Synthesis and structural characterization of a tetra-cobalt(II)-substituted sandwich-type tungstophosphate, (1,3-H2dap)2H4[Co4(1,3-Hdap)2(α-BPW9O34) 2].3H2O

摘要

A sandwich-type tungstophosphate, (1,3-H _2dap) _2H _4[Co _4 (1,3-Hdap) _2(a-B-PW _9O _(34)) _2]. 3H _2O (1,3-dap=1,3-diaminopropane), was hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction, elemental and thermo-gravimetric analysis, and IR and UV spectroscopy. The compound presents a classical tetra-transition metal-substituted sandwich framework, [Co _4(1,3-Hdap) _2(a-B-PW _9O _(34)) _2] ~(8-), which contains two lacunary a-B-[PW _9O _(34)] ~(9-) Keggin units linked by a rhomblike Co _4O _(14)(1,3-dap) _2 cluster lying across an inversion center. The Co ~(2+) ions are coordinated by a mono-protonated dap ligand. Isolatedly protonated 1,3-dap units act as counter-ions interacting with the [PW _9O _(34)] ~(9-) polyanions via hydrogen bonds forming a three-dimensional framework.