Mo3Q7 (Q = S, Se) Clusters Containing Dithiolate/Diselenolate Ligands: Synthesis, Structures, and Their Use as Precursors of Magnetic Single-Component Molecular Conductors

Abstract

The coordination chemistry of dithiolene and diselenolene ligands towards the all-selenium [Mo3Se7Br6]2– dianion has been investigated. Complexes (nBu4N)2[Zn(dmit)2] (dmit = 1,3-dithia-2-thioxo-4,5-dithiolate) and (nBu4N)2[Zn(dsit)2] (dsit = 1,3-dithia-2-thioxo-4,5-diselenolate) were employed as ligand precursors. The (nBu4N)2[Zn(dmit)2] complex in acetonitrile at reflux showed unexpected reactivity with [Mo3Se7Br6]2– dianion in which the inner Se atoms were replaced by S (all but the μ3-Se atom) to afford a series of mixed chalcogen [Mo3Se7–xSx(dmit)3]2– (x = 0–6) dianions. Reaction of the [Mo3S4Se3Br6]2– dianion with (nBu4N)2[Zn(dmit)2] under similar conditions also produced a mixed dmit-containing cluster formulated as [Mo3S7–xSex(dmit)3]2– (x = 0–3). The reactions were conveniently monitored by electrospray ionization mass spectrometry. The reactions of (nBu4N)2[Zn(dmit)2] and (nBu4N)2[Zn(dsit)2] with the [Mo3Se7Br6]2– dianion in dichloromethane at room temperature prevented chalcogen scrambling and allowed us to isolate the cluster salts (nBu4N)2[Mo3Se7(dmit)3] {(nBu4N)2[1]} and (nBu4N)2[Mo3Se7(dsit)3] {(nBu4N)2[2]} in analytically pure form. The crystallization of (nBu4N)2[1] from dichloromethane/diethyl ether resulted in (nBu4N)2[Mo3Se6.1S0.9(dmit)3] with partial substitution of the Seeq atoms in the cluster core. The crystal structure of (nBu4N)2[Mo3Se6.1S0.9(dmit)3] was determined by single-crystal X-ray analysis. Dianionic complexes (nBu4N)2[1], (nBu4N)2[2], and (nBu4N)2[Mo3Se7–xSx(dmit)3] (x = 0–6) were partially oxidized by iodine to afford dark semiconducting powders. These solids exhibit moderate electrical conductivities (7 × 10–2 to 6 × 10–3 S cm–1) and present antiferromagnetic exchange interactions and therefore represent new examples of magnetic Mo3Q7-based single-component conductors.