Dimeric and trimeric molybdenum( II) complexes containing 2-substituted η3-bonded butadienyl bridging ligands

Article abstract of DOI:10.1016/s0022-328x(97)00456-7

Reaction of [MoCl(CO)₂(η³-CH₂(COCl)C=CH₂)phen] (phen = 1,10-phenanthroline) (1) with 1,2-ethanediol or N,N′-diethylethylenediamine in 2:1 mole ratio gave dimeric complexes [MoCl(CO)₂(η³-CH₂(COACH₂)C=CH₂)phen]₂ containing two molybdenum centres bridged by a pair of η³-bonded butadienyl units linked by 2-substituted ester (A = O) or amide (A = NEt) groups. Analogous reactions involving hydroquinone or 1,4-phenylenediamine led to monomeric complexes of the type [MoCl(CO)₂(η³-CH₂(COA)C=CH₂)phen] (A = OC₆H₄OH, NHC₆H₄NH₂), however, dimeric complexes were isolated from reactions involving 4,4′-ethylenedianiline or p-xylylenediamine. Attempts to prepare a novel complex bridged by three linked amide substituted butadienyl groups using diethylenetriamine were unsuccessful, however, reaction of 1 and triethanolamine or tris(2-aminoethyl)amine in 3:1 mole ratio gave trimeric complexes [MoCl(CO)₂(η³-CH₂(COACH₂CH₂)C=CH₂)phen]₃N (A = O, NH) in good yield.