Hydrothermal synthesis and structure of a new helical chain constructed from only molybdenum-oxide building blocks

The compound [NH3(CH2)(2)NH2(CH2)(2)NH3](2)[MO9O30] was synthesized at 170 degreesC via hydrothermal techniques from the starting materials of Na2MoO4.H2O, NH2(CH2)(2)NH(CH3)(2)NH2, and H2O. The compound crystallizes in the space group C2/c of the monoclinic system with a = 21.308(4) Angstrom, b = 9.234(2) Angstrom, c = 19.195(4) Angstrom, beta = 120.27(3)degrees, V = 3261.9(11)Angstrom(3), Z = 4. Two novel and symmetrically related helices coexist in the centrosymmetric solid, in which the two kinds of helices appear in the left-handed and right-handed enantiomorphs, respectively. This is the first example of a helical chain structure consisting of only molybdenum-oxide building blocks. The central axis about each helical chain is a 2-fold screw axis.