TIN(II) OXALATES SYNTHESIZED IN THE PRESENCE OF STRUCTURE-DIRECTING ORGANIC AMINES - MEMBERS OF A POTENTIALLY VAST CLASS OF NEW OPEN-FRAMEWORK AND RELATED MATERIALS

Three new tin(II) oxalate materials, of which one has an open-framewor k layered structure, have been synthesized hydrothermally in the prese nce of structure-directing organic amines. Crystal data: oxalate 1, 3) (2)NH(CH2)(4)NH(CH3)(2)](2+)[Sn-2(C2O4)(3)](2-), monoclinic, space gro up P2(1)/c (No. 14) a = 8.427(2) Angstrom, b = 14.257(1) Angstrom, c = 8.868(2) Angstrom, beta = 100.3(1)degrees, V = 1048.3(2) Angstrom(3), Z = 4, M = 738.6(1), D-calc = 2.06(1) g cm(-3), Mo K alpha, R-F = 0.0 5; oxalate II, [C(NH2)(3)](2)(+)-[Sn-2(C2O4)(3)](2-). 2H(2)O, triclini c, space group P (1) over bar (No. 2), a = 7.564(1) Angstrom, b = 10.6 33(1) Angstrom, c = 12.050(1) A, alpha = 87.9(1)degrees, beta = 85.2(1 )degrees, gamma = 85.9(1)degrees, V = 962.8(1) Angstrom(3), Z = 2, M = 699.6(1), D-calc = 2.25(1)g cm-3, Mo K alpha, R-F = 0.06; oxalate III , [C5N2H16](2+)[Sn-2(C2O4)(3)](2-) orthorhombic, space group Pmmn (No. 59), a = 8.281(2) Angstrom, b = 17.828(4) Angstrom, c = 4.585(1) Angs trom, V = 678.4(2) Angstrom(3), Z = 4, M = 605.4(1), D-calc = 2.37(1) g cm(-3), Mo K alpha, R-F = 0.03. In I, the Sn atoms are hexacoordinat ed with oxygen and form porous tin oxalate sheets with the protonated diamine sitting in the middle of the pore, while, in II, four-coordina ted Sn atoms form tin oxalate monomer units which are held together by the protonated guanidium cations. In III, we again see the presence o f the anionic tin oxalate monomer units hydrogen bonded to the protona ted 1,5-diaminopentane cations giving rise to one-dimensional ribbons. These amine-containing oxalate materials constitute a new family of s tructures where hydrogen bonding interactions, involving the amines, p lay an important role. The observation of six-coordination for tin in I which forms a pseudo pentagonal bipyramid akin to that in a 14 elect ron system in noteworthy. The novel features of oxalate I-III suggest that exploration of various metal dicarboxylates prepared in the prese nce of structure-directing agents may indeed yield new types of intere sting structures with unusual coordination.