Coordination Chemistry of 3‐Mercapto‐2‐(mercaptomethyl)propanoic Acid (Dihydroasparagusic Acid) with Iron and Nickel

Abstract

Abstract The first transition‐metal complexes bearing the natural product dihydroasparagusic acid, (HSCH 2 ) 2 CHCO 2 H, as a ligand are reported. Various coordination modes and nuclearities are demonstrated for the chelating ligand by a series of iron and nickel complexes. Fe 2 [(SCH 2 ) 2 CHCO 2 H](CO) 6 retains carbonyl substitution reactivity typical of Fe 2 (SR) 2 (CO) 6 complexes, yet carboxy coordination to Fe I was unobserved. Coupling of the carboxylic acid with amines yields the corresponding amides Fe 2 [(SCH 2 ) 2 CHC(O)NHR](CO) 6 (R = Et, gly– O – t Bu). Fe 2 [(SCH 2 ) 2 CHCO 2 H](CO) 4 (PMe 3 ) 2 catalyzes H 2 production, but no better than unfunctionalized alkyl dithiolate analogs. Reactions of the ligand with NiCl 2 (dppe) afforded mono‐, di‐, and trinuclear complexes. Noteworthy is Ni 3 [(SCH 2 ) 2 CHCO 2 ] 2 (dppe) 2 , which features an octahedrally coordinated Ni II center linked to a pair of square‐planar Ni II centers. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)