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

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{HN=C(NC5H10)N(Ph)C(NH2)=NPh}(2)](Cl)(2), [1](Hal)(2) (Hal = Cl, Br, I), and [Pt{HN=C(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(-)center dot center dot center dot 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.