A study of chirality in bis(1,2-dimethoxyethane-kappa2O,O')sodium bis(tri-tert-butoxysilanethiolato-kappa2O,S)sodate.

This work presents an analysis of self-assembly of a complex molecule from simpler ions, some of which are asymmetric, and is an example of a sodium silanethiolate. The tri-tert-butoxysilanethiolate anion has two helical conformers (P and M), so aggregation of silanethiolates can proceed with recognition of chirality. Alkali metal silanethiolates can form cyclic solvated oligomers (e.g. dimers) or complexes such as sodates with anions of general formula R2Na(-). We note that all known sodates (and lithiates) contain both ligands of the same helicity in the anion, whereas in the dimers the metal atoms are coordinated by silanethiolate ligands of different helicity. The title compound, a new example of a sodate, [Na(C4H10O2)2][Na(C12H27O3SSi)2] or [Na{((t)BuO)3SiS}2][Na(DME)2] (DME is 1,2-dimethoxyethane), is built up of separate ion pairs with no significant interactions. The anion is formed from an Na atom O,S-chelated by two silanethiolate ligands of the same helicity (both P or both M), while the cation contains an Na atom solvated by two DME molecules. Because the structure is centrosymmetric, equal numbers of both conformational enantiomers are present in the crystal lattice.