Synthesis and characterization of Mo and W compounds containing aminothiolate ligand for disulfide materials

Diverse Post-Metathesis Reactivities of Mixed Amido-Isothiocyanato Molybdenum Complexes

Attempts to prepare mixed isothiocyanato-bis(imido) MoVI complexes led to the discovery of post-metathesis rearrangements toward three distinct products (1-3), which feature the NCS-derived chelators [N(NMe2)CS]2- (L1 in dinuclear 1 and 2) and [N(SiMe3)(NMe2)CS]- (L2 in mononuclear 3). Notably, the preparation of bidentate ligand L1 and its coordination chemistry are unprecedented. Together with computational studies, it is proposed that the putative "mono-substituted" intermediate [Mo(NtBu)2(NMe2)(NCS)] serves as the common starting point for the observed molecular transformations. Construction of the [Mo(NtBu)2(NCS)2] core was ultimately possible in the presence of additional stabilizing donors (THF or PMe3), which yielded the complexes [Mo(NtBu)2(NCS)2(THF)2] (4) and [Mo(NtBu)2(NCS)2(PMe3)2] (5).

Tin(II) Aminothiolate and Tin(IV) Aminothiolate Selenide Compounds as Single-Source Precursors for Tin Chalcogenide Materials

Tin aminothiolate compounds Sn^II(dmampS)₂ (1) and Sn^IV(dmampS)₂Se (2), where dmampS = 1-(dimethylamino)-2-methylpropane-2-thiolate, were synthesized. The molecular structures of 1 and 2 reveal a seesaw and distorted trigonal-bipyramidal geometry, respectively. The ¹H NMR spectrum of 1 shows two types of resonances for the methyl groups of the α-carbon, methyl groups of the amino groups, and methylene groups at room temperature. On the other hand, the ¹H NMR spectrum of 2 exhibits a single resonance for each of these groups. According to variable-temperature ¹H NMR analysis, each of these two types of resonances occurring at relatively low temperatures (under 223 K for 1 and under 333 K for 2) are merged as a single resonance with increasing temperature. By using thermogravimetric and thermal decomposition analyses, the residual materials of compounds 1 and 2 are confirmed to be SnS and SnSSe, respectively. Compound 1 was subjected to a metal-organic chemical vapor deposition process, which allowed for the deposition of a dense and well-faceted orthorhombic phase SnS thin film on a SiO₂/Si substrate with ∼200 nm thickness.

Two-dimensional WS2 nanoribbon deposition by conversion of pre-patterned amorphous silicon

We present a method for area selective deposition of 2D WS₂ nanoribbons with tunable thickness on a dielectric substrate. The process is based on a complete conversion of a pre-patterned, H-terminated Si layer to metallic W by WF₆, followed by in situ sulfidation by H₂S. The reaction process, performed at 450 °C, yields nanoribbons with lateral dimension down to 20 nm and with random basal plane orientation. The thickness of the nanoribbons is accurately controlled by the thickness of the pre-deposited Si layer. Upon rapid thermal annealing at 900 °C under inert gas, the WS₂ basal planes align parallel to the substrate.