DFT studies of the σ-donor/π-acceptor properties of [SnCB₁₀H₁₁]^– and its relationship to [SnCl₃]^–, CO, PF₃, [SnB₁₁H₁₁]^2–, SnC₂B₉H₁₁, and related SnC₂B_nH_n+2 compounds

Abstract

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Diphosphaborane and Metalladiphosphaborane: Ligands for Transition‐Metal Chemistry

“…135-1398, and the range of the remaining five angles correspondingly smaller, 100-1098. Distorted tetrahedral geometries for the {MP 4 } cores have been found in other HCoP 4 [13] (and more generally HMP 4 ) [14] structures where the P ligands are similarly unidentate, including those in which the hydride ligand has been located. [15] In 1 the CoÀP cage distances, 2.038(3)-2.096(3) , are significantly shorter than CoÀP phosphine distances, 2.165(3)-2.230(3) .…”

“…The monoanionic stannacarborate [1,2-closo-SnCB 10 H 11 ] À displays intermediate behavior, having both s-donor and pacceptor properties. [4] We recently reported the structure and the first deboronation followed by metallation of the diphosphaborane 1,2closo-P 2 B 10 H 10 , [5] a compound originally prepared by Todd et al in 1989. [6] Based on the above precedents it was not clear that the neutral compounds 1,2-closo-P 2 B 10 H 10 and 3,1,2closo-MP 2 B 9 (M = transition metal) would necessarily show Lewis base behavior, and certainly no examples of these species acting in this way has previously been reported.…”

1,2‐Carbagerma‐closo‐dodecaborate as a Germanium Ligand in Coordination Chemistry – Synthesis, Structure and Reactivity

“…The B4,5 and B3,6 atoms are therefore assigned to the -13.3 ppm 11 B NMR signal. Recently, good agreements were shown between experimental and computed geometric and NMR spectroscopic data for the tin anions D and F. [16] Although there have been quantum mechanical investigations into boron clusters containing germanium and tin, [5,8,17] there has been no corresponding study reported on the germanium clusters shown in Scheme 1. Here, the optimised geometry for C is in excellent agreement with the molecular geometry determined experimentally.…”

“…Figure 2 shows the frontier orbitals for C. One exception is the π-symmetry HOMO found for D, which has a very similar energy value (only 0.01 eV difference) as its HOMO-2 with σ-symmetry. [16] Figure 2. Computed frontier orbitals for C.…”

“…[11] Clearly, C behaves like D and F in favouring the equatorial positions in trigonal-bipyramidal geometries of the type ML 3 (PPh 3 ) 2 . It has been suggested that such clusters are weak π-acceptors, [16] as shown from the LUMO of C in Figure 2, thus prefer the equatorial positions compared to the strong σ-donor PPh 3 , but the sizes of the cluster ligands are probably also responsible. Optimization of 4 with one borato ligand in the apical position gave a geometry 3.5 kcal mol -1 higher in energy than the optimized trans-phosphane geometry.…”