Actinide structural studies. Part 17. The crystal and molecular structures of four uranyl(VI) complexes with N,N-dialkyldithiocarbamate ligands

Abstract

The synthesis and crystal structures are reported of four dithiocarbamates of general formula [NR₄][UO₂(dtc)₃]: [1; R = Et, dtc =N-tetramethylenedithiocarbamate (C₄H₈NCS₂)], R= 0.040 for 3 970 observed [I/σ(I) 3.0] reflections; [2; R = Et, dtc =N- pentamethylenedithiocarbamate (C₅H₁₀NCS₂)], R= 0;057 for 5 729 reflections; [3; R = Et, dtc =N,N-dimethyldithiocarbamate (Me₂NCS₂)], R= 0.054 for 3 722 reflections; [4; R = Me, dtc =N,N-diethyldithiocarbamate (Et₂NCS₂)], R= 0.049 for 3 192 reflections. All four complexes exhibit hexagonal bipyramidal geometry about the central uranium atom, involving three bidentate dithiocarbamate molecules co-ordinated in the equatorial plane of the uranyl ion. The U–O(UO₂²⁺) bond lengths are in the range 1.734(11)–1.862(12)Å. The U–S distances are almost equal in all the complexes [2.946(2)Å mean]. The equatorial planes show significant puckering to accommodate the six sulphur atoms [maximum deviation 0.32(5)Å]. Intra-ligand S ⋯ S distances (ligand bite) are in the range 2.856(4)–2.891(4)Å and inter-ligand distances are in the range 2.911(4)–3.109(4)Å.