Lasagna-type arrays with halide–nitromethane cluster filling. The first recognition of the Hal−⋯HCH2NO2 (Hal = Cl, Br, I) hydrogen bonding

Abstract

The previously predicted ability of the methyl group of nitromethane to form hydrogen bonding with halides is now confirmed experimentally based on X-ray data of novel nitromethane solvates followed by theoretical ab initio calculations at the MP2 level of theory. The cationic (1,3,5-triazapentadiene)Pt^II complexes [Pt{HNC(NC₅H₁₀)N(Ph)C(NH₂)NPh}₂](Cl)₂, [1](Hal)₂ (Hal = Cl, Br, I), and [Pt{HNC(NC₄H₈O)N(Ph)C(NH₂)NPh}₂](Cl)₂, [2](Cl)₂, were crystallized from MeNO₂-containing systems providing nitromethane solvates studied by X-ray diffraction. In the crystal structure of [1][(Hal)₂(MeNO₂)₂] (Hal = Cl, Br, I) and [2][(Cl)₂(MeNO₂)₂], the solvated MeNO₂ molecules occupy vacant spaces between lasagna-type layers and connect to the Hal⁻ ion through a weak hydrogen bridge via the H atom of the methyl thus forming, by means of the Hal⁻⋯HCH₂NO₂ contact, the halide–nitromethane cluster “filling”. The quantum-chemical calculations demonstrated that the short distance between the Hal⁻ anion and the hydrogen atom of nitromethane in clusters [1][(Hal)₂(MeNO₂)₂] and [2][(Cl)₂(MeNO₂)₂] is not just a consequence of the packing effect but a result of the moderately strong hydrogen bonding.