Control of Λ- and Δ-Isomerization of the Atrane Cages in Group XIV Metallatranes by Chiral Axial Substituents

Mononuclear Pseudostannatranes Possessing Unsymmetrical [4.4.3.01,5]Tridecane Cage: Experimental and Theoretical Aspects of Reverse Kocheshkov Reaction in Phenyl Pseudostannatrane

The synthetic protocols, structural aspects, and spectroscopic aspects of mononuclear pseudostannatranes possessing a [4.4.3.0^1,5]tridecane cage have been reported. A tripodal ligand N(CH₂CH₂OH){CH₂(2-t-Bu-4-Me-C₆H₂OH)}₂ (H₃L) having unsymmetrical arms was reacted with n-butyltrichlorostannane, phenyltrichlorostannane, and tin tetrachloride under different solvent systems to obtain pseudostannatranes (1-3). The reaction of n-butyltrichlorostannane and the ligand in CH₃OH/Na/THF yielded an aqua complex of pseudostannatrane [LSnBu(H₂O)] (1_a), which was crystallized as its acetone solvate (i.e 1_a·Me₂CO). However, the same reactants yielded methanol complex [LSnBu(CH₃OH)] (1_b) when the reaction was carried out in the NaOCH₃/C₂H₅OH system. Similarly, the reaction of phenyltrichlorostannane and the ligand under these solvent systems yielded pseudostannatranes, i.e., an aqua complex [LSnPh(H₂O)] (2_a) and a methanol complex [LSnPh(CH₃OH)] (2_b) (where 2_a was crystallized as 2_a·Me₂CO). The reaction of tin tetrachloride and the ligand in the Et₃N/THF system resulted in the formation of pseudostannatrane [LHSnCl₂] (3). A similar product was isolated as its triethylamine solvate (3·NEt₃) due to the disproportion reaction when PhSnCl₃ was reacted with the ligand in the Et₃N/C₆H₅CH₃ system, which demonstrates the first report on the reverse Kocheshkov reaction in pseudostannatranes. The experimental findings on the formation of 3·NEt₃ due to the reverse Kocheshkov reaction have been corroborated with ¹¹⁹Sn NMR spectroscopy and density functional calculations that provide insightful information about the underlying details of the reaction route.

Crystallographic and spectroscopic characterization of racemic Mosher's Acid

Mosher’s Acid (systematic name: 3,3,3-tri­fluoro-2-meth­oxy-2-phenyl­propanoic acid) is a carb­oxy­lic acid that when resolved can be employed as a chiral derivatizing agent. The two independent mol­ecules in the asymmetric unit form a non-centrosymmetric homochiral dimer via inter­molecularly hydrogen-bonded head-to-tail dimers with graph-set notation (8).

The title compound, C₁₀H₉F₃O₃, represents the structure of racemic Mosher’s Acid (systematic name: 3,3,3-tri­fluoro-2-meth­oxy-2-phenyl­propanoic acid), a carb­oxy­lic acid that when resolved can be employed as a chiral derivatizing agent. The compound contains a carb­oxy­lic acid group, a meth­oxy group and a tri­fluoro­methyl substituent on an asymmetric benzylic carbon atom. The two independent mol­ecules in the asymmetric unit form a non-centrosymmetric homochiral dimer via inter­molecularly hydrogen-bonded head-to-tail dimers with graph-set notation R₂²(8) and donor–acceptor hydrogen-bonding distances of 2.6616 (13) and 2.6801 (13) Å.

Tricyclic tin(iv) cages: synthetic aspects and intriguing features of stannatranes and pseudostannatranes

This perspective summarizes various synthetic routes of stannatranes and pseudostannatranes along with their interesting features, such as appearance of satellites in their NMR spectra, cluster formation upon hydrolysis and exchange reactions.