A powder neutron diffraction study on the low-temperature modification of Cs2PbCu(NO2)6 yielded a monoclinic unit cell [space group B2/b with a′=773.4(3) pm, b′=1553.1(6) pm, c′=2137.6(8) pm, γ′=90.10(1), and Z=8], which deviates only slightly from tetragonal. Though a thorough structure determination was not possible, the essential features of the structure are clearly revealed. The CuN6 octahedra are tetragonally elongated with a small orthorhombic component superimposed [bond lengths c′, 211.5 pm (2x) and 230 pm (2x);‖c, 207 pm]. The cooperative Jahn-Teller order pattern corresponds to the antiferrodistortive model.
Copper-lead nitrocomplexes exhibit multistage transitions between phases, which are characterized by static, planar dynamic and three-dimensionally dynamic Jahn-Teller effects, respectively. In this study the structure of the cubic high-temperature α-modification of Cs2PbCu(NO2)6 and the nature of the α ⇌ β-phase transition is investigated by neutron diffraction.
The structure of the (SN)x polymer metal has been redetermined at room temperature by using neutron diffraction on single crystals. It is characterized by endless strands of N and S atoms with equal intrachain distances of d (SN)intra = 1.585 Å. The intrachain bond angles at S and N atoms are 107.0 and 120.3o, respectively. The shortest interchain distances (d(SN)inter = 3.26 Å, d(NN)inter = 3.34 Å, and d(SS)inter = 3.47 Å) are in the range of the sum of the van der Waals radii. Besides the N and S sites of the ordinary strands additional defect sites were found.
