Carbonyl complexes of manganese, rhenium and molybdenum with 2-pyridylimino acid ligands

[MBr(CO)3{κ2(N,O)-pyca}] [M = Mn(1a), Re(1b), pyca = pyridine-2-carboxaldehyde] and [MoCl(η3-C3H4Me-2)(CO)2{κ2(N,O)-pyca}] (1c) react with aminoacid β-alanine to give the corresponding iminopyridine complexes 2a–2c. The same method affords the iminopyridine derivatives from γ-aminobutyric acid (GABA) (3a–3c) and 3-aminobenzoic acid (4a–4c). For complexes 2a–2c, 3a, 3c and 4a, the solid state structures have been determined by X-ray crystallography, revealing interesting differences in their hydrogen-bonding patterns in solid state.