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In the reactions of bis(α-amino acidato)copper(II) with formaldehyde and benzamide, competing processes occur and the preferred pathway depends on the nature and number of the α-carbon substituents of the chelated amino acid, and the pH of the reaction medium. Aldol-type condensation yields complexes with oxazolidine ring(s) while Mannich aminomethylation results in the formation of complexes with N-methylbenzamido pendant arm(s). The crystal structure determination of bis(3-methylbenzamido-5-methyloxazolidine-4-carboxylato)copper(II) dihydrate establishes its formation from a combination of both processes, in which aldol condensation occurs first. The chemistry of these reactions is rationalized with a proposed reaction scheme. The synthesized compounds are characterized by infrared spectroscopy and microanalysis.

The reaction between diphenyltin(IV) dichloride and thiosemicarbazide using acetone–ethanol as solvent resulted in the formation of bis(acetone thiosemicarbazone-S)dichlorodiphenyltin(IV), SnPh 2 Cl 2 (atsc) 2 . The crystal structure determination of the compound revealed it to be a monomeric six-co-ordinated organotin(IV) complex. Each of the two atsc functions as a monodentate ligand, co-ordinating to the tin atom through the sulfur atom and conferring a distorted-octahedral geometry upon the tin. The Sn–S bond length is 2.712(1) A. The antifungal activity of the complex, atsc and SnPh 2 Cl 2 against four plant pathogens has been evaluated. The complex displays marked fungitoxicity against these fungi and is more fungitoxic than free atsc and SnPh 2 Cl 2 . It has also shown significant cytotoxicity against human colon adenocarcinoma, breast adenocarcinoma, hepatocellular carcinoma and acute lymphoblastic leukaemia.

The reaction of bis(glycinato)copper(II) with formaldehyde and benzaldehyde phenylhydrazone results in the formation of aquabis[2,3,4,5-tetrahydro-2,6-diphenyl-1,2,4-triazin-4-yl)acetato]copper(II) dihydrate, [Cu(L)2(H2O)]·2H2O, which has been structurally characterized by X-ray diffraction studies. The compound crystallizes in the monoclinic space group Cc, with unit-cell dimensions a= 35.222(9), b= 6.1 26(4), c= 15.986(7)A, β= 108.65(4)°, and Z= 4. The structure has been refined to R= 0.073 based on 1 128 independent observed reflections. The geometry about copper is grossly distorted octahedral with the two bidentate ligands occupying cis positions. A water molecule and a ‘free’ carboxyl oxygen atom from an adjacent (x,y+ 1,z) cell complete the six-coordination for copper. The latter two oxygen donor atoms, which are also cis, are at greater distances from the Cu atom than the oxygen and nitrogen donors from L.

The novel zinc(II) complex formed by the reaction of formaldehyde with bis(glycinato)zinc(II) monohydrate in the absence of base has been shown by X-ray diffraction to be bis[N-(1,3-dioxa-5-azacyclohexyl)acetato]zinc(II) dihydrate.