The effect of remote substitution on the formation of preferential isomers of cobalt(iii)-tetrazolate complexes by microwave assisted cycloaddition

Abstract

Cycloaddition of cis-[Co(N3)2(en)2]NO31 or trans-[Co(N3)2(en)2]ClO41a with organonitriles affords cis/trans cobalt bis-tetrazolate complexes, depending upon ligand substitution, solvent molecules and counteranions.

Improvement of the Biological Activity of a New Cobalt(III) Complex through Loading into a Nanocarrier, and the Characterization Thereof

“…The absorption spectrum for complex 1 in aqueous solution showed two absorption bands in the UV region, at around 202 (λ max ) and 283 nm, attributed to the π→ π* transition in the ligand. Above 400 nm, a weak broad peak is observed at around 561 nm that can be assigned to d‐d transitions of the low spin Co(III) center ( 1 A 1g → 1 T 1g transitions) …”

“…The Co(III) cation in the [Co(en) 2 (mtzt) 2 ] + is six‐coordinated in a distorted octahedral geometry by four N atoms from two ethylenediamine ligands in equatorial positions and two N atoms from two mtzt ‐ anions in axial positions. In this complex, the average of Co‐N en and Co‐N mtzt bond lengths, 1.955(3) and 1.955(2)Å, are similar to those found in trans ‐[Co(mtt) 2 (en) 2 ](mtt), 1.956(6) and 1.956(6)Å, respectively (mtt − is 5‐methyl‐1,3,4‐thiadiazole‐2‐thiolate), but is slightly larger than that found in trans ‐[Co(Cl‐tetrazolato) 2 (en) 2 ]NO 3 , 1.937(3) and 1.916(3)Å, respectively (Cl‐tetrazolato is 5‐(4‐chlorophenyl)‐tetrazolato) …”

Alternative Technologies That Facilitate Access to Discrete Metal Complexes

“…Microwave-assisted 1,3-dipolar cycloaddition reaction of cis -[Co­(N 3 ) 2 (en) 2 ]­NO 3 396 (en = 1,2-ethylenediamine) with different organonitriles (R-CN) produced the bistetrazolate [Co­(N 4 CR) 2 (en) 2 ]­(NO 3 ) 397 and 398 in 1–3 h at 130 °C . Interestingly, changing the nitrile (R = 3-NC 5 H 4 , 4-NC 5 H 4 , and 4-BrC 6 H 4 ) gave different ratios of isomers (Scheme ).…”