The complexing properties of the phenylsquarate ligand with Ru(II), Pt(II), Gd(III) and Tb(III) ions

摘要

Reaction of 3-phenyl-4-hydroxycyclobut-3-ene-l ,2-dione (phenylsquarate) with Ru( dmso )_4C1_2 in 'acetonitrile afforded crystals of the monomeric species Ru(dmso)3CI(H_2O)(C_6H_5C_4O_3).H_2O (I) in which the ruthenium is in a slightly distorted octahedral geometry with three fac S-bonded dm so ligands. No complexation occurs when Pt(NH_3)_4Cl_2 is reacted with the same ligand in aqueous solution; instead, the hydrogen-bonded salt [Pt(NH)_4][C_6H_5C_4O_3]_2.H_2O (2) is produced. The isomorphous complexes {[M(Il-C_6H_5C_4O_3)(C_6H_5C_4O_3)_2(H_2O)4]. H_2O} n [M = Tb (3), Gd (4)] formed by the reaction of the phenylsquarat.e ligand with the respective metal nitrate contain eight-coordinate metal centres surrounded by two ll-l,3-bridged and two pendant phenylsquarate ligands and four aqua ligands. In the solid state, 3 and 4 form interleaved 7t-stacked and hydrogen-bonded sheets with pronounced hydrophobic and hydrophilic surfaces. In compounds 1-4, the phenylsquarate ligands participate in 7t-7t interactions and exhibit multiple bond localisation, the pattern of bonding being .the same in each structure.