Iron and Manganese Complexes of 2-Carbonyl Pyrrolyls: Scorpionate Sandwich Anions and Extended Structures

Abstract

Attempts to synthesize complexes of Fe and Mn(II) with 2-amidopyrrolyl ligands (N-O) were unsuccessful, and only small amounts of the trivalent tris complexes M(N-O) 3 were detected, although unusually in the case of Fe(III) a fac structure is observed. In contrast the 2-benzoylpyrrolyl systems give M(II) complexes, and in all instances thus far where Na + is present, a scorpionate fac-[M II (N-O) 3 ] - unit self-assembles into sandwich anions [M II (N-O) 3 Na(O-N) 3 M II ] - in which the central metal is efficiently encapsulated by interdigitation of the aryl units. Extended structures are readily made through the use of a 2-(4-pyridinoyl)pyrrolylamide ligand. When Li + is used, the scorpionate ligand is not assembled, and instead [M(N-O) 2 ] units give rhombic 2D grids. The Fe system displays spin-crossover at 120 K. (Figure Presented).