The first bona-fide sodium complex of hydrotris(methimazolyl)borate: An example of sodium exhibiting a preference for sulfur over oxygen

Abstract

The synthesis and structure of two related sodium complexes are reported which demonstrate that sulfur can preferentially complex to sodium irrespective of the presence of more apposite donor species such as DMF.

S‐Alkylation of Soft Scorpionates

“…Crystallographic analysis confirms the transfer of alkyl groups to the sulfur atom of the thione moiety (Figure 1). The analysis also shows that, in the solid state, the orientation of the heterocyclic rings is such that the newly formed thioether moieties are syn with respect to the BH group (that is, above the plane defined by the three donor nitrogen atoms (N1) bonded to the BH group), a structural feature that is also observed in [Tm Me ] − itself 5–9 …”

“…An initial analysis of the four possible conformations of the Tm Me anion itself (obtained by rotations of the heterocycles around the BN bonds) suggests that the 2:1 form (Figure 3, centre), in which two of the sulfur atoms lie adjacent to the BH group and one is rotated away, is marginally lower in energy (2.90 kcal mol −1 ) than the ion where all three sulfur atoms lie adjacent to the BH group (the 3:0 form; Figure 3, left). However, to date, five crystallographic reports on the uncoordinated Tm Me anion, show the 3:0 form 5–9. It is therefore likely that the form isolated in the solid state is stabilized by additional intermolecular forces.…”

“…Thus, the sodium cation was reintroduced to the model and methyl iodide was added as the cation source in the calculations. From experimental observations, the sodium cation can be expected to complex to the Tm Me anion in either the κ 3 ‐ S , S , S form or the κ 3 ‐ S , S , H form9–13 [A further complexation mode is known, κ 4 ‐ H , S , S , S , which can also be modelled and is of lower in energy (−2177.333629 a.u.) than the other models discussed 12.…”

Benzannulated tris(2-mercapto-1-imidazolyl)hydroborato ligands: tetradentate κ4-S3H binding and access to monomeric monovalent thallium in an [S3] coordination environment

“…Although there are relatively few structurally characterized [Tm R ]M alkali metal derivatives, 1b,8,13,14 it is evident that there exists a variety of structural types, which are influenced by the composition of the crystal. For example, (i) the aqua complex [Tm Me ]Na•4.5H 2 O is composed of discrete [Tm Me ] − anions ( i.e.…”

“…For example, (i) the aqua complex [Tm Me ]Na•4.5H 2 O is composed of discrete [Tm Me ] − anions ( i.e. κ 0 ) that exhibit a 3:0 conformation, 1b (ii) the DMF adduct, {[Tm Me ]Na(μ–DMF)} 2 , is dinuclear, featuring a [Tm Me ] ligand that binds in a κ 3 – S 2 H manner with a 3:0 conformation, 13 and (iii) the mixed solvate of composition [Tm Me ]Na•3.25H 2 O•0.5DMF possesses an uncoordinated [Tm Me ] − anion and a κ 1 -coordinated ligand, both of which adopt a 3:0 conformation. 13 …”