X-Ray crystal structures of bis-(2-mercapto-4′-methylazobenzene)nickel( II ) and bis-(2-hydroxy-4′-methylazobenzene)nickel( II ): five-membered metallocycle in the former complex

X-Ray structural data for the bis-azobenzene-nickel(II) complexes (I) and (II) show that the donor atom X influences the size of the metallocycle and the bonding arrangement around nickel; in (I)(X = S) the metallocycle is five-membered, whereas in (II)(X = O) it is six-membered.