Y10I13C2: a novel compound with chains of both carbon-centered and empty clusters

The phase Y{sub 10}I{sub 13}C{sub 2} is synthesized by the reaction at {approximately} 800{degree}C of powdered Y and YI{sub 3} with impure Y{sub 2}O{sub 3}, the vital carbon component resulting from incomplete decomposition of the yttrium oxalate precursor. The phase has not been obtained from more conventional carbon sources. The identity of carbon as the interstitial is supported by these syntheses, microprobe analyses of Y{sub 10}I{sub 13}C{sub 2} vs Y{sub 6}I{sub 7}C{sub 2}, and both the occupancy and the dimensions of the yttrium cavity in which carbon occurs. The phase occurs in space group C2/m, Z = 2; a = 21.317 (6) {angstrom}; c = 19.899 (5) {angstrom}; {beta} = 97.40 (2){degree}; R/R{sub w} = 3.3%/3.9% for 838 independent reflections with 2{theta} {le} 50{degree} (Mo K{alpha}). The compound consists of centered Y{sub 6}I{sub 12}C- and empty Y{sub 6}I{sub 8}-type clusters condensed by edge sharing into commensurate double and single chains, respectively. The chains are further cross-linked by additional iodine atoms. The two chain types are very similar to those known individually in the phases Y{sub 6}I{sub 7}C{sub 2} and Y{sub 4}Cl{sub 6} and are presumably metallic and semiconducting, respectively. The Y{sub 4}I{sub 6} chain is the first iodide example ofmore » condensed Y{sub 6}X{sub 8}-type clusters. This feature appears to be stabilized in this structure by a sterically less demanding means of bridging these chains between sheets of a Y{sub 6}I{sub 7}C{sub 2}-like arrangement. 30 refs., 3 figs., 3 tabs.« less