Structural and NMR Studies of the Hexameric Copper(I) Complex with N ‐n‐butyl‐ N ′‐ethoxycarbonyl‐thioureate

The copper sulfide mineral flotation collector, N ‐n‐butyl‐ N ′‐ethoxycarbonyl‐thiourea (H 2 bectu), and the 1:1 hexameric copper(I) thioureate complex, [Cu(Hbectu)] 6 , have been characterized by single crystal X‐ray diffraction. H 2 bectu crystallizes in the triclinic space group $\rm P{\bar 1}$ with a = 5.2754(4), b = 9.0042(7), c = 12.6030(9) Å, α = 80.528(6), β = 90.173(6), γ = 76.472(7)°. An intramolecular N‐H···O hydrogen bond between the thioamide proton and carbonyl oxygen forms a planar six‐membered ring in the central core of the molecule with C=O, C=S and C‐N bond lengths in accord with those reported for other N ‐alkyl/aryl‐ N ′‐acyl‐thiourea compounds. [Cu(Hbectu)] 6 crystallizes in the monoclinic space group C2/c with a = 23.269(5), b = 13.243(4), c = 23.037(7) Å, β = 91.81(2)° as discrete hexameric clusters disposed about a crystallographic centre of symmetry with a Cu 6 S 6 core consisting of two Cu 3 S 3 chair‐shaped rings linked by coordination of the deprotonated amide nitrogen atom to a copper atom in the adjacent ring. The six ligands assemble as a paddlewheel structure with the ethoxy and n‐butyl substituents packing in an alternating head to tail arrangement. Temperature dependent solution 1 H NMR spectroscopic studies show that the hexameric structure of the complex is maintained in solution.