Abstract/Summary

Solvothermal synthesis has been used to prepare a number of main-group sulfides, oxysulfides, sulfates and an iron-selenide material. New phases were characterised using single-crystal X-ray diffraction to determine their structures followed by elemental analysis, powder X-ray diffraction, infra-red spectroscopy, Uv/vis diffuse reflectance spectroscopy, energy dispersive X-ray analysis, and, where appropriate, solid-state NMR and SQUID magnetometry. The reactions conducted with main-group metals resulted in the formation of antimony sulfide, indium sulfide and indium-antimony sulfide frameworks. (H1.33tren)[In2.67Sb1.33S8]·tren is the first example of a structure containing mixed In(III)/Sb(V) T2 supertetrahedal units that link through sulfur vertices to generate an open, 3- D framework containing pores in which the organic amine molecules reside. Other sulfides produced include: the discrete bicyclic unit [Co(tren)]2[μ-Ge2S6], 1-D structures [Co(tren)]2[Sb2In2S8] and [Fe(tren)][Sb2S4], 2-D structures [Co(tren)(H3tren)][In4SbS10].3H2O and [Co(tren)(H3tren)][In3Sb2S9].H2O, and 3-D structure (Hdap)6[In10S18]. The first examples of germanium oxysulfide (oxothiogermanate) compounds have been produced. A series of six materials incorporating discrete T2 supertetrahedral clusters of general formula [Ge4O6-xS4+x] 4- (x = 0, 2, 4) has been prepared, synthesised using a variety of tetra- and poly-amines. In [Co(dap)3)]2[Ge4O2S8], the T2 units are bridged by a GeO4 4- unit to form a new discrete germanate unit, [Ge9S8O14] 8- , while in [Co(deta)2]4[Ge9O14S8], the new [Ge9S8O14] 8- unit is manipulated to form a new 1-D chain, [Ge5O9(OH)2S2] 4- . With increasing sulfur -to-metal ratios, the optical band gap and thermal stability decrease. Transition-metal sulfates were prepared solvothermally in the presence of an amine, water and concentrated sulfuric acid. The magnetic properties of the discrete complex, [Co(Hdeta)2(SO4)2], and the chain-based structure (H24,4’-bipy)[Co(H2O)2(4,4’- bipy)(SO4)2].H2O, were investigated using SQUID magnetometry. Both exhibit antiferromagnetic behaviour but the discrete complex also shows weak ferromagnetic contributions at low temperature. Further chain-based compounds were also prepared: [Mn(SO4)(tepa)], [Co(SO4)(dap)2], [Co(SO4)(deta)] and the 3-D framework, [Co(SO4)(dab)]. A new iron-selenide compound, [Fe(en)3][FeSe2] was also discovered, adding to a small list of chain-based iron-selenide compounds that have been prepared solvothermally.