ChemInform Abstract: Icosahedra with Slipped Vertices. The Influence of Electron Donation on the Geometry of a Stannadicarbadodecaborane (Stannacarborane).

Jutzi, Peter; Galow, Peter; Abu‐Orabi, Sultan T.; Arif, Atta M.; Cowley, A. H.; Norman, Nicholas C.

doi:10.1002/chin.198736234

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“…For example, neutral 7-and 12-vertex closo-stannacarboranes show exclusively electrophilic character and form adducts with Lewis bases such as THF or 2,2′bipyridine with "slipped" tin vertices. 24,25 In sharp contrast, closo-stannaborate [SnB 11 H 11 ] 2− shows no tendency to react with Lewis bases but can readily be methylated at the tin vertex with methyl iodide, 26 while the isoelectronic stannacarborate closo-1,2-SnCB 10 H 11 − has both σ-donor and π-acceptor properties. 27 Similarly, closo-1,2-C 2 B 8 H 10 can react both with an N-base 28 or an O-base 29 to get arachno-type structures, as verified computationally.…”

Section: ■ Introductionmentioning

confidence: 99%

Reactivity of Perhalogenated Octahedral Phospha- and Arsaboranes toward THF: A Joint Experimental/Computational Study

et al. 2022

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Reactions of the perhalogenated polyhedral pnictogenaboranes closo-1,2-Pn2B4Hal4 (Pn = P, As; Hal = Cl, Br) with Lewis bases are presently being studied with a focus on rationalizing the sites of nucleophilic attacks on clusters bearing σ-holes. These σ-holes are localized both on pnictogens and, for Hal = Br, on bromine atoms, as revealed by electrostatic potential (ESP) and intrinsic bond orbital (IBO) analyses. Surprisingly, the attack of the cyclic ether THF on closo-1,2-Pn2B4Br4 does not occur on the site with the largest positive partial charge, centered in the middle of the pnictogen–pnictogen vector. Instead, presumably promoted by the positivated bromine substituents, THF inserts into the boron–bromine bonds of the negatively charged boron atoms opposite to the pnictogen atoms to form 4-(4-bromobut-1-oxy)-closo-1,2-Pn2B4Br3 (1-PB and 1-AsB) and 4,6-(4-bromobut-1-oxy)2-closo-1,2-Pn2B4Br2 (2-PB and 2-AsB). 11B and 31P chemical shift computations at various levels support the assignments of the signals, which reflect the correctness of the molecular geometries in solutions. The Lewis-acidic perchlorinated analogues closo-1,2-P2B4Cl4, closo-1,2-As2B4Cl4, and the mixed closo-1,2-AsPB4Cl4 bear negative charges. These negative charges are revealed by the V s,max values when computing the electrostatic potentials both on the boron and the chlorine atoms. Due to this negative charge, the analogues do not react with THF unless they are heated above 66 °C, where they slowly decompose to borate esters B(OR)3 without the formation of concrete intermediates. The evaluation of 31P NMR data of 1-PB has allowed the experimental determination of the coupling constant 1 J(31P(1), 31P(2)) = |143| Hz in a closo-diphosphaborane for the first time, which agrees well with the computed value of −178 Hz. The pioneering joint experimental vs computational interpretation of 31P NMR spectra in the area of boron cluster chemistry was decisive for the structural characterization of 1-PB and 2-PB.

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Section: ■ Introductionmentioning

confidence: 99%

Reactivity of Perhalogenated Octahedral Phospha- and Arsaboranes toward THF: A Joint Experimental/Computational Study

et al. 2022

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ChemInform Abstract: Icosahedra with Slipped Vertices. The Influence of Electron Donation on the Geometry of a Stannadicarbadodecaborane (Stannacarborane).

Abstract: The stannacarborane (III), prepared by treatment of (I) with SnCl2, reacts with Py (IV) to yield the 1:2 complex (Va).

Cited by 1 publication

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Reactivity of Perhalogenated Octahedral Phospha- and Arsaboranes toward THF: A Joint Experimental/Computational Study

Reactivity of Perhalogenated Octahedral Phospha- and Arsaboranes toward THF: A Joint Experimental/Computational Study

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