Synthesis of Tetrahedranes Containing the Unique Bridging Hetero‐Dipnictogen Ligand EE′ (E ≠ E′=P, As, Sb, Bi)

Abstract

In order to improve and extend the rare class of tetrahedral mixed main group transition metal compounds, a new synthetic route for the complexes [{CpMo(CO)2}2(μ,η2:η2‐PE)] (E=As (1), Sb (2)) is described leading to higher yields and a decrease in reaction steps. Via this route, also the so far unknown heavier analogues containing AsSb (3 a), AsBi (4) and SbBi (5) ligands, respectively, are accessible. Single crystal X‐ray diffraction experiments and DFT calculations reveal that they represent very rare examples of compounds comprising covalent bonds between two different heavy pnictogen atoms, which show multiple bond character and are stabilised without any organic substituents. A simple one‐pot reaction of [CpMo(CO)2]2 with ME(SiMe3)2 (M=Li, K; E=P, As, Sb, Bi) and the subsequent addition of PCl3, AsCl3, SbCl3 or BiCl3, respectively, give the complexes 1–5. This synthesis is also transferable to the already known homo‐dipnictogen complexes [{CpMo(CO)2}2(μ,η2:η2‐E2)] (E=P, As, Sb, Bi) resulting in higher yields comparable to those in the literature reported procedures and allows the introduction of the bulkier and better soluble Cp′ (Cp′=tert butylcyclopentadienyl) ligand.

Structural diversity of mixed polypnictogen complexes: dicationic E2E′2 (E ≠ E′ = P, As, Sb, Bi) chains, cycles and cages stabilized by transition metals

“…The 31 P{ 1 H} NMR spectrum of 2 also reveals a sole singlet at δ = 35.0 ppm, which again is shifted to higher field by 60 ppm in comparison to the starting material B ( δ = 98.8 ppm). 18 This verifies the suggestion that, analogously to 1 , a P–P coupled dicationic product is formed ( Scheme 2 ).…”

“…Mo 2 SbBi also shows an additional small oxidation wave at +0.05 V, which can be attributed to small amounts of Mo 2 Sb 2 , which are formed as trace impurities during its synthesis. 18 …”

“…It is very remarkable that the arsenic and antimony atoms within the cycle are bound in an alternating fashion. 19 The intratetrahedral As–Sb bonds are elongated compared to free C by 0.1 to 0.2 Å, 18 but are still in the range of a single bond. The Mo–Mo bonds are widened up in the same manner.…”

“…They are now accessible via a simple procedure in high yields, which makes further reactivity studies feasible. 18 C–E feature the very first covalent bonds between two different heavy pnictogen atoms that do not possess organic substituents. Hence, A–E should serve as excellent precursors for the formation of unprecedented extended hetero-polypnictogen frameworks upon oxidation.…”

Binary interpnictogen compounds bearing diaryl bismuth fragments bound to all lighter pnictogens

“…22 Moreover, Scheer and co-workers reported about compounds consisting of [Mo] 2 BiE-tetrahedra ([Mo] = [Mo(CO) 2 Cp]; E = Sb and As) where a bond order of around 1.5 is ascribed for the Bi-E bond (Scheme 1, F). 23 Herein, we report the synthesis and characterisation of multiple interpnictogen compounds prepared from diphenyl or dimesityl halido bismuthanes, featuring Bi-E bonds to all lighter pnictogens, including compounds with rare arsenicand antimony-bismuth bonds (E = N, P, As and Sb). All isolated compounds were characterised by NMR and IR spectroscopy, mass spectrometry and elemental analysis.…”