Heavy Chains: Synthesis, Reactivity and Decomposition of Interpnictogen Chains with Terminal Diaryl Bismuth Fragments

In this work, we report the preparation of multiple interpnictogen chain compounds with three consecutive pnictogen atoms and terminal Ar₂ Bi fragments (Ar=Ph, Mes). Symmetrical compounds of the form Ar₂ Bi-E(tBu)-Bi₂ Ar (1: Ar=Ph, E=P; 2: Ar=Ph, Mes, E=As) as well as ternary interpnictogen compounds of the form Ar₂ Bi-E¹ (tBu)-E² tBu₂ (Ar=Ph, Mes; 4: E¹ =P, E² =As; 5: E¹ =P, E² =Sb; 6: E¹ =As, E² =P) were prepared. The decomposition in solution at room temperature and under the influence of light was studied for compounds 1-6. The reactivity of 1_Ph and 2_Ph with the small N-heterocyclic carbene 1,3,4,5-tetramethylimidazol-2-ylidene (Me₂ IMe) was also studied. In the case of 1_Ph , the formation and consecutive decomposition of Me₂ IMe=PtBu (8) was observed in solution. Hence, it was shown that 1_Ph can react as a "masked phosphinidene". In the case of 2_Ph , no reaction with Me₂ IMe was observed. All isolated compounds were analysed by NMR and IR spectroscopy, mass spectrometry, elemental analysis and single-crystal X-ray diffraction.

Heavier element-containing aromatics of [4n+2]-electron systems

While the implication of the aromaticity concept has been dramatically expanded to date since its emergence in 1865, the classical [4n+2]/4n-electron counting protocol still plays an essential role in evaluating the aromatic nature of compounds. Over the last few decades, a variety of heavier heterocycles featuring the formal [4n+2] π-electron arrangements have been developed, which allows for assessing their aromatic nature. In this review, we present recent developments of the [4n+2]-electron systems of heavier heterocycles involving group 13-15 elements. The synthesis, spectroscopic data, structural parameters, computational data, and reactivity are introduced.

Bismuthanylstibanes

Thermally-robust bismuthanylstibanes are prepared in a one-step, high yield reaction, providing the first examples of neutral Bi-Sb σ-bonds in the solid state. DFT calculations indicate that the bis(silylamino)naphthalene scaffold is well-suited for supporting otherwise labile bonds. The reaction chemistry of the Bi-Sb bond is debuted by showing fission using NH₃BH₃ and insertion of a sulfur atom, the latter providing the first example of a Bi-S-Sb motif.

New synthetic strategies leading to [RNPNR]- anions and the isolation of the [P(Nt-Bu)3]3- trianion

New and straightforward synthetic paths for the syntheses of [RNPNR]- anions (R = t-Bu (1) or CPh3 (6)) in the form of their tmeda- or thf-coordinated lithium salts are described. The attempts to isolate the sodium analogue [(Ph3CNPNCPh3)Na·(thf)x] (8) remained unsuccessful probably due to its high reactivity although its formation in the reaction of the parent cis-[(Ph3CNP)2(Ph3CNH)2] (5) with 2 eq. of sodium naphthalenide was corroborated by NMR spectroscopy. Importantly, when an excess of sodium naphthalenide was used in the reaction with 5, [(Ph3C)Na(thf)3] (9) was obtained along with a complex mixture of other by-products indicating the cleavage of the C-N bond in the starting material. Furthermore, the synthesis and the structural characterization of the [P(Nt-Bu)3]3- trianion as its trilithium salt [P(Nt-Bu)3Li3]2 (10) has been successfully achieved.

Trapping of transient, heavy pnictogen-centred biradicals

The heavy biradicals [E(μ-NTer)]₂ (E = Sb, Bi) were generated in situ and trapped by a formal [2 + 2] addition reaction with tolan (Ph–CC–Ph).

Group 15 biradicals: synthesis and reactivity of cyclobutane-1,3-diyl and cyclopentane-1,3-diyl analogues

Synthesis, structure and reactivity of cyclobutane-1,3-diyl and cyclopentane-1,3-diyl analogues are discussed along with their application as molecular switches or reagents to activate or trap small molecules with single or multiple bonds.

Synthesis of a Molecule with Four Different Adjacent Pnictogens

The synthesis of a molecule containing four adjacent different pnictogens was attempted by conversion of a Group 15 allyl analogue anion [Mes*NAsPMes*](-) (Mes*=2,4,6-tri-tert-butylphenyl) with antimony(III) chloride. A suitable precursor is Mes*N(H)AsPMes* (1) for which several syntheses were investigated. The anions afforded by deprotonation of Mes*N(H)AsPMes* were found to be labile and, therefore, salts could not be isolated. However, the in situ generated anions could be quenched with SbCl3 , yielding Mes*N(SbCl2 )AsPMes* (4).