Synthesis and X-ray characterization of new 1-[mu-dithio-bis-(tricarbonyliron)]-2-(p-R-benzoyl)ethane complexes

Diiron nonacarbonyl reacts with the para-substituted derivatives 1a-d of 3,3-dithio-1-(p-substituted phenyl)-2propen-1-one affording surprisingly the new dinuclear Fe(0) complexes 2a-d with a sigma-S coordination instead of the attended eta(2) or eta(4) pi-coordination upon the alpha,beta-unsaturated system of the ligands. The complexes 2a-c were characterized by mass spectrometry, IR and H-1- and C-13-NMR spectroscopies and their structures were fully confirmed by single-crystal X-ray analysis. Such structural studies revealed as the main feature an ideal C-2v (mm(2)) symmetry with the carbonyl groups in an eclipsed configuration of the Se2Fe2(CO)(6) moiety. (C) 1999 Elsevier Science S.A. All rights reserved