Single-Crystal Structures of Benzenehexathiol and Its Disulfide Forms

Oligothiols are useful as building blocks in the construction of disulfide-based macrocycles and polymers or as ligands for coordination polymers. Above all, benzenehexathiol (BHT) is a particularly important molecule, as it is used to construct conductive two-dimensional MOFs. Despite the desire to clarify its structure and isolate it to high purity, the chemical instability of BHT has hampered single-crystal X-ray structure analysis of intact BHT. In addition, the synthesis of discrete disulfide molecules of BHT has not been reported. Here, we succeed in obtaining the single crystals of intact BHT, which is analyzed by single crystal X-ray structure analysis. Furthermore, the structures of a group of molecules with intermolecular disulfide bonds (BHT·4im and BHT2·2TBA, im = imidazole, TBA = tetrabutylammonium cation) obtained by processing BHT in the presence of bases are determined.

Synthesis and characterization of a family of thioether-dithiolate-bridged heteronuclear iron complexes

The thioether-dithiolate-bridged heterotrinuclear complexes [Cp*Fe(μ-1_k³SSS':2_k²SS-tpdt)M(μ-2_k²SS:3_k³SSS'-tpdt)FeCp*][PF₆]₂ (Cp* = η⁵-C₅Me₅; tpdt = S(CH₂CH₂S)₂; 2, M = Co; 3, M = Ni; 4, M = Pd) have been prepared by a reaction of [Cp*Fe(η³-tpdt)] (1) with complexes CoCl₂, NiCl₂(PPh₃)₂, and PdCl₂(PPh₃)₂, respectively. Similarly, treatment of complex 1 with CuCl(PPh₃) or AgPF₆ afforded two heterotrinuclear complexes, [Cp*Fe(μ-1_k³SSS':2_k²SS-tpdt)M(μ-2_k²SS:3_k³SSS'-tpdt)FeCp*][PF₆] (5, M = Cu; 6, M = Ag), while reaction of 1 with the complex AuCl(PPh₃) gave a heterobinuclear complex, [Cp*Fe(μ-1_k³SSS':2_k¹S-tpdt)Au(PPh₃)][PF₆] (7). These complexes have been spectroscopically and crystallographically characterized. An X-ray diffraction analysis showed that complexes 2, 3, 5, and 6 feature a heterometal center binding four sulfur atoms of two tpdt ligands with a cis orientation. However, in the Pd-containing complex 4, two tpdt ligands are arranged in a trans configuration. The μ_eff data and EPR results indicate that complexes 2, 4, 5, 6, and 7 are paramagnetic and only complex 3 is diamagnetic. Electrochemical experiments on these heteronuclear clusters were performed at room temperature. Discrepancy of the redox couples in the CV plots of these complexes indicates different one-electron transfer processes.

Coordination Programming of Two-Dimensional Metal Complex Frameworks

Since the discovery of graphene, two-dimensional materials with atomic thickness have attracted much attention because of their characteristic physical and chemical properties. Recently, coordination nanosheets (CONASHs) came into the world as new series of two-dimensional frameworks, which can show various functions based on metal complexes formed by numerous combinations of metal ions and ligands. This Feature Article provides an overview of recent progress in synthesizing CONASHs and in elucidating their intriguing electrical, sensing, and catalytic properties. We also review recent theoretical studies on the prediction of the unique electronic structures, magnetism, and catalytic ability of materials based on CONASHs. Future prospects for applying CONASHs to novel applications are also discussed.

π-Conjugated trinuclear group-9 metalladithiolenes with a triphenylene backbone

Previously, we synthesized π-conjugated trinuclear metalladithiolene complexes based on benzenehexathiol (J. Chem. Soc., Dalton Trans.1998, 2651; Dalton Trans.2009, 1939; Inorg. Chem.2011, 50, 6856). Here we report trinuclear complexes with a triphenylene backbone. A reaction with triphenylenehexathiol and group 9 metal precursors in the presence of triethylamine gives rise to trinuclear complexes 9-11. The planar structure of 11 is determined using single crystal X-ray diffraction analysis. The ligand-to-metal charge transfer bands of 9-11 move to longer wavelengths compared with those of mononuclear 12-14. Electrochemical measurements disclose that the one-electron and two-electron reduced mixed-valent states are stabilized thermodynamically. UV-vis-NIR spectroscopy for the reduced species of 9 identifies intervalence charge transfer bands for 9(-) and 9(2-), substantiating the existence of electronic communication among the three metal nuclei. These observations prove that the triphenylene backbone transmits π-conjugation among the three metalladithiolene units.

Unprecedented tris-phosphido-bridged triangular clusters with 42 valence electrons. Chemical, electrochemical and computational studies of their formation and stability

This paper presents the synthesis and structural characterization of the unprecedented tris-phosphido-bridged compounds Pt3(μ-PBu(t)2)3X3 (X = Cl, Br, I), having only 42 valence electrons, while up to now analogous clusters typically have 44e(-). The new species were obtained by an apparent bielectronic oxidation of the 44e(-) monohalides Pt3(μ-PBu(t)2)3(CO)2X with the corresponding dihalogen X2. Their X-ray structures are close to the D3h symmetry, similarly to the 44e(-) analogues with three terminal carbonyl ligands. The products were also obtained by electrochemical oxidation of the same monohalides in the presence of the corresponding halide. In a detailed study on the formation of Pt3(μ-PBu(t)2)3I3, the redox potentials indicated that I2 can only perform the first monoelectronic oxidation but is unsuited for the second one. Accordingly, the 43e(-) intermediate [Pt3(μ-PBu(t)2)3(CO)2I](+) was ascertained to play a key role. Another piece of information is that, together with the fully oxidized product Pt3(μ-PBu(t)2)3I3, the transient 44e(-) species [Pt3(μ-PBu(t)2)3(CO)3](+) is formed in the early steps of the reaction. In order to extract detailed information on the formation pathway, involving both terminal ligand substitutions and electron transfer processes, a DFT investigation has been performed and all the possible intermediates have been defined together with their associated energy costs. The profile highlights many important aspects, such as the formation of an appropriate couple of 43e(-) intermediates having different sets of terminal coligands, and suitable redox potentials for the transfer of one electron. Optimizations of 45e(-) associative intermediates in the ligand substitution reactions indicate their possible involvement in the redox process with reduction of the overall energy cost. Finally, according to MO arguments, the unique stability of the 42e(-) phosphido-bridged Pt3 clusters can be attributed to the simultaneous presence of three terminal halides.