SYNTHESES AND CHARACTERIZATION OF SALTS OF N,N',N''-TRICYANOGUANIDINATE DIANION (C4N62-) AND THE OBSERVATION OF A STRONG NONLINEAR-OPTICAL EFFECT BY 2ND-HARMONIC GENERATION FROM NA2C4N6-CENTER-DOT-H2O

Reaction of cyanamide with dimethyl cyaniminodithiocarbonate in the pr esence of potassium carbonate gives the potassium salt of N,N '-dicyan o-1,3-diaza-2-thiomethoxypropenide (KC4H3N6S) Synthesis of disodium N, N ',N ''-tricyanoguanidinate (Na2C4N6 . H2O) was accomplished by the r eaction of disodium cyanamide with dimethyl cyaniminodithiocarbonate i n N,N-dimethylacetamide at 120-140 degrees C. This salt exhibits a ver y strong nonlinear optical effect as assayed by second harmonic genera tion. The monoguanidinium monosodium salt of N,N ',N ''-tricyanoguanid inate was synthesized by partial cation ion exchange of the disodium s alt. The crystal structure of this salt, Na[C(NH2)(3)][C(NCN)(3)], was solved in the space group P (3) over bar with Z = 2, alpha = 8.942(2) Angstrom, b = 8.942(2) Angstrom, c = 6.576(4) Angstrom, alpha = 90.00 , beta = 90.00, gamma = 120.00, and V = 455.4(4) Angstrom(3).