The effect of remote substitution on formation of preferential geometrical isomer of cobalt(III)–tetrazolato complexes formed via [2 + 3] cycloaddition

Two bistetrazolato complexes cis-[Co(5-phenyl-tetrazolato)2(en)2](NO3) (1) and trans-[Co{5-(4-chlorophenyl)-tetrazolato}2(en)2]NO3 (2) have been synthesized starting from the diazide cobalt complex [Co(N3)2(en)2]NO3 and two different organonitriles using microwave irradiation technique. It has been found that the remote substitution at 4-position of phenyl ring exhibits an influence on the geometrical preference of cycloadded metal complex. Theoretical investigation revealed that compound 1 is a kinetic product whereas stability of compound 2 has been driven by extra thermodynamical stability out of additional halogen–halogen interaction.