Pyridineboronic Acids as Useful Building Blocks in Combination with Perchloroplatinate(II) and -(IV) Salts: 1D, 2D, and 3D Hydrogen-Bonded Networks Containing X-H···Cl₂Pt⁻ (X = C, N⁺), B(OH)₂···Cl₂Pt⁻, and B(OH)₂···(HO)₂B Synthons

Abstract

Five metal complexes have been prepared by reacting 3- and 4-pyridineboronic acid (3- and 4-pba) with potassium tetrachloroplatinate (K2PtCl4) and hexachloroplatinic(IV) acid hydrate (H2PtCl6·aq): [4-pbaH]2[PtCl4], [3-pbaH]2[PtCl4], [4-pbaH][Pt(4-pba)Cl3], cis-[Pt(4-pba)2Cl2]·H2O, and cis-[PtIV(3-pba)2Cl4]·2H2O. All compounds have been characterized by single-crystal X-ray diffraction analysis, showing that the primary hydrogen bonding interactions of the resulting 1D, 2D, and 3D networks contain at least one of the following synthons: X-H···Cl2Pt− (X = C, N+), B(OH)2···Cl2Pt−, and B(OH)2···(HO)2B. The dimensions are enhanced further by secondary +N−H···ClPt, O−H···O, and O−H···ClPt hydrogen bonding interactions between donor and acceptor atoms located at the periphery of these synthons. Additional weak C−H···O, C−H···Cl, B···N, and π···π stacking interactions stabilize the crystal structures further.