Reaction of 2,6-dimesityl pyridine (L(py)) with BBr(3) leads to the spontaneous formation of the trigonal dibromoborenium cation [L(py)·BBr(2)](+)via bromide ejection. Systematic structural and computational studies, and the reactivity displayed by a closely related N-heterocyclic carbene (NHC) donor, reveal the role played by arene-borane interactions in this chemistry. [L(py)·BBr(2)](+) features a structurally characterized (albeit weak) electrostatic interaction between the borane Lewis acid and flanking arene π systems.
All in the family: Organophosphonate complexes of high‐valent vanadium are common, but their VIII analogues are few and far between. Reaction of VCl3 precursors and phosphonates under solvothermal conditions leads to a family of corresponding vanadium(III)‐based phosphonates, including the layered {VIII12(VIVO)} cluster shown in the picture (V green, P purple, O red, C black). Preliminary magnetic studies are also reported.
Eine ganze Familie: Organophosphonatkomplexe des Vanadiums in hoher Oxidationsstufe sind verbreitet, ihre VIII‐Analoga sind dagegen äußerst dünn gesäht. Aus VCl3 und Phosphonaten entsteht unter Solvothermalbedingungen eine ganze Familie entsprechender Vanadium(III)‐phosphonate, darunter der schichtförmige Cluster {VIII12(VIVO)} im Bild (V grün, P violett, O rot, C schwarz). Erste Untersuchungen zum magnetischen Verhalten werden ebenfalls beschrieben.
The ability of substituted carbazol-9-yl systems to ligate in σ fashion through the amido N-donor, or to adopt alternative coordination modes through the π system of the central five-membered ring, can be tuned by systematic variation in the steric demands of substituents in the 1- and 8-positions. The differing affinities of the two modes of coordination for hard and soft metal centres can be shown to influence not only cation selectivity, but also the redox properties of the metal centre. Thus, the highly sterically sterically demanding 1,3,6,8-tetra-tert-butylcarbazolyl ligand can be used to generate the structurally characterised amido-indium(I) complex, [{(tBu(4)carb)In}(n)], (together with its isostructural thallium counterpart) in which the metal centre interacts with the central pyrrolyl ring in η(3) fashion [d(In-N)=2.679(3) Å; d(In-C)=2.819(3), 2.899(3) Å]. By contrast, the smaller 3,6-di-tert-butylcarbazolyl system is less able to restrict the metal centre from binding at the anionic nitrogen donor in the plane of the carbazolyl ligand (i.e. in σ fashion). Analogous chemistry with In(I) precursors therefore leads to disproportionation to the much harder In(II) [and In(0)], and the formation of the mixed-valence product, [In(2){In(2)(tBu(2)carb)(6)}], a homoleptic molecular [In(4)(NR(2))(6)] system. This chemistry reveals a flexibility of ligation for carbazolyl systems that contrasts markedly with that of the similarly sterically encumbered terphenyl ligand family.
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