Alkali metal halogenides coordination compounds with hexamethylenetetramine

Six coordination compounds: [Li(H2O)4]+·hmta·Cl−, [Li(H2O)4]+·hmta·I−, [Na(H2O)4(hmta)]22+·2H2O·2Br−, [Na(H2O)4(hmta)]22+·2H2O·2I−, [K(H2O)(hmta)I]n and [Rb(H2O)(hmta)I]n, have been synthesized and characterised by IR spectroscopy, thermogravimetry coupled with differential thermal analysis, elemental analysis and X-ray crystallography. Both the sodium compounds are isostructural in a solid state, an isostructurality is also observed between compounds containing potassium and rubidium iodides. The sodium compounds exist as dimers (dinuclear core of the complex ion is created by two sodium cations and two water molecules). The molecules of potassium and rubidium compounds are assembled to the two dimensional hybrid nets. The each potentially multifunctional ligand (the hmta) exists in the outer coordination sphere in lithium compounds, acts in a monodentate mode in sodium compounds and in bidentate-bridging modes in potassium and rubidium compounds. The lithium ions are four coordinated, and the sodium, potassium and rubidium ions are six coordinated. Thermal analyses show that the investigated compounds decompose gradually with the formation of alkali metal halides which, during the further heating, are totally removed or they undergo partial decomposition to oxides.