Neutron scattering study of the layered Ising magnet CsDy(MoO₄)₂

The quasi-two-dimensional antiferromagnet CsDy(MoO₄)₂ is studied by neutron diffraction and quasielastic neutron scattering. The crystal structure of two low-temperature phases (below 120 K and below 40 K) is determined. An approximate structure of the magnetically ordered phase (TN = 1.36 K) is proposed. In the ordered state the order-parameter critical exponent β = 0.17(0.01), the in-plane correlation length exponent ν = 0.94(0.07), and the staggered susceptibility critical index γ= 1.01(0.04) were determined. Comparing these results to the exact solution for a 2D Ising magnet we conclude that, although 2D behavior is apparent in CsDy(MoO₄)₂, there are deviations from the simple 2D Ising model

Neutron diffraction analysis of the first stable hydride derivative of a divalent group-14 metal

A single-crystal neutron diffraction study at 20 K has revealed accurate hydride ligand positions in the first stable hydride derivative of a divalent group-14 metal, [2,6-Trip2C6H3Sn(\u3bc-H)]2\ub74C6H6, Trip = 2,4,6-tri-isopropylphenyl [B.E. Eichler, P.P. Power, J. Am. Chem. Soc. 122 (2000) 8785]. In the solid state this dimeric complex assumes a trans C2h geometry with two bridging hydrides (Sn\u2013H 1.943(7) \uc5, angle C\u2013Sn\u2013H 92.4(2)\ub0, angleSn\u2013H\u2013Sn\u2032 106.9(3)\ub0, angle H\u2013Sn\u2013H\u2032 73.1(3)\ub0). The bulky Trip ligand serves to stabilize the Sn\u2013H bonds. The tin atoms carry lone pairs, and, as determined previously by X-ray diffraction and reported by Eichler and Power, the tin coordination accordingly is pyramidal as evidenced by the sum of the three bond angles around tin of 257\ub0. To our knowledge this is the first neutron diffraction study of a tin hydride complex to be reported. The neutron diffraction measurements were carried out using the time-of-flight Laue SCD instrument at the Argonne Intense Pulsed Neutron Source