Structural, Spectroscopic and Computational Examination of the Dative Interaction in Constrained Phosphine–Stibines and Phosphine–Stiboranes

Abstract

A series of phosphine-stibine and phosphine-stiborane peri-substituted acenaphthenes containing all permutations of pentavalent groups -SbCln Ph4-n (5-9), as well as trivalent groups -SbCl2 , -Sb(R)Cl, and -SbPh2 (2-4, R=Ph, Mes), were synthesised and fully characterised by single crystal diffraction and multinuclear NMR spectroscopy. In addition, the bonding in these species was studied by DFT computational methods. The P-Sb dative interactions in both series range from strongly bonding to non-bonding as the Lewis acidity of the Sb acceptor is decreased. In the pentavalent antimony series, a significant change in the P-Sb distance is observed between -SbClPh3 and -SbCl2 Ph2 derivatives 6 and 7, respectively, consistent with a change from a bonding to a non-bonding interaction in response to relatively small modification in Lewis acidity of the acceptor. In the Sb(III) series, two geometric forms are observed. The P-Sb bond length in the SbCl2 derivative 2 is as expected for a normal (rather than a dative) bond. Rather unexpectedly, the phosphine-stiborane complexes 5-9 represent the first examples of the σ(4) P→σ(6) Sb structural motif.

Continuum in the X‐Z‐‐‐Y weak bonds: Z= main group elements

“…His analysis shed light in to the existence of weak boron‐bonds, though the continuum nature of 2‐centre 2‐electron and Z‐bond was not obvious. Very recently Chalmers et al, observed the strong‐bond to dative‐bond and further to no‐bond interactions in constrained P‐‐‐Sb systems as the Lewis acidity of the acceptor decreases . Similar observations can be made about the course of atom abstraction reactions, chemical reaction mechanisms or nucleophilic substitution reactions published in recent times.…”

Fluorinated antimony(v) derivatives: strong Lewis acidic properties and application to the complexation of formaldehyde in aqueous solutions

“…Short P–Sb separations have also been observed in derivatives in which the two moieties are linked by a peri -naphthalene linker such as 5-(Ph 2 P)–6-(Cl 2 Sb)–Ace (2.808(1) Å) or 5-( i Pr 2 P)–6-(Cl 2 Ph 2 Sb)–Ace (2.9925(8) Å, Ace = acenaphthylene). 60 Although these P–Sb distances are comparable to those measured in 5 and 7 , it can be expected that the strain imposed by the use of the ortho -phenylene backbone will fragilize this linkage, opening the door for reactivity in the P/Sb pocket.…”

Size Matters: Synthesis of Group 13 Metal‐Substituted Dipnictanes by E‐C Bond Homolysis

“…Deuterated benzene was dried with activated molecular sieves (4 Å) and degassed prior to use. Starting materials LAl, [ 13 ] LGa, [ 14 ] LIn, [ 15 ] PhAsCl 2 , [ 41 ] PhSbCl 2 , [ 42 ] and KCp* [ 43 ] were prepared according to literature procedures. NMR spectra ( δ in ppm) were recorded using a Bruker Avance DPX 300 ( 1 H 300.1 MHz, 13 C{ 1 H} 75.5 MHz) or a Bruker Avance Neo 400 ( 1 H 400.1 MHz, 13 C{ 1 H} 100.6 MHz) spectrometer and were referenced to internal C 6 D 5 H ( 1 H δ = 7.16, 13 C δ = 128.06) or C 6 D 5 CD 2 H ( 1 H δ = 2.08, 13 C δ = 20.43).…”