The synthesis of the Lewis base stabilized monomeric parent compound of stibanylboranes, "H2 Sb-BH2 ", is reported. Through a salt metathesis route, the silyl-substituted compounds (Me3 Si)2 Sb-BH2 ⋅LB (LB=NMe3 , NHC(Me) ) were synthesized as representatives of derivatives with a Sb-B σ bond. Under very mild conditions, they could be transformed into the target compounds Me3 N⋅H2 B-HSb-BH2 ⋅NMe3 and H2 Sb-BH2 ⋅NHC(Me) , respectively. The products were characterized by X-ray structure analysis, NMR spectroscopy, IR spectroscopy, and mass spectrometry. DFT calculations give further insight into the stability and bonding of these unique compounds.

The synthesis and properties of the diphenyl-substituted arsanylborane Ph AsBH SMe (1) and Ph AsBH NMe (2) stabilized by a Lewis base (LB) were reported. These compounds were obtained by reaction of KAsPh with IBH -LB (LB=SMe , NMe ). Compounds 1 and 2 were used as starting materials for oligomeric/ polymeric arsinoboranes. The neutral species, H B-Ph AsBH NMe (3) and Br B-Ph AsBH NMe (4), were synthesized by reaction with H B and Br B, respectively. Upon reaction with IBH -LB (LB=SMe , NMe ), the cationic oligomeric group-13/15-based compounds [(Me NBH AsPh BH NMe )]I (5) and [H B(Ph AsBH NMe ) ]I (6) were obtained. All compounds were completely characterized. In addition, the oxidation of Ph AsBH NMe with chalcogens was studied. The sulfur Ph As(S)BH NMe (7 b) and selenium Ph As(Se)BH NMe (7 c) oxidation products were both isolated and fully characterized, whereas the bis(trimethylsilyl)peroxide oxidated arsinoborane Ph As(O)BH NMe (7 a) was not stable enough and could only be characterized in solution. DFT computations supported the decomposition pathway of this compound.

We report on depolymerization reactions of poly(phosphinoboranes). The cleavage of the polymers [H PBH ] (2 a), [tBuHPBH ] (2 c), [PhHPBH ] (2 e) and the oligomer [Ph PBH ] (2 b), with strong Lewis bases (LBs), in particular with NHCs, leads to the corresponding monomeric phosphanylboranes R R PBH LB. It is observed that the depolymerization depends on the strength and stability of the LBs as well as on the substitution pattern of the poly(phosphinoboranes). The solid state structures of the monomeric phosphinoboranes H PBH NHC (NHC=N-heterocyclic carbene) (4 a), H PBH NHC (5 a) and tBuHPBH NHC (4 c) were determined. DFT calculations support the experimentally observed reaction behavior.

The elemental chalcogens sulfur, selenium, tellurium and bis(trimethylsilyl)peroxide as an oxygen source are applied for the oxidation of the phosphanylboranes Ph P-BH ⋅NMe (1) and tBuHP-BH ⋅NMe (2). The corresponding monooxidation products Ph P(X)-BH ⋅NMe (X=O-Te, 3 a-d) and tBuHP(X)-BH ⋅NMe (X=O-Te, 4 a-d) were obtained in good yields and comprehensively characterized by single crystal X-ray structure analysis, NMR, IR spectroscopy and mass spectrometry. The first oxidation step proceeds very selectively for all chalcogenides. For the tBu derivative, a further oxidation can be realised with O , S and Se yielding tBu(HX)P(X)-BH ⋅NMe (X=O, S, Se, 5 a-c). The telluride compounds presented herein are the first examples of neutral Te-substituted phosphanylboranes.

We report on the synthesis and characterization of mixed pnictogenylboranes. The substitution of the Lewis base SMe in (OC) W-PH BH -SMe (2) by different pnictogenylboranes ER BH -LB (E=P, As, Sb) leads to the Lewis acid/base stabilized butane analogue (OC) W-PH BH ER BH -LB (3 a, b: E=P; R=H, SiMe ; LB=NMe ; 4 a, b: E=As; R=H, SiMe ; LB=NMe ; 5: E=Sb; R=SiMe ; LB=NHC ). All of these compounds were characterized by single-crystal X-ray structure analysis, mass spectrometry, NMR, and IR spectroscopy. In addition, the very unstable phosphanylborane chain PH BH PH BH -NMe (1) was synthesized. DFT calculations provide insight into the thermodynamics of these reactions.