Transition metal complexes of amidinourea and related ligands part III. Infrared spectra and thermal decomposition studies on metal complexes of O-alkyl-1-amidinoureas

Summary The i.r. spectral data on O-methyl-l-amidinourea hydrochloride,O-ethyl-1-amid inourea hydrochloride and the metal complexes M = copper(H), nickel(II), palladium(II), zinc(II) and oxovanadium(IV)] ofO-methyl-l-amid inourea andO-ethyl-l-amidinourea are reported. The spectral results suggest that secondary amine nitrogens are the donor atoms inO-alkyl-1-amid inourea. The free ligands and the complexes exhibit a characteristic band at ca. 1100 cm^–1 due to the C-OR group. The i.r. and electronic spectral data on the hydrated and anhydrous uncharged metal complexes indicate that the hydrated uncharged metal complexes ofO-alkyl-l-amidinourea may be represented as M(AAU)_n]] · xH₂0 and not as M(AAUII)_n](OH)_n · xH₂O where AAU = H₂NC(=NH)NC(=NH)OR and AAUH = H₂NC(=NH)NHC(=NH)OR, R = Me, Et]. The use of the term anhydrobase is confusing and suitable names for various metal complexes ofO-alkyl-l-amid inourea are suggested. The main decomposition stage in metal complexes ofO-ethyl-l-amidinourea occurs at lower temperatures than for the corresponding biguanide complexes indicating that the former are less stable than the latter.