G. Attilio Ardizzoia

Oxidation reaction of [{Cu(Hpz)2Cl}2](Hpz = pyrazole): synthesis of the trinuclear copper(II) hydroxo complexes [Cu3(OH)(pz)3(Hpz)2Cl2]·solv (solv = H2O or tetrahydrofuran). Formation, magnetic properties, and X-ray crystal structure of [Cu3(OH)(pz)3(py)2Cl2]·py (py = pyridine)

The trinuclear copper(II) complexes [Cu3(OH)(pz)3(Hpz)2Cl2]·solv (Hpz = pyrazole, pz = pyrazolate anion, solv = H2O or tetrahydrofuran) have been obtained by oxidation reactions of [{Cu(Hpz)2Cl}2]. When treated with pyridine(py), both CuII derivatives gave the related compound [Cu3(OH)(pz)3-(py)2Cl2]·py, which has been characterized by a single-crystal X-ray structure analysis. Crystals are orthorhombic, space group Pnma(no. 62), a= 19.883(3), b= 15.063(3), c= 9.495(2)A, Z= 4, R= 0.035 and R′= 0.041 for 1 472 absorption corrected reflections having I > 3σ(I).

UNIQUE FORMATION OF A CRYSTAL PHASE CONTAINING CYCLIC OLIGOMERS AND HELICAL POLYMERS OF THE SAME MONOMERIC FRAGMENT

The yellow, microcrystalline compound [Cu(pymo)] (Hpymo=2-hydroxypyrimidine) has been characterized with the newly emerging technique of ab initio X-ray powder diffraction. A unique and unprecedented crystal phase containing cyclic oligomers and infinite helical polymers (see picture) of the same monomeric fragment is selectively formed upon reaction of [Cu(CH3 CN)4 ][BF4 ] and Hpymo with NEt3 .

Alkyne oligomerization catalyzed by molybdenum(0) complexes

Abstract Three new molybdenum(0) complexes, [Mo(CO)3(Hpz)3] (1), [Mo(CO)2(Hpz)2(DMAD)2] (2), (DMAD=dimethyl acetylenedicarboxylate) and [Mo(CO)3(1-Me-imidazole)3] (3) were synthesized and characterized. Their activity and selectivity in alkyne cyclotrimerization and co-trimerization reactions was investigated. The molecular structures of 1 and 2 have been determined by unconventional powder and standard single-crystal diffraction methods, respectively. 1 consists of a pseudo-octahedral complex of C3 symmetry, with the ligands in fac disposition; complex 2, of idealized C2 symmetry, is obtained by substitution of one CO and one pyrazole in 1 by two DMAD ligands, and shows the rare trans configuration of π-bound acetylenic moieties.

Thermally robust metal coordination polymers: The cobalt, nickel, and zinc pyrimidin-2-olate derivatives

A number of coordination polymers of the pymo ligand (Hpymo = 2-hydroxypyrimidine) have been prepared and fully characterized by chemical, spectroscopic, and thermal analyses. Their complete crystal structures have been solved ab initio from laboratory X-ray powder diffraction data and ultimately refined by the Rietveld method. The M(pymo)2 species (M = Co, Ni, Zn) consist of structurally related threedimensional frameworks of very high thermal stability (decomposing under N2 only at T . 550 °C), with the metal atoms, linked by μ2-η-η (N;N9) (Co, Zn) or μ2-η-η (N,O;N9)

Oligomerization and polymerization of alkynes catalyzed by rhodium(I) pyrazolate complexes

Three new Rh(I) derivatives containing the dcmpz ligand (Hdcmpz: 3,5-dicarbomethoxypyrazole) have been prepared and employed as catalysts or catalyst precursors in the cyclotrimerization of terminal and internal alkynes and in the polymerization of ethyne to polyacetylene.

Pyrazolato Metal Complexes – Synthesis, Characterization, and X-ray Crystal Structures of Heterotrimetallic Re–M2 Derivatives (M = Cu, Ag, Au)

By treating [(CO)3Re(Hpz)2(pz)] (Hpz = pyrazole) with [Cu(CH3CN)4]BF4, AgNO3, or [Au(tht)Cl] (tht = tetrahydrothiophene) in acetonitrile in the presence of Et3N, the corresponding trinuclear complexes {(CO)3Re(pz)3[M(CH3CN)]2} (1a–c) have been obtained. Treatment of complexes 1a–c with cyclohexyl isocyanide (c-C6H11NC) afforded the derivatives {(CO)3Re(pz)3[M(c-C6H11NC)]2} (2a–c). Complexes 2a–c have been characterized in solution by 1H-NMR spectroscopy and in the solid state by single-crystal X-ray diffraction analysis.

