Molecular Indium(III) Phosphonates Possessing Ring and Cage Structures. Synthesis and Structural Characterization of [In₂(<i>t</i>‑BuPO₃H)₄(phen)₂Cl₂] and [In₃(C₅H₉PO₃)₂(C₅H₉PO₃H)₄(phen)₃]·NO₃·3.5H₂O

Two novel indium­(III) phosphonates, [In2(t-BuPO3H)4(phen)2Cl2] (1) and [In3(C5H9PO3)2(C5H9PO3H)4(phen)3]·NO3·3.5H2O (2) with phen = 1,10-phenanthroline, have been synthesized by solvothermal reactions involving indium­(III) salts and organophosphonic acids. 1 is a dinuclear compound where the two indium centers are bridged by a pair of isobidentate phosphonate ligands, [t-BuP­(O)2OH]−, resulting in an eight-membered (In2P2O4) puckered ring. Compound 2 is trinuclear; the In3 platform is held together by two bicapping tripodal phosphonate ligands from the top and bottom of the indium plane. In addition, two bridging monoanionic phosphonate ligands serve to bind two pairs of indium centers. Both 1 and 2 also contain monodentate monoanionic phosphonate ligands. The solid-state MAS 31P NMR spectrum of complex 1 shows two signals at 21.9 and 29.3 ppm. Compound 2 contains signal maxima at 25.8 and 28.9 ppm, with a shoulder at 31.5 ppm. Room temperature solid-state fluorescence spectra of 1 and 2 are characterized by strong emission bands at 385 nm (λex = 350 nm) and 395 nm (λex = 350 nm), respectively, which are red-shifted with respect to the emission of free phenanthroline.本研究采用铟(III)盐与有机膦酸作为反应物，通过溶剂热反应成功合成了两种新型铟(III)膦酸盐配合物：[In₂(t-BuPO₃H)₄(phen)₂Cl₂]（化合物1）与[In₃(C₅H₉PO₃)₂(C₅H₉PO₃H)₄(phen)₃]·NO₃·3.5H₂O（化合物2），其中phen为1,10-邻菲啰啉（1,10-phenanthroline）。化合物1为双核配合物，两个铟中心由一对双齿桥联膦酸配体[t-BuP(O)₂OH]⁻连接，形成八元(In₂P₂O₄)褶皱环。化合物2为三核配合物，其In₃平面结构由两个分别位于铟平面上下的三齿盖帽膦酸配体固定；此外，两个桥连单阴离子膦酸配体用于连接两对铟中心。化合物1与2均含有单齿单阴离子膦酸配体。配合物1的固态魔角旋转³¹P核磁共振（MAS ³¹P NMR）谱在21.9 ppm与29.3 ppm处出现两个信号峰；化合物2的谱图在25.8 ppm与28.9 ppm处存在信号主峰，并在31.5 ppm处带有一个肩峰。室温条件下，化合物1与2的固态荧光光谱分别在385 nm（激发波长λ_ex=350 nm）与395 nm（激发波长λ_ex=350 nm）处呈现强发射带，其发射波长相较于游离的1,10-邻菲啰啉发生了红移。