Synthesis and Crystal Structure of （C6NaH18）2Ti4O4（C204）7.4H2O

The title compound (C6N3H18)2Ti4O4(C204)7.4H2O 1 (C13H22N3O18Ti2, Mr=604.14) was synthesized by the reaction of Ti(SO4)2, H2C2O4.2H2O and N-(2-ammonioethyl)-piperazinium (AEPP) in aqueous solution. The single-crystal X-ray analysis has revealed that 1 crystallizes in the triclinic system, space group P-↑1 with a=9.1437(6), b=11.4991(10), c=11.6975(8)A, α=96.2915(18), β=107.998(3), γ=104.276(4)°,V=1110.35(14)A^3, Z=2, Dc=1.807 g/cm^3, F(000) =618,μ= 0.815mm^-1, the final R=0.0463 and wR = 0.1264 for 3718 observed reflections with 1 >2γ(I). X-ray crystal-structure analysis suggests that compound 1 consists of [Ti4O4(C2O4)7]^6- anion and two protonated N-(2-ammonioethyl)piperazinium cations. The anions are linked into an infinite chain through Ti4O4(C2O4)8 by sharing the oxalates as bridging ligands.