M(SCN)2 (M = Eu, Sr, Ba):: Crystal structure, thermal behaviour, vibrational spectroscopy

Single crystals of M(SCN)(2) (M = Eu, Sr, Ba) have been obtained via metathesis of NaSCN and MCl2 (M = Eu, Sr, Ba) at 340 degreesC. The isotypic crystal structures of the thiocyanates M(SCN)(2) (C2/c, Z=4, Eu: a=979.3(2), b = 660.8(1), c = 815.7(2) pm, beta= 91.58(3)degrees, R-all = 0.0245, Sr: a=985.5(2), b=662.9(2), c=819.6(2) pm, beta =91.29(3)degrees, R-all= 0.0435, Ba: a = 1018.8(2), b = 687.2(1), c = 852.2(1) pm, beta = 92.43(2)degrees, R-all= 0.0392) contain alternating layers of M2+ and SCN-. According to M(SCN)(4/4)(NCS)(4/4) M2+ is eight-coordinated by four sulfur and four nitrogen atoms forming a square antiprism. Thermal investigations show that the compounds melt without decomposition. Vibrational spectroscopic investigations are presented and discussed.