Choice of computational protocol for carbon-lithium spin-spin coupling constants 1 JCLi

In this work, we tested various computational schemes for calculations of ¹ J_CLi constants with a high accuracy. On the example of six organolithium reagents (phenyllithium monomer and dimer, monomer s-butyllithium, monomers of 1- and 2-lithionaphthalenes, and a methyllithium tetramer), the following aspects are discussed: (i) the role of a model system geometry, (ii) influence of solvent effects, and (iii) the choice of a functional and basis set. Practical recommendations for calculation of ¹ J_CLi with an accuracy ±2 Hz are formulated.

Monodentate coordination of the normally chelating chiral diamine (R,R)-TMCDA

After isolating an unusual binuclear, but monosolvated NaHMDS complex [{(R,R)-TMCDA}·(NaHMDS)₂]_∞ which polymerises via intermolecular electrostatic NaMe_HMDS interactions, further (R,R)-TMCDA was added to produce the discrete binuclear amide [{κ²-(R,R)-TMCDA}·(NaHMDS)₂{κ¹-(R,R)-TMCDA}], whose salient feature is the unique monodentate coordination of one of the chiral diamine ligands.

Crystal structures of di-aquadi-μ-hydroxido-tris-[tri-methyl-tin(IV)] diformatotri-methyl-stannate(IV) and di-μ-hydroxido-tris-[tri-methyl-tin(IV)] chloride monohydrate

The title compounds, [Sn3(CH3)9(OH)2(H2O)2][Sn(CH3)3(CHO2)2] (1) and [Sn3(CH3)9(OH)2]Cl·H2O (2), are partially condensed products of hydrolysed tri-methyl-tin chloride. In the structures of 1 and 2, short cationic tris-tannatoxanes (C9H29O2Sn3) are bridged by a diformatotri-methyl-tin anion or a chloride anion, respectively. Hydrogen bridges are present and supposedly stabilize these structures against further polymerization to the known polymeric tri-methyl-tin hydroxide. Especially noteworthy is that the formate present in this structure was formed from atmospheric CO2.

Crystal structure of di-benzyl-dimethyl-silane

In the title compound, C16H20Si, a geometry different from an ideal tetra-hedron can be observed at the Si atom. The bonds from Si to the benzylic C atoms [Si-C = 1.884 (1) and 1.883 (1) Å] are slightly elongated compared to the Si-Cmeth-yl bonds [Si-C = 1.856 (1) and 1.853 (1) Å]. The Cbenz-yl-Si-Cbenz-yl bond angle [C-Si-C = 107.60 (6)°] is decreased from the ideal tetra-hedral angle by 1.9°. These distortions can be explained easily by Bent's rule. In the crystal, mol-ecules inter-act only by van der Waals forces.