The geometry optimizations of structures of four deprotonated forms (L 4− , LH 3− , LH22− and LH3−) of N,N′-propylene bis(benzohydroxamamide), (C 3 (BHam) 2 =LH 4 ) and their oxotechnetium(v) and oxorhenium(v) complexes have been carried out using ab initio HF and DFT methods with LANL2DZ and 6-31G(d) basis sets. The protonation of various species of C 3 (BHam) 2 , L 4− , LH 3− , LH22− and LH3− was studied. The relative stabilities of oxotechnetium(v) and oxorhenium(v) complexes with various species of C 3 (BHam) 2 are serially reported. The most stable epimers of the oxotechnetium(v) and oxorhenium(v) complexes are the isomers of anti-[LTcO] − and anti-[LReO] − , respectively.