Hydrothermal reaction of benzene-1,2,4,5-tetracarboxylic(Btec) dianhydride with La2O3 lead to a new organometallic compound, [La2(betc)(Hbtec)(H2O)3][HCONH(CH3)2](I). Single-crystal X-ray diffraction analysis reveals that it crystallizes in monoclinic space group P21/n that mimics orthorhombic space group Pnma(viz. pseudo-merohedral twinning structure) with a = 7.6002(16), b = 18.954(4), c = 18.213(4) ?, β = 90.121(3)o, V = 2623.5(9) ?3, Z = 4, Mr = 907.21, Dc = 2.297 g/cm3, F(000) = 1752, μ(Mo Kα) = 3.32 mm-1, R = 0.0575 and w R = 0.0956. The structure of I features a 3-D framework constructed by La(III) cations, btec4- ligands, Hbtec3-ligands and coordinated water molecule. All of the La(III) cations are 10-coordinated by O atoms into 1-D infinite chains, which are further interconnected by C atoms of btec ligands to form a 3-D framework.
