Structural Diversity in Zinc Phosphates and Phosphinates: Observation of a Lattice Water Dimer Sandwiched Between Phosphoryl Oxygen Atoms

Abstract

AbstractReactions of zinc acetate dihydrate with organic phosphates [(RO)2P(O)(OH)] (R = tBu, Ph) and phosphinic acids [PhR′P(O)(OH)] (R′ = Ph, H) have been investigated in the presence of 1,10‐phenanthroline (phen). While the use of di‐tert‐butyl phosphate (dtbp‐H) results in the formation of [Zn(phen)2(dtbp)(OH2)][dtbp](MeOH)(MeCOOH)(H2O)3 (1), the change of phosphorus source to diphenylphosphate (dpp‐H) yields an interesting phosphate‐bridged dinuclear complex [{Zn(phen)(dpp)}2{μ2‐dpp}2] (2). Mononuclear complexes [Zn(phen)2(dppi)2](H2O)2 (3) and [Zn(phen)2(ppi)2](H2O) (4) have been obtained from similar reactions by the use of diphenylphosphinic acid (dppi‐H) and phenylphosphinic acid (ppi‐H), respectively. The high steric bulk of the dtbp ligand results in the formation of the cationic complex 1, where only one of the dtbp ligands is directly coordinated to the metal atom, leaving the second dtbp molecule as the counter anion. The inorganic core of dinuclear zinc phosphate 2 resembles the single four‐ring (S4R) secondary building unit of framework zinc phosphates. Compounds 3 and 4 are neutral monomeric hexacoordinate complexes with two chelating 1,10‐phen ligands and two monodentate phosphinate ligands. The two lattice water molecules in 3 form an interesting water dimer (H2O)2. These water dimers link the mononuclear zinc complexes in the lattice to form an H‐bonded one‐dimensional polymer. Similarly, the lattice water present in 4 serves to link the zinc phenylphosphinate molecules through hydrogen bonding in the form of a 1‐D polymer. The reaction of the precursor complex [Zn(bpy)2(OAc)](ClO4)·H2O with dpp‐H, dppi‐H, and ppi‐H in methanol leads to the formation of zinc phosphate [Zn(bpy)2(dpp)]2(ClO4)2·H2O (5) and phosphinates [Zn(bpy)2(dppi)]2(ClO4)2 (6) and [Zn(bpy)2(ppi)]2(ClO4)2 (7), respectively. The molecular structures of 1–5 and 7 have been determined by single‐crystal X‐ray diffraction studies. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)