SYNTHESIS AND CRYSTAL STRUCTURE OF A NEW TERNARY TANTALUM CHALCOGENIDE Ni2Ta2Te4

The compound Ni2Ta2Te4 is obtained by heating the elements at 1000℃ in evacuated silica tube. Mr=989.70, orthorhombic system,space group Pma2,a = 7.914(1),b= 6.2372(5),c=7.2362(6)A,V = 357.2(1)A3, Z = 2, DC = 9.201 g/ca3,λ(MoKα)=0.7093A,μ= 537.90Cm-1.F(000)=820. Final R=0.083 and Rw=0.103 for 889 reflections.This compound is iso-structural to Ni2Nb2Te4,with two-dimensional(2D) network structure. In each cluster unit,two Ni and two Ta atons form a rhombic plane with four Ni-Ta bonds (average 2.655 A) and one Ni-Ni bond (2.512 A) without Ta-Ta interac-action. The distorted tetrahedral coordination of each metal atons is completed by four Te atoms.The average distances are 2.792A for bonds Ta-Te and 2.556 A for bonds Ni-Te.