Synthesis, structure and light scattering properties of tetraalkylammonium metal isothiocyanate salts†
A series of ammonium and tetraalkylammonium metal isothiocyanate salts of the type Qy[M(NCS)x] (M = Cr(III), x = 6, y = 3, Q = NH4+, Me4N+, Et4N+, n-Bu4N+; M = Mn(II), x = 6, y = 4, Q = Me4N+; M = Mn(II), x = 5, y = 3, Q = Et4N+; M = Fe(III), x = 6, y = 3, Q = Me4N+, Et4N+, n-Bu4N+; M = Co(II), x = 4, y = 2, Q = n-Bu4N+; M = Eu(III), Gd(III), Dy(III), x = 6, y = 3, Q = Bu4N+) has been synthesized and structurally characterized. The octahedral Cr(III) salts are isostructural to previously and newly reported Fe(III) salts. The Ln(III)-containing anions are also octahedral. For Mn(II), although the Me4N+ salt is octahedral, the Et4N+ salt [Mn(NCS)5]3− possesses a distorted trigonal bipyramidal geometry. For (Et4N)3[Fe(NCS)6] and (n-Bu4N)3[Fe(NCS)6], a solid-state size-dependent change in colour from red to green was observed and was attributed to a light scattering phenomenon in the crystalline samples.