Two complexes with a zwitterionic dicarboxylate ligand,Mn（L）2（H2O）4 1 and Co（L）2（H2O）4 2（L = 1-carboxymethylpyridinium-4-carboxylate）,were synthesized and structurally characterized.Complex 1 crystallizes in monoclinic,space group P21 with a = 6.490（2）,b = 19.210（7）,c = 7.813（3） ,β = 92.716（5）o,V = 972.9（6） 3,Z = 2,Mr = 487.28,Dc = 1.663 g/cm3,F（000） = 502,μ = 0.749 mm-1,S = 1.060,the final R = 0.0377 and wR = 0.0893 for 3292 observed reflections with I 2σ（I）.Complex 2 is isomorphous with 1,with a = 6.478（2）,b = 19.052（7）,c = 7.742（3） ,β = 92.690（4）o,V = 954.6（6） 3,Z = 2,Mr = 491.28,Dc = 1.709 g/cm3,F（000） = 506,μ = 0.971 mm-1,S = 1.035,the final R = 0.0425 and wR = 0.0809 for 3289 observed reflections with I 2σ（I）.In the compounds,the mononuclear [M（L）2（H2O）4] units with trans-octahedral coordination geometry are linked into 3D architectures via hydrogen bonding（or second-sphere coordination） involving carboxylate groups and coordinated water molecules.The 3D networks illustrate a 3,8-connected net with Schlfli symbol（4·62）2（42·623·83）.
Using the ligand 4-sulfonyl-2,6-naphthalenedicarboxylate (SNDC),a coordination compound [Co(H2O)6]2 [Co(SNDC)2(H2O)4]·4H2O (1) was synthesized and characterized by elemental analysis,thermal analysis,IR and single crystal X-ray diffraction structure analysis. The complex crystallizes in the triclinic P1 space group. The crystallographic data are:a=0.722 4(3) nm,b=1.181 2(4)nm,c=1.353 4(5)nm,V=1.039 47(7)nm3,Z=1,Dc=1.795g·cm-3,R1=0.0558,wR2=0.148 7. In the complex,the cobalt(Ⅱ) mononuclear anion ([Co(SNDC)2(H2O)4]4-) adopts the six-coordinated octahedral geometry furnished by two carboxylate oxygen atoms from the SNDC ligands and four water oxygen atoms. The cobalt(Ⅱ) mononuclear anions are self-assembled into two-dimensional sheets through hydrogen bonding between coordinated water molecules and carboxylate oxygens and π-π stacking of the aromatic naphthalene moieties. The [Co(H2O)6]2+ cations are intercalated between the layers through additional hydrogen bonds involving coordinated water molecules and sulfonate/carboxylate oxygen atoms.