The stepwise interaction of [(phen)(Ph3P)Cu(O2COH)] with pyrazoles and CO2: Synthesis and reactivity of copper(I) pyrazolecarboxylates

Abstract Reactions between [(phen)(Ph 3 P)Cu(O 2 COH)] ( A , phen = 1,10-phenanthroline) and 3,5-dimethyl- pyrazole (pzH) or pyrazole (PzH) in acetone afford the insoluble copper(I) pyrazolates [Cu(pz)] n or [Cu(Pz)] n and red solutions. The action of CO 2 on these suspensions at low temperature yields new copper(I) pyrazolecarboxylates of formula [(phen)(Ph 3 P)Cu(O 2 Cpz)(H 2 O)] ( 1a ) or [(phen)(Ph 3 P)Cu(O 2 CPz)(H 2 O)] ( 1b ) respectively. When heated at 80 °C under vacuum as solid, 1a gives [(phen)(Ph 3 P)Cu(pz)] ( 2 ). The latter can be also obtained by N 2 bubbling at 0 °C through suspensions of 1a . At higher temperatures the decarboxylation reaction of 1a is accompanied by the loss of phen and PPh 3 , [Cu(pz)] n being recovered as the final product. By stirring an acetone suspension of 1a under a CO 2 atmosphere, free pzH and an orange product analysing as [(phen)(Ph 3 P)Cu(O 2 COH)] ( 3 ) were isolated. Complex 3 , although having the same stoichiometry as A , was shown to exhibit spectroscopic and some chemical properties quite different from those of A . The action of pzH under an inert atmosphere on 3 (molar ratio pzH/ 3 = 1), allowed the isolation of 1a , without carbon dioxide evolution. Excess phen on polymeric [Cu(pz)] n causes the formation of [(phen)Cu(pz)] 2 ( 4 ), probably containing a bridging pyrazolate group. The latter has been reacted with CO 2 in the presence of pzH (molar ratio pzH/ 4 >1) obtaining the pyrazolecarboxylato complex 5 , [(phen)(pzH)Cu(O 2 Cpz)]. The neutral pyrazole ligand present in 5 , weakly bound to the metal center, can be easily displaced by triphenyl- phosphine, with formation of 1a , or by cyclohexyl- isocyanide. In the latter case, displacement of both pzH and phen has been observed, and the new pyrazolyl complex 6 [(CyNC)Cu(pz)] 2 , formed. Gas volumetric and thermogravimetric measurements and IR spectra are reported and discussed. A plausible mechanism by which complexes 1 are formed, is also reported.

Oxidation reaction of the copper(I) phenoxo complex [(phen)(Ph3P)Cu(OPH)]: The formation of the copper(II) derivative [(phen)Cu(OPh(OC6H4-2-(OH)], having a catecholate group derived from phenol hydroxylation reaction

The copper(I) bicarbonato complex [(phen)(Ph3P)Cu(O2COH)] (1) (phen = 1,10-phenanthroline) reacts under nitrogen with phenol giving the copper(I) phenoxo derivative [(phen)(Ph3P)Cu(OPh)] (2). Complex 2 was shown to undergo a facile hydrolysis, PhOH being released. The action of moist CO2 on 2 allowed the isolation of the starting bicarbonato complex 1. The reaction of 1 with excess phenol under an oxygen atmosphere, gave the unexpected copper(II) derivative [(phen)Cu(OPh)(OC6H4-2-(OH)] (3). The catecholate group, OC6H4-2-(OH), which is present in complex 3, originates from a phenol hydroxylation reaction assisted by the copper center. The same complex 3 has been also obtained by reacting 2 with excess PhOH under oxidative conditions. The bicarbonato complex 1 reacts with catechol under an oxygen atmosphere giving [(phen)Cu(cat)] (4) or the bis(catecholate)copper(II) derivative, (phen)Cu[OC6H4-2-(OH)]2 (5), depending on the molar ratio copper/catechol. The copper(II) complexes 3, 4 and 5 were shown to be sensitive to water; in the case of compounds 3 and 5 a reaction takes place, the CuOPh (complex 3) and one of the CuOC6H4-2-(OH) (complex 5) groups being involved, phenol (complex 3) and catechol (complex 5) being respectively released. Complex 4, owing to its tendency to retain water of crystallization, converts into [(phen)Cu(cat)]H2O (6). From the hydrolysis reactions of 3 and 5, Download full-size image the catecholato derivative 6 was always obtained, probably through the intermediate formation of the copper(II) hydroxo-catecholate complex [(phen)Cu(OH)(OC6H4-2-(OH))].

Tuning the fluorescence emission in mononuclear heteroleptic trigonal silver(I) complexes

Seven mononuclear heteroleptic silver(I) complexes, [Ag(N∩N)(PR3)](NO3) (N∩N = 2-(1-(pyridin-2-yl)imidazo[1,5-a]pyridin-3-yl)phenol; P = PPh3 (1), PMe2Ph (2), PMePh2 (3), P(p-tolyl)3 (4), P(nBu)3 (5), P(OPh)3 (6), and P(OEt)3 (7)), have been prepared and characterized. In these compounds, N∩N acts as a bidentate ligand with the pyridine ring and the pyridine-like nitrogen of the imidazo[1,5-a]pyridine group. The coordination around silver is completed by the monodentate phosphine, the nitrate anion being not bound to the metal, which then displays a trigonal planar geometry as confirmed by the X-ray crystal structure of compounds 1, 2, 5 and 6. 31P{1H} NMR and conductivity measurements were performed to settle on the behavior of these complexes in solution. The photophysical properties of these species have been investigated, both in solution and in the solid state: they showed intense fluorescence when excited with UV light, with λmax of emission comprised between 440–460 nm (in solution) and 460–498 nm (solid state) and lifetime decay of a few nanoseconds. In the solid state, a reasonable tuning of the emission is observed according to the electronic features of the coordinated phosphine.

Synthesis and ab-initio XRPD structure of group 12 imidazolato polymers

Two new 3D homoleptic binary imidazolates, Cd(im)2 and Hg(im)2 (Him = imidazole), as well as [Hg(im)]NO3, containing 1D polycations of [Hg(im)]n(n+) formulation, have been prepared and characterized by ab-initio XRPD methods.