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Chalcogen‐pnictogen dihalide complexes which bear an anionic N‐heterocyclic carbene ligand with a tethered weakly coordinating borate moiety (WCA‐IDipp, WCA=B(C6F5)3, IDipp=1,3‐bis(2,6‐diisopropyphenyl)imidazolin‐2‐ylidene) were isolated and fully characterized. The metathesis reaction between the lithium salts [{(WCA‐IDipp)E}Li(toluene)] (E=S, Se) and pnictogen trihalides E′X3 (E=P, As, Sb; X=Cl, Br) afforded the complexes of the general type (WCA‐IDipp)E−E′X2 (E=S, Se; E=P, As, Sb; X=Cl, Br). In contrast, lithium chloride elimination was not observed with BiCl3 under the same reaction conditions and instead, the lithium complexes [{(WCA‐IDipp)E−BiCl3}Li(thf)4] (E=S, Se) were obtained. However, the corresponding bismuth dichloride derivatives (WCA‐IDipp)E−BiCl2 were accessible from the reaction of (WCA‐IDipp)ESiMe3 with BiCl3 upon Me3SiCl elimination. [ABSTRACT FROM AUTHOR]

The bismuth dichloride complex (WCA-IDipp)BiCl2, which bears an anionic N-heterocyclic carbene ligand with a weakly coordinating borate moiety (WCA-IDipp, WCA = B(C6F5)3, IDipp = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene), was prepared by salt metathesis reaction between BiCl3 and the lithium salt (WCA-IDipp)Li·toluene. Subsequent two-electron reduction with 1,4-bis(trimethylsilyl)-1,4-dihydropyrazine afforded the dibismuthene (WCA-IDipp)2Bi2, which displays a bismuth–bismuth double bond. [ABSTRACT FROM AUTHOR]

Several pnictogen dihalide complexes of the type (WCA‐IDipp)EX2 (E=P, As, Sb; X=Cl, Br) that bear an anionic N‐heterocyclic carbene ligand with a weakly coordinating borate moiety (WCA‐IDipp, WCA=B(C6F5)3, IDipp=1,3‐bis(2,6‐diisopropylphenyl)imidazolin‐2‐ylidene) were prepared by salt metathesis reactions between the respective pnictogen trihalides EX3 and the lithium salt (WCA‐IDipp)Li⋅toluene. Two‐electron reduction of the dihalides (WCA‐IDipp)EX2 with 1,3‐bis(trimethylsilyl)‐1,4‐dihydropyrazine or elemental magnesium afforded the dipnictenes (WCA‐IDipp)2E2, which display typical element‐element double bonds as observed in diaryldiphosphenes, ‐arsenes and ‐stibenes. To provide an insight into the factors contributing to the structural stability of the pnictogen dihalide and dipnictene compounds, quantum chemical calculations were performed at the domain‐based local pair natural orbital coupled‐cluster (DLPNO‐CCSD(T)) level. A local energy decomposition (LED) analysis of the interaction between the carbene and the pnictogen dihalide or dipnictene moiety demonstrates that London dispersion is an essential factor for the stabilization of these compounds. London calling: Several pnictogen complexes of the type (WCA‐IDipp)EX2 and (WCA‐IDipp)2E2 (E=P, As, Sb; X=Cl, Br) that bear anionic N‐heterocyclic carbene ligands with a weakly coordinating borate moiety were prepared. To provide an insight into the factors contributing to the structural stability, quantum chemical calculations were performed involving for instance Local Energy Decomposition (LED) analysis. [ABSTRACT FROM AUTHOR]