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White phosphorus (P4) undergoes degradation to P2 moieties if exposed to the new N,N‐bis(silylenyl)aniline PhNSi21 (Si=Si[N(tBu)]2CPh), furnishing the first isolable 2,5‐disila‐3,4‐diphosphapyrrole 2 and the two novel functionalized Si=P doubly bonded compounds 3 and 4. The pathways for the transformation of the non‐aromatic 2,5‐disila‐3,4‐diphosphapyrrole PhNSi2P22 into 3 and 4 could be uncovered. It became evident that 2 reacts readily with both reactants P4 and 1 to afford either the polycyclic Si=P‐containing product [PhNSi2P2]2P23 or the unprecedented conjugated Si=P−Si=P−Si=NPh chain‐containing compound 4, depending on the employed molar ratio of 1 and P4 as well as the reaction conditions. Compounds 3 and 4 can be converted into each other by reactions with 1 and P4, respectively. All new compounds 1–4 were unequivocally characterized including by single‐crystal X‐ray diffraction analysis. In addition, the electronic structures of 2–4 were established by Density Functional Theory (DFT) calculations. [ABSTRACT FROM AUTHOR]

New types of metal‐free white phosphorus (P4) activation are reported. While the phosphine‐silylene‐substituted dicarborane 1, CB‐SiP (CB=ortho‐C,C′‐C2B10H10, Si=PhC(tBuN)2Si, P=P[N(tBu)CH2]2), activates white phosphorus in a 2 : 1 molar ratio to yield the P5‐chain containing species 2, the analogous bis(silylene)‐substituted compound 3, CB‐Si2, reacts with P4 in the molar ratio of 2 : 1 to furnish the first isolable 1,3‐diphospha‐2,4‐disilabutadiene (Si=P−Si=P‐containing) compound 4. For the latter reaction, two intermediates having a CB‐Si2P4 and CB‐Si2P2 core could be observed by multinuclear NMR spectroscopy. The compounds 2 and 4 were characterized including single‐crystal X‐ray diffraction analyses. Their electronic structures and mechanisms were investigated by density functional theory calculations. [ABSTRACT FROM AUTHOR]

The monoatomic zero‐valent tin complex (stannylone) {[SiII(Xant)SiII]Sn0} 5 stabilized by a bis(silylene)xanthene ligand, [SiII(Xant)SiII=PhC(NtBu)2Si(Xant)Si(NtBu)2CPh], and its bis‐tetracarbonyliron complex {[SiII(Xant)SiII]Sn0[Fe(CO)4]2} 4 are reported. The stannylone 5 bearing a two‐coordinate zero‐valent tin atom is synthesized by reduction of the precursor 4 with potassium graphite. Compound 4 results from the SnII halide precursor {[SiII(Xant)SiII]SnIICl}Cl 2 or {[SiII(Xant)SiII]SnBr2} 3 through reductive salt‐metathesis reaction with K2Fe(CO)4. According to density functional theory (DFT) calculations, the highest occupied molecular orbital (HOMO) and HOMO‐1 of 5 correspond to a π‐type lone pair with delocalization into both adjacent vacant orbitals of the SiII atoms and a σ‐type lone pair at the Sn0 center, respectively, indicating genuine stannylone character. [ABSTRACT FROM AUTHOR]

In general, aromaticity can be clarified as π- and σ-aromaticity according to the type of electrons with major contributions. The traditional π-aromaticity generally describes the π-conjugation in fully unsaturated rings whereas σ-aromaticity may stabilize fully saturated rings with delocalization caused by σ-electron conjugation. Reported herein is an example of σ-aromaticity in an unsaturated three-membered ring (3 MR), which is supported by experimental observations and theoretical calculations. Specifically, when the 3 MR in cyclopropaosmapentalene is cleaved by ethane through two isodesmic reactions, both of them are highly endothermic (+29.7 and +35.0 kcal mol−1). These positive values are in sharp contrast to the expected exothermicity, thus indicating aromaticity in the 3 MR. Further nucleus-independent chemical shift and anisotropy of the current-induced density calculations reveal the nature of σ-aromaticity in the unsaturated 3 MR. [ABSTRACT FROM AUTHOR]

Highly stable five‐membered metallacycloallenes were synthesized under mild conditions. Calculations revealed that the incorporation of transition‐metal moieties relieves considerable strain and indicates a trend toward ring enlargement in the five‐membered metallacycloallenes. Conversion into six‐membered metallacycloallenes was confirmed experimentally. [ABSTRACT FROM AUTHOR]