SYNTHETIC AND STRUCTURAL STUDIES ON BISMUTH(III) THIOCYANATE AND SELENOCYANATE COMPLEXES

The reaction between either BiCl3 or Bi(NO3)3.5H2O and 3 equivalents of KSCN afforded a yellow material which has not been fully characterised but which reacts as a source of Bi(SCN)3 A. Compound A and 2 equivalents of K[Mo(CO)3(eta-C5H5)] afforded the green complex [Bi(SCN){Mo(CO)3(eta-C5H5)}2] which has been characterised by X-ray crystallography and consists of trigonal-pyramidal bismuth centres co-ordinated to one SCN group through sulfur, and two Mo(CO)3(eta-C5H5) fragments with additional intermolecular Bi...NCS interactions resulting in a one-dimensional polymer. The reaction between A and [K(18-crown-6)]SCN (1 8-crown-6 = 1,4,7,10,13,16-hexaoxacyclooctadecane) afforded an orange and a yellow crystalline material both of which have been characterised by X-ray crystallography and shown to be isomers. In the orange compound a potassium cation is located between two potassium cations co-ordinated by 18-crown-6 ligands and an octahedral [Bi(SCN)6]3- anion is present. These ions are organised into two-dimensional sheets in which each [Bi(SCN)6]3- anion is surrounded by four K[K(18-crown-6)]2 units and vice versa. In the yellow compound the structure has the same basic cationic and anionic units but the thiocyanatobismuth anion has four S-bonded and two trans N-bonded thiocyanate ligands with the anions arranged in parallel columns separated (within columns) by potassium cations. The remaining two potassium cations are co-ordinated by 18-crown-6 ether ligands and are positioned between the columns. The reaction between BiCl3 and 3 equivalents of KSeCN afforded dark red crystals of a complex formulated as Bi(SeCN)3. The reaction between Bi(SeCN)3 and 2 equivalents of [Bi{Mo(CO)3(eta-C5H5)}3] afforded [Bi(SeCN){Mo(CO)3(eta-C5H5)}2]. The reaction of [N(PPh3)2] [BiCl4] and 4 equivalents of KSeCN afforded a dark red crystalline compound K[N(PPh3)2]2[Bi(SeCN)6] the structure of which was also established by X-ray crystallography and comprises isolated [N (PPh3)2]+ cations and columns of [Bi(SeCN)6]3- anions separated by potassium cations in a similar manner to that found in yellow K[K(18-crown-6)]2[Bi(SCN)4(NCS)2].