X-RAY CRYSTAL-STRUCTURES OF [BI(C2H2N2S3)(SCN)(3)](1) AND CS2K[BI(SCN)(6)](2) - AN UNUSUAL PENTAGONAL-PYRAMIDAL COORDINATION OF BI-III IN (1)

The new complex of Bi(SCN)(3) with the isoperthiocyanic acid: [Bi(C2H2 N2S3)(SCN)(3)] (1) has been obtained during the attempted recrystalliz ation of Dy[Bi(SCN)(6)]. 6H(2)O from HClO4. Compound (1) and CsK[Bi(SC N)(6)](2) have been investigated by X-ray crystallography. The unusual shape of deformed pentagonal pyramidal coordination of Bi-III in (1) and typical octahedral coordination in (2) have been observed. The ana lysis of Bi--S and Bi--N bond lengths in home and hetero-ligand thiocy anato Bi-III complexes of different coordination numbers is made on th e basis of the bond's valences, computed from our literature and exper imental data. The role of the Bi-III lone electron pair on the shape o f Bi-III coordination polyhedra is considered. Copyright (C) 1996 Else vier Science Ltd