Polymers in Form of Linked Rings - A Novel Type of Structures for Chalcogen Polycations: The Crystal Structures of (Se_4.85Te_3.15)[WOCl₄]₂ AND (Se₄Te₃)[WOCl₄]₂

Abstract

Among the well developed structural chemistry of the chalcogen polycations polymeric, chainlike entities represent a new feature, known only since 1990. Examples are (Te₁₅X₄)_n[MOX₄]_2n (M=Mo, W; X=Cl, Br), Te₇[MOX₄]X (M=W, Nb; X=Cl, Br) or Te₇[AsF₆]₂. The reaction of Te₆[WOCl₄]2 with selenium or Se/Te mixtures with WOCl₄ yielded (Se_4.85Te_3.15)[WOCl₄]₂ (orthorhombic, P2₁2₁2₁, a=782.1(3), b=1549.0(6), c=1824(l) pm, Z=4) and (Se₄Te₃)[WOCl₄]₂ (monoclinic, Cc, a=l198.7(5), b=1072.0(6), c=1563.9(7) pm, β=100.80(3)°, Z=4). Both structures contain Se/Te mixed, polymeric cations and square pyramidal [WOCl₄]⁻ anions linked via W=0.....W.bridges to linear strands. In (Se_4.85Te_3.15)²⁺ all sites are simultaneously occupied by Se and Te but with different amounts. The cations form five-membered rings linked in 1,3 positions by three-atomic bridges to chains. In (Se₄Te₃)²⁺ the atomic positions are occupied by Se and Te in an ordered way. The cations are built from four-membered rings connected in 1,3 positions by three-atomic bridges to chains. Te atoms are located in the two three-coordinate positions in the rings and the central position in the connecting bridges.

Keywords::

• chalcogen polycations
• main group element clusters
• Oxotetrachlorotungstate(V)
• synthesis
• crystal structure