Cobalt complexes tetrazole

Nitrogen-bonded chromium(III) products are detected in the reductions of a number of pentaamine cobalt(III) tetrazole complexes by chromium(II). The rate laws show inverse [H dependences and rate constants consistent with an inner-sphere mechanism in all cases. Product isolation confirms remote attack by [Cr(H20)6 on the 4-cyanobenzoic acid derivative [(NH3)5CoNCC6H4C02H] and its deprotonated form (pX 2.51). The [V(H20)6] reaction is also consistent with a remote attack mechanism, while the 3-cyanobenzoic acid complex reacts by an outer-sphere pathway suggesting the possibility of a remote bridged outer-sphere... 

Despite the weak basicity of isoxazoles, complexes of the parent methyl and phenyl derivatives with numerous metal ions such as copper, zinc, cobalt, etc. have been described (79AHC(25) 147). Many transition metal cations form complexes with Imidazoles the coordination number is four to six (70AHC(12)103). The chemistry of pyrazole complexes has been especially well studied and coordination compounds are known with thlazoles and 1,2,4-triazoles. Tetrazole anions also form good ligands for heavy metals (77AHC(21)323). 

Far infrared data have been reported and v(M-N) frequencies assigned for a variety of cobalt, nickel, copper, zinc, cadmium, and mercury tetrazolate complexes (153). An inverse relationship between the basicity of the tetrazolate anions and the values of v(M-N) has been interpreted as evidence of significant M - L n bonding (153). 

Electronic spectra have been recorded for the 1,5-pentamethylene-tetrazole adducts MX2(l,5-pmtta) (M = Mn, Fe, Co, Ni, and Cu X = Cl and Br) (32) and for the complex salts [M(l,5-pmtta)6][C104]2 (M = Fe, Co, Ni, and Cu) (51, 52). Data for the complex salts indicate that 1,5-pentamethylenetetrazole is a stronger ligand than ethylene-diamine in the nickel(II) system but only slightly stronger than water in cobalt(II) complexes (51). 

EPR data have been reported for 5-aryl tetrazolate salts of copper(II) values are in the range 2.12-2.15 and the gL and gy values are similar to those recorded for copper(II) complexes of other N donors. Related cobalt and nickel complexes gave complex or unresolved spectra (119). EPR data have been analyzed for the complex salts [Mn(l,5-pmtta)6][C104]2 and [Cu(l,5-pmtta) ][C104]2 (n — 4 and 6). For the copper complexes, copper and nitrogen hyperfine splittings were observed (118). 

Table 26 Preparations Cobalt(III) Complexes Containing Imidazole and Tetrazole...

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