Study of Acidic (Tetracaprolactam) Dodecamolybdosilicate of the Composition (C6H11NO)4.5Н4[SiМо12O40]

New caprolactam dodecamolybdosilicate of the composition (C6H11NO)4.5Н4[SiМо12O40] (I) is synthesized. Chemical and crystallographic analyses, NMR and IR spectroscopic studies are performed. Compound I is found to crystallize in the monoclinic system with the space group P21/n. Unit cell parameters are: a = 19.945(4) A, b = 13.340(3) A, c = 28.110(6) A, β = 110.75(3)°, ρcalc = 2.232 g/cm3, М = 2350.63, Z = 4, V = 6994(3) A3.