Nuclearity manipulation in Schiff-base fac-tricarbonyl complexes of Mn(I) and Re(I)

Abstract

A range of bidentate Schiff-base ligands, 2-(cyclohexyliminomethyl)phenol, 2-(cyclopentyl)methyl-5-methylphenol and 5-methyl-2-(phenylethyliminimethyl)phenol, with a variation in steric and electronic properties, were synthesized and coordinated to the fac-{MI(CO)3}+ core (M = Mn, Re). It is illustrated that the nuclearity for the rhenium complexes may be manipulated, i.e., either mono- or dinuclear complexes may be synthesized using virtually the same ligands and synthetic procedures. However, only dinuclear structures were isolated for manganese, in spite of applying very similar synthetic procedures as for rhenium. Four single crystal structures of the fac-[Mn(Sal-CyHex)(CO)3]2 (1), fac-[Mn(5-Me-Sal-CyPent)(CO)3]2 (2), fac-[Re(Sal-CyHex)(CO)3]2 (3), and fac-[Re(5-Me-Sal-EtPh)(CO)3(MeOH)] (4) are reported. The basic geometry was evaluated in detail and strain in the M-O1-M′-O1′ planar inner core was identified, referenced to literature and discussed. The conceptual relevance of these dinuclear complexes is the option of introducing one or two identical or different biologically active moieties into the same complex.