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Bis(carbazolide) complexes M[3,6‐tBu2‐1,8‐(RC≡C)2Carb]2(THF)n (R=SiMe3, n=0, M=Ca, Yb; R=Ph, n=1, M=Ca, Yb; n=0, M=Yb) were synthesized through transamination reaction of M[N(SiMe3)2]2(THF)2 with two molar equivalents of carbazoles. The complexes feature M(η2‐C≡C)4 structural motif composed of M(II) ions encapsulated by four acetylene fragments due to atypical for alkaline‐ and rare‐earth metals η2‐interactions with triple C≡C bond. This interaction is evidenced experimentally by X‐ray diffraction, Raman spectroscopy in the solid state and by NMR‐spectroscopy in the solution. According to QTAIM analysis there are 4 bond critical points (3;−1) between the metal atom and each of the triple bonds, which are connected by a strongly curved, almost T‐shaped bond pathway. [ABSTRACT FROM AUTHOR]

Diene rhodium complexes are important catalysts in modern organic synthesis. Herein, we report a new approach to such complexes with the uncommon planar chirality. The synthesis is achieved by face‐selective coordination of the prochiral 2,5‐disubstituted‐1,4‐benzoquinones (R2‐Q) with rhodium precursors containing the chiral auxiliary ligand S‐salicyl‐oxazoline (S‐Salox). Such coordination leads to the formation of (R,R‐R2‐Q)Rh(S‐Salox) complexes in high yields and with exceptional diastereoselectivity (d. r.>20 : 1). Subsequent replacement of the auxiliary ligand provides various benzoquinone rhodium complexes with retention of the planar chirality. Combined theoretical and experimental studies show that due to their electron‐withdrawing nature benzoquinones bind metals stronger than the related 1,4‐cyclohexadiene, but weaker than other common diene ligands, such as cyclooctadiene. [ABSTRACT FROM AUTHOR]

In the original article, Scheme 5 describes the reaction of O-Boc-phenylhydroxamic acid with a mixture of alkenes, Scheme 6 describes the reaction of O-Boc- and O-Piv-phenylhydroxamic acid with styrene. For example, reaction of B 1 a b with an equimolar mixture of allyl alcohol, styrene and myrcene proceed selectively in the presence of the catalyst B 5 b to give 4-CH SB 2 sb OH-substituted product B 4 e b in 89 % yield (Scheme 5). Indeed, we observed that the reaction of O-Boc-phenylhydroxamic acid B 1 a b with styrene in the presence of the classical catalyst [Cp*RhCl SB 2 sb ] SB 2 sb gives only the 3-benzylisoindolin-1-one B 4 p b , while similar reaction of O-pivaloyl-phenylhydroxamic acid B 1 b b produced the 3-substituted structural isomer B 3 p b (Scheme 6). [Extracted from the article]

A comparative study of chemical bonding peculiarities in 1,2,4,5-tetrazine was carried out to test the performance of a recently developed invariom approach against a conventional charge density analysis of high-resolution X-ray diffraction data and quantum chemical calculations within the plane-wave functional theory. The amazing similarity between the intermolecular features thus obtained for this van der Waals crystal showed the invariom approximation to now emerge as a fast and convenient way towards reliable description of weak intermolecular interactions. [ABSTRACT FROM AUTHOR]