Cd(NCS) 2 crystallizes in P2 1 /c and has only a single Cd 2+ site, octahedrally coordinated by thiocyanate to produce a trans-CdS 4 N 2 coordination polyhedron. Every thiocyanate has the S-terminus doubly coordinated, and the N-terminus singly coordinated. Thus far the description of Cd(NCS) 2 is identical to that of Ni(NCS) 2 , however in Cd(NCS) 2 there are two distinct NCS - ions, and the overall connectivity of the framework is 3D. The structure is thus analogous to the MnO 2 ramsdellite or Al(OH)O diaspore structure-types. Sn(NCS) 2 adopts a unique structure and crystallizes in P1 with a prominent stereochemically active lone pair. There is a single Sn ion, which is three-coordinate, SnN 2 S, with one N-bound terminal NCS -, and two bridging NCS -anions. This produces a 1D coordination polymer connected into 2D sheets via weak supramolecular Sn• • • S interactions, which might be considered 'tetrel-bonds'. The low symmetry of the structure means that the bond lengths vary widely and alternative descriptions are admitted. Sn(NCS) 2 appears to be a promising electron-transport layer for photovoltaic devices 103,104 Tin(II) thiocyanate crystallizes from aqueous solution of Sn(SO 4 ) and Na(NCS), whereas Zn(NCS) 2 and Cd(NCS) 2 can be prepared by salt metathesis between the metal sulfate and Ba(NCS) 2 in water.