo and hetero dinuclear complexes of Group 6 and 8 metals: synthesis, characterization and comparison of X-ray crystallographic data

Several novel compounds of the type Cp/Cp*(CO)(3)M-M'(CO)(n) Cp/Cp* (M = Cr , Mo, W; M' = Ru, n = 2; M' = Mo, n = 3; Cp = C5H5, Cp* = C5Me5) were synth esized, characterized, their structures compared and preliminary reactivity studies were carried out. The main investigations were focused on the moly bdenum and ruthenium containing heterobimetallic compounds Cp(CO)(3)Mo-Ru(C O)(2)Cp (1) as well as Cp(CO)(3)Mo-Ru(CO)(2)Cp* (2) and Cp*(CO)(3)Mo-Ru(CO) (2)Cp (3), the latter two representing a 'mixed-metal mixed-ligand' type of complexes with the former (1) having identical ligands on both metal cores . For the first time comparison of properties of unbridged bimetallic compl exes with molybdenum and ruthenium metal cores was elaborated. The novel Cp (CO)(3)Mo-Mo(CO)(3)Cp* (4) consists of two identical metal cores and of 'mi xed' ligands. 4 was prepared by treating NaMo(CO)(3)Cp with Cp*Mo(CO)(3)Br (5) after a route for the synthesis of the latter was established. 1 reacte d with halides or AlCl3, respectively, under cleavage of the metal-metal bo nd to form Cp(CO)(n)MHal (M = Mo, n = 3; M = Ru, n = 2; Hal = Br, I, Cl) bu t was shown to be inert towards substrates such as CO2, CO, PPh3 or CS2 und er the chosen conditions. The corresponding anionic species Cp(CO)(n)M- wer e obtained when 1 was reacted with alkali metal benzophenyl ketyl. (C) 2000 Elsevier Science B.V. All rights reserved.