A new series of 3,5-diamino-1,2,4-triazolium(1+) inorganic salts and their potential in crystal engineering of novel NLO materialsElectronic supplementary information (ESI) available: experimental powder data for dat2SeO42H2O, dat2SO42H2O, datClO4, datNO3, dat2Cl2H2O, datH2PO3 and datH2PO4; selected bond lengths [A°] and angles [°] for dat2SeO42H2O, dat2SO42H2O, datClO4, datNO3, dat2Cl2H2O, datH2PO3 and datH2PO4; comparison of geometric parameters; Calculated (scaled) fundamental frequencies (cm

Seven inorganic salts of 3,5-diamino-1,2,4-triazole (dat) with inorganic acids were prepared within our project focused on the crystal engineering of novel NLO materials and their X-ray structures were determined. Three triclinic compounds, dat(1+) selenate dihydrate, dat(1+) sulphate dihydrate and dat(1+) perchlorate, crystallize in the space group P 1&cmb.macr;. Three monoclinic structures of dat(1+) - i.e. nitrate, chloride hemihydrate and hydrogen phosphite crystallize in P 2 1 / c , P 2 1 / n and P 2 1 / c , respectively. Finally, the most promising structure of dat(1+) dihydrogen phosphate is orthorhombic (the space group Fdd 2). The structure is formed by anionic layers parallel to the ac plane and the cationic chains parallel to the c axis. The FTIR and Raman spectra of the title compounds have been recorded and discussed. The assignment of the spectra is based on a quantum-chemical calculation and the factor group analysis. Quantitative powder measurements of the second harmonic generation of the only non-centrosymmetric dat(1+) dihydrogen phosphate at 1064 nm were performed and a relative efficiency equal to KDP ( i.e. potassium dihydrogen phosphate) was observed. The consequent study of single crystal samples enabled the estimation of NLO tensor coefficients of this material. The preparation and characterization of seven inorganic salts of guanazole are presented. The efficiency of SHG and the values of NLO tensor coefficients were estimated for the most promising novel material - guanazolium(1+) dihydrogen phosphate.