Synthetic and structural studies on bismuth(III) thiocyanate and selenocyanate complexes

Abstract

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)₃A. Compound A and 2 equivalents of K[Mo(CO)₃(η-C₅H₅)] afforded the green complex [Bi(SCN){Mo(CO)₃(η-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(η-C₅H₅) fragments with additional intermolecular Bi ⋯ NCS interactions resulting in a one-dimensional polymer. The reaction between A and [K(18-crown-6)]SCN (18-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(η-C₅H₅)}₃] afforded [Bi(SeCN){Mo(CO)₃(η-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].