Containing metal-oxygen bonds sulfur ligands

Most of the first row transition elements, and Cd, exhibit intermediate bonding preferences, sometimes occurring in chelation matrices containing both oxygen and nitrogen or sulfur ligands. Because Cd has been the subject of considerable toxicological study in marine systems, Cd++ will be used as an example of a borderline metal ion. 

A study of the interaction of ligand (88) with alkali metal complexes has been reported.423 The NaNCS complex contains the ligand bound to the Na+ by five oxygen donors but the sulfur does hot interact at all the six coordination of the cation is completed by the NCS- anion.424 The KNCS complex has the metal at the centre of a hexagon of donors, all of interact with the metal, 2S and in the RbNCS complex the Rb+ sits out of the plane towards an N-bonded NCS- anion and is also coordinated by a sulfur from an adjacent ring to give a dimeric structure.426... 

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