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

Abstract

Reaction of [MoCl(CO) 2( η 3-CH 2(COCl)C=CH 2)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( η 3-CH 2(COACH 2)C=CH 2)phen] 2 containing two molybdenum centres bridged by a pair of η 3-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( η 3-CH 2(COA)C=CH 2)phen] (A = OC 6H 4OH, NHC 6H 4NH 2), 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( η 3-CH 2(COACH 2CH 2)C=CH 2)phen] 3N (A = O, NH) in good yield.