Hydrothermal Synthesis and Structure of a New Helical Chain Constructed from Only Molybdenum−Oxide Building Blocks

The compound [NH3(CH2)2NH2(CH2)2NH3]2[Mo9O30] was synthesized at 170 °C via hydrothermal techniques from the starting materials of Na2MoO4·H2O, NH2(CH2)2NH(CH3)2NH2, and H2O. The compound crystallizes in the space group C2/c of the monoclinic system with a = 21.308(4) Å, b = 9.234(2) Å, c = 19.195(4) Å, β = 120.27(3)°, V = 3261.9(11)Å3, 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.