Anna V. Pavlishchuk

Structural trends in a series of isostructural lanthanide–copper metallacrown sulfates (LnIII = Pr, Nd, Sm, Eu, Gd, Dy and Ho): hexaaquapentakis[μ3‐glycinehydroxamato(2−)]sulfatopentacopper(II)lanthanide(III) heptaaquapentakis[μ3‐glycinehydroxamato(2−)]sulfatopentacopper(II)lanthanide(III) sulfate hexahydrate

The seven isostructural complexes, [Cu(5)Ln(C(2)H(4)N(2)O(2))(5)(SO(4))(H(2)O)(6.5)](2)(SO(4))·6H(2)O, where Ln(III) = Pr, Nd, Sm, Eu, Gd, Dy and Ho, are representatives of the 15-metallacrown-5 family. Each dianion of glycinehydroxamic acid (GlyHA) links two Cu(II) cations forming a cyclic [CuGlyHA](5) frame. The Ln(III) cations are located at the centre of the [CuGlyHA](5) rings and are bound by the five hydroxamate O atoms in the equatorial plane. Five water molecules are coordinated to Cu(II) cations, and one further water molecule, located close to an inversion centre between two adjacent [Cu(5)Ln(GlyHA)(5)](2+) cations, is disordered around this inversion centre and coordinated to a Cu(II) cation of either the first or second metallacrown ether. Another water molecule and one of the two crystallographically independent sulfate anions are coordinated, the latter in a bidentate fashion, to the Ln(III) cation in the axial positions. The second sulfate anion is not coordinated to the cation, but is located in an interstitial position on a crystallographic inversion centre, thus leading to disorder of the O atoms around the centre of inversion. The Ln-O bond distances follow the trend of the lanthanide contraction. The apical Ln-O bond distances are very close to the sums of the ionic radii. However, the Ln-O distances within the metallacrown units are slightly compressed and the Ln(III) cations protrude significantly from the plane of the otherwise flat metallacrown ligand, thus indicating that the cavity is somewhat too small to accommodate the Ln(III) ions comfortably. This effect decreases with the size of the lanthanide cation from complex (I) (Ln(III) = Pr; 0.459) to complex (VII) (Ln(III) = Ho; 0.422), which indicates that the smaller lanthanide cations fit the cavity of the pentacopper metallacrown ring better than the larger ones. The diminished contraction of Ln-O distances within the metallacrown planes leads to an aniostropic contraction of the unit-cell parameters, with a, c and V following the trend of the lanthanide contraction. The b axes, which are mostly aligned with the rigid planes of the metallacrown units, show only a little variation between the seven compounds.

Tetra­kis[bis­(pyridin-2-yl)amine-κN2](nitrato-κO)silver(I)

In the title complex, [Ag(NO3)(C10H9N3)4], the nitrate ligand is found to be disordered over two sets of positions, with occupancy factors of 0.473 (5) and 0.527 (5). The AgI ion is located in a square-pyramidal coordination environment formed by four N atoms from four bis(pyridin-2-yl)amine ligands and one O atom from a nitrate ligand. Weak interactions between the AgI ions and the nitrate anions acting in a monodentate mode [Ag⋯O = 2.791 (13) and 2.816 (9) Å for the major component of the nitrate ligand, and 2.865 (8) and 2.837 (8) Å for the minor component] link the complex molecules into a chain along [001]. N—H⋯O hydrogen bonds are observed.

Tetra­butyl­ammonium 2-[2,5-dimethyl-3-(4-nitro­phen­yl)-2,3-dihydro-1,2,4-oxadiazo­lium-4-yl]nona­hydro-closo-deca­borate

The title ionic compound, C16H36N+·C10H20B10N3O3 −, consists of a tetrabutylammonium cation and a closo-decaborate cluster anion, which is bound to the substituted 2,3-dihydro-1,2,4-oxadiazole ring through a B—N bond [1.540 (2) Å]. The distances between connected B atoms in the decaborate cluster range from 1.689 (2) to 1.844 (2) Å. The 2,3-dihydro-1,2,4-oxadiazole ring adopts an envelope conformation with the N atom as the flap atom.

Bis-{(E)-3-[2-(hy-droxy-imino)-propan-amido]-2,2-dimethyl-propan-1-aminium} bis[μ-(E)-N-(3-amino-2,2-dimethyl-prop-yl)-2-(hy-droxy-imino)-propanamido-(2-)]bis-{[(E)-N-(3-amino-2,2-dimethyl-prop-yl)-2-(hy-droxy-imino)-propanamide]-copper(II)} bis-((E)-{3-[2-(hy-droxy-imino)-propanamido]-2,2-dimethyl-prop-yl}carbamate) acetonitrile disolvate.

The reaction between copper(II) nitrate and (E)-N-(3-amino-2,2-dimethylpropyl)-2-(hydroxyimino)propanamide led to the formation of the dinuclear centrosymmetric copper(II) title complex, (C8H18N3O2)2[Cu2(C8H15N3O2)2(C8H17N3O2)2](C9H16N3O4)2·2CH3CN, in which an inversion center is located at the midpoint of the Cu2 unit in the center of the neutral [Cu2(C8H15N3O2)2(C8H17N3O2)2] complex fragment. The Cu2+ ions are connected by two N—O bridging groups [Cu⋯Cu separation = 4.0608 (5) Å] while the CuII ions are five-coordinated in a square-pyramidal N4O coordination environment. The complex molecule co-crystallizes with two molecules of acetonitrile, two molecules of the protonated ligand (E)-3-[2-(hydroxyimino)propanamido]-2,2-dimethylpropan-1-aminium and two negatively charged (E)-{3-[2-(hydroxyimino)propanamido]-2,2-dimethylpropyl}carbamate anions, which were probably formed as a result of condensation between (E)-N-(3-amino-2,2-dimethylpropyl)-2-(hydroxyimino)propanamide and hydrogencarbonate anions. In the crystal, the complex fragment [Cu2(C8H15N3O2)2(C8H17N3O2)2] and the ion pair C8H18N3O2 +.C9H16N3O4 − are connected via an extended system of hydrogen bonds.

Crystal structure of μ-oxalodi­hydroxamato-bis­[(2,2′-bipyrid­yl)(di­methyl sulfoxide-κO)copper(II)] bis­(perchlorate)

In this article we report a synthetic procedure and structure of the novel dinuclear copper(II) complex, with a bridging oxalodihydroxamate ligand and terminal 2,2′-bipyridine and DMSO ligands completing the square pyramidal coordination spheres of the Cu(II) centres..