SYNTHESES AND STRUCTURES OF CLUSTER COMPOUNDS CONTAINING WSe₄Cun (n = 3,4) CORES WITH DIALKYLDITHIOCARBAMATE LIGANDS

Abstract

The reactions of [Et₄N]₂[WSe₄] with three equivalents of CuCl in the presence of NaS₂CNR₂ (R = Me, Et) yielded two W-Cu-Se compounds, [Et₄N]₂[WCu₃Se₄(Et₂NCS₂)₃] (1) and [Et₄N]₂-[WCu₄Se₄(Me₂NCS₂)₄] (2). [Et₄N]₂[MoCu₃Se₄(Et₂NCS₂)₃] (1) crystallizes in the orthorhombic space group P2₁2₁2₁ with cell dimensions a = 12.976(3), b = 13.336(3) and c = 29.738(6)Å, V = 5153.8(13)ų, Z = 4. Full anisotropic refinement of the structure led to convergence at R = 0.061 (R_w = 0.070) for 453 variables and 5913 reflections with F>4.0σ(F). The [WCu₃-Se₄(Et₂NCS₂)₃]^2- anion in 1 comprises three Et₂NCS₂Cu fragments linked by a slightly distorted tetrahedral WSe₄ moiety. Compound 2 crystallizes in the orthorhombic space group Pbca with cell constants a = 14.698(3), b = 18.473(4), c = 37.182(5)Å, V = 10095.6(33) ų and Z = 8. Anisotropic refinement with 5839 reflections (F > 6.0σ(F)) and 460 parameters for all non-hydrogen atoms yielded the values R = 0.061 and R_w = 0.073. The [WCu₄Se₄(Me₂NCS₂)₄]^2- anion structure of 2 possesses pseudo D_2d symmetry for the WSe₄Cu₄ core and a nearly planar WCu₄ array and consists of four Me₂NCS₂Cu fragments coordinated across four edges of the tetrahedral [WSe₄]^2- group. IR and electronic spectroscopic data for the two compounds are reported.

Key Words:

• W-Cu-Se cluster
• crystal structure