On the sequence of three related phases of [Ni(H2O)2(15-crown-5)](HSO4)2 in the temperature range 110-295 K

Attempts to prepare the compound [Ni(H2O)2(15-crown-5)](X)2 were eventually successful with X = NO_3^- provided that a synthetic route aimed at restricting water was followed. Application of this method was extended to make the analogous compound with X = HSO_4^-, for which three symmetry-related phases were isolated between 295 and 110 K: a room-temperature phase with Z' = ½ [phase (I)], an intermediate-temperature phase with Z' = 1 [phase (II)] and a low-temperature phase with Z' = 2 [phase (III)]. The phases are related by two reversible solid-solid phase transitions, and both transitions take place without a significant loss of crystallinity. In the phase sequence (I) [left right arrow] (II) [left right arrow] (III) (Z': ½ [left right arrow] 1 [left right arrow] 2), the crystal packing remains remarkably similar but the degree of order in the crystal changes significantly; the structure is very disordered at room and intermediate temperatures but is ordered at 110 K. The compound [Ni(H2O)2(15-crown-5)](HSO4)2 has a complicated hydrogen-bonding network, which contains O-H...O bonds between the counterions. Structural changes are largest along some face-diagonal directions in the sequence (I) [left right arrow] (II) [left right arrow] (III)

Ni(salen): a system that forms many solvates with interacting Ni atoms

Recrystallization of [N,N’-Ethylene-bis(salicylideneiminato)]-nickel(II) [Ni(salen)] has been carried out from a large selection of solvents. Crystals can be either solvent free or solvates. This study is based on X-ray crystal structure determinations, which include the redetermination of Ni(salen) at low-temperature, the finding of three new solvates of Ni(salen), that is, Ni(salen)·CH2Cl2, Ni(salen)·AcOH, and Ni(salen)·1.5MeOH, and the reexamination of the known solvate Ni(salen)·chloroform at low- and room-temperature. The crystal structures of Ni(salen) and its solvates are stabilized by salen···salen and/or solvent···salen and/or solvent···solvent intermolecular interactions. A special case is the crystal structure of Ni(salen)·1.5MeOH where the salen/solvent ratio is 2:3 rather than 1:1. For all solvated structures, the solvent and Ni(salen) molecules always interact via Dsolvent−H···Osalen (Dsolvent = C, O) hydrogen bond interactions, the strengths of which depend on the solvent of recrystallization. All structures are characterized by weak Ni−Ni interactions, which are found either in centrosymmetric dimeric units or along one-dimensional chains. Such interactions are favored because of the d8 electronic configuration of Ni(II) and the pseudoplanar geometry of Ni(salen)

CuI Thiolate Reactivity with Dioxygen: The Formation of CuII Sulfinate and CuII Sulfonate Species via a CuII Thiolate Intermediate

CuI(Py2NS) (1) is formed by addition of CuI to a solution of the pyridyl-thiol ligand N-(2-mercaptopropyl)- N,N-bis(2-pyridylmethyl)amine (Py2NSH). Oxidation of complex 1 by air leads to the formation of CuII sulfinate and CuII sulfonate complexes, providing a model for the oxidative degeneration of copper−sulfur enzymes. Crystal structures were obtained for two CuI I sulfinate complexes, [CuI I 2(Py2NSO2 ) 2](BF4 ) 2 ·2(CH3 ) 2CO (4a) and [CuII 2(Py2NSO2)2(OTf)2] (4b), which were further characterized by UV−vis and EPR spectroscopy and cyclic voltammetry. Furthermore, two CuII sulfonate complexes with the proposed formulas CuII 2(Py2NSO3)2(BF4)2 (5a) and CuII 2(Py2NSO3)2(OTf)2 (5b) have been isolated and characterized. Monitoring the oxidation of 1 by UV−vis indicates that the oxidation proceeds via a dinuclear CuII μ-thiolate complex (3); as an intermediate an octanuclear mixed-valent CuI 4CuII 4 cluster with formula [CuI 4CuII 4(Py2NS)4(μ-OH)2(CH3CN)6](ClO4)6·2CH3CN (2) was isolated and characterized by X-ray single crystal structure determination

A molecular cage of nickel(II) and copper(I): a [{Ni(L)2}2(CuI)6] cluster resembling the active site of nickel-containing enzymes

A new mononuclear low-spin nickel(II) dithiolato complex, [NiL2] (1), reacts with copper iodide to form the heterooctanuclear cluster [{Ni(L)2}2(CuI)6] (2) with four trigonal-planar CuI2S and two tetrahedral CuI2S2 sites; anagostic interactions between the nickel(II) ions and aromatic protons have been demonstrated by variable-temperature NMR studies to pertain in solution

SIAPhos: Phosphorylated Sulfonimidamides and their Use in Iridium-Catalyzed Asymmetric Hydrogenations of Sterically Hindered Cyclic Enamides

Phosphorylated sulfonimidamides (SIAPhos) undergo ion exchange reactions with cationic complexes, [Rh(cod)2BF4] and [Ir(cod)2BarF], or neutral complexes [Rh(cod)Cl]2 and [Ir(cod)Cl]2, leading to unprecedented neutral complexes with P-N-S-N chelates. Use of the resulting neutral iridium complexes in asymmetric hydrogenation reactions of tri- and tetrasubstituted enamides leads to products with high enantioselectivities (up to 92% ee)

Supramolecular NHC ligands: on the influence of ZnII-templates on the activity of RhI(cod) complexes in carbene polymerization

New RhI(cod) complexes of N-heterocyclic carbene ligands containing a pending pyridyl moiety for subsequent binding of ZnII-templates were designed for supramolecular catalyst control in carbene polymerization reactions. ZnII-templates indeed have an influence on the yields and the polymer molecular weights (and weight distributions) produced by these supramolecular assemblies. However, control experiments reveal that the effect of the ZnII-template on the polymerization results is general and not due to the assembly formation

The intriguing substitution behavior of CO with bidentate phosphine ligands induced by a gem-dialkyl effect

The reaction of the complexes [FeCpX(CO)2] (X = Cl, Br, I) into either [FeCp(CO)(PP)]X or [FeCpX(PP)] (PP = a bidentate diphosphine ligand) is shown to be highly dependent of the phosphine ligand used. Diphosphine ligands that form stable chelates favor formation of the neutral complex, whereas diphosphine ligands that form less stable chelates favor formation of the cationic complex. Thus, with the use of dppdmp (= 1,3-bis(diphenylphosphino)-2,2-dimethylpropane) the [FeCpX(PP)] complexes (X = Cl, Br, I) are selectively formed, induced by a gem-dialkyl effect. Apart from the bidentate phosphine ligand, the halide ion present in the iron complex has a significant influence on the course of the substitution reaction

One-Pot Synthesis and Immobilisation of Sulfonate-Tethered N-Heterocyclic Carbene Complexes on Polycationic Dendrimers

Easy does it! Anion-tethered N-heterocyclic carbene metal complexes (metal=AuI, RhI) were efficiently synthesised and immobilised on a polycationic dendrimer by an in situ transmetallation-immobilisation reaction, leading to discrete non-covalent metallodendritic assemblie