Two-dimensional metallic chain compounds Y5M2Te2 (M = Fe, Co, Ni) that are related to Gd3MnI3. The hydride derivative Y5Ni2Te2D0.4.

Y(5)M(2)Te(2) (M = Fe, Co, Ni) have been prepared by high-temperature solid-state techniques and shown to be isostructural and orthorhombic Cmcm (No. 63), Z = 4. The structure was established by single crystal X-ray methods at 23 degrees C for M = Fe, with a = 3.9594(3) A, b = 15.057(1) A, and c = 15.216(1) A. The new structure contains zigzag chains of the late transition metal sheathed by a column of yttrium atoms that are in turn condensed through trans vertices on the latter to yield 2D bimetallic layers separated by single layers of tellurium atoms. Reaction of hydrogen with Y(5)Ni(2)Te(2) causes a rumpling of the Y-Ni layers as determined by both single X-ray crystal means at 23 degrees C and neutron powder diffraction at -259 degrees C for Y(5)Ni(2)Te(2)D(0.41(1)), Pnma (No. 62), Z = 4. Lattice constants from the former study are a = 14.3678(7) A, b = 4.0173(2) A, and c = 15.8787(7) A. The hydrogen is accommodated in tetrahedral yttrium cavities generated by bending the formerly flat sheets at the trans Y vertices. A higher hydride version also exists. Band structure calculations confirm the 2D metal-bonded character of the compounds and also help illustrate the bonding/matrix changes that accompany the bonding of hydrogen. The ternary structures for both Y(5)M(2)Te(2) and Sc(5)Ni(2)Te(2) can be derived from that of Gd(3)MnI(3), the group illustrating three different kinds of metal chain condensation.