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Biochemical research involving a novel class of organocobalt models [LCo(N-CH2-CHEL)]X shows steric bulk binding interaction differences between the ligands of the analogs 1,5,6-trimethylbenzimidazole and N-methylimidazole. Evidence indicates that steric interactions involving the equatorial ligand do not determine the angle of Co-N(5)-C bonds. The highly distorted N4 equatorial ligation seems to be caused by the Me3Bzm Lone pair of electrons.

The ligand exchange interactions between N2S2 dithiourea (DTU) ligands, RNHC(=S)NH(CH2)3NHC(=S)NHR, and Re(V) precursors form neutral Re(super V)=O(N2S2) complexes. Structural studies of (1-phenyl-3-(3-(3-phenylthioureido)propyl)thioureato)oxorhenium(V) indicate a pseudo-square-pyramidal geometry with an apical oxo donor and an N2S2 basal set. One uncoordinated N of the DTU ligands is deprotonated and forms a dianionic four-membered N,S chelate ring. The two coordinated N's are deprotonated.

UV-visible, 1H NMR, and Raman resonance spectra indicate that the enantiomers of oxo(D-penicillaminato)(L-penicillaminato)rhenate(V) (1) interconvert in a fast base-catalyzed reaction to trans form (I). Substantial carboxyl group deligation occurs at pH 11, when I is converted to form II. The rate of interconversion is proportional to hydroxyl concentration. Axial hydroxo coordination is favored in 1 compared to ReO(D-penH3)(D-penH2). The NMR spectrum and Re=O band of 1 indicate that II is a trans-dioxo species.