Loading silica with metals (palladium or platinum) under mild conditions by using well-defined molecular precursors.

The loading of pre-treated amorphous silica with platinum or palladium was carried out by using the molecular precursors Pt2(micro-Cl)2Cl2(CO)2, or Pd2(micro-Cl)2Cl2(CO)2, respectively, which contain the required amount of coordinated CO to carry out the formation of the metal particles upon contact with moisture. The reactivity of the well-soluble mononuclear platinum complex cis-PtCl2(CO)2 with stoichiometric amounts of water was investigated either under N2 or CO. The metal nanoparticles produced on the silica matrix have been characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and transmission electron microscopy (TEM).

Nanostructured copper oxide on silica-zirconia mixed oxides by chemical implantation.

N,N-Dialkylcarbamato complexes of copper(II), [Cu(O(2)CNR(2))(2)] (R = All = allyl, C(3)H(5); iPr, CH(CH(3))(2)) were prepared with the aim of functionalizing silica and nanostructured silica-zirconia matrices. The mixed matrices for the grafting reactions were prepared by copolymerizing MAPTMS (methacryloxypropyltrimethoxysilane), the precursor for the silica matrix, with the zirconium tetranuclear derivative [Zr(4)O(2)(OMc)(12)] (OMc = methacrylate), the precursor for the zirconia nanoparticles. Suspension of the silica and silica-zirconia matrices in a solution of the copper dialkylcarbamate led to the functionalization of the respective substrates.

N,N-Di-iso-propylcarbamato complexes of boron.

N,N-di- iso-propylcarbamato derivatives of boron(III) have been synthesized from di-iso-propylamine and boron trichloride in the presence of carbon dioxide. With a large excess of amine, a single boron product was obtained, [NH2i)Pr2][B(O2CNiPr2)4], 1, while with a lower excess a mixture of 1 and of the dinuclear derivative [B2(O2CNiPr2)6], 2, was produced. By heating in vacuo at 60 degrees C, solid 1 slowly converted to 2.

Simple preparations of Pd6Cl12, Pt6Cl12, and Qn[Pt2Cl8+n], n=1, 2 (Q=TBA+, PPN+) and structural characterization of [TBA][Pt2Cl9] and [PPN]2[Pt2Cl10].C7H8.

The hexanuclear Pd6Cl12, i.e., the crystal phase classified as beta-PdCl2, was obtained by reacting [TBA]2[Pd2Cl6] with AlCl3 (or FeCl3) in CH2Cl2.

Bis(arylimino)pyridine derivatives of Group 4 metals: preparation, characterization and activity in ethylene polymerization.

Titanium tetrachloride reacts with 2,6-bis[(1-phenylimino)ethyl]pyridine, 1, and 2,6-bis[1-(2,6-diisopropylphenylimino)ethyl]pyridine, 2, giving the adducts of general formulae [Ti1Cl3]Cl, 3, and [Ti2Cl3]Cl, 6, the latter through the intermediacy of the covalently bonded [Ti2Cl4], 4. Heating 6 leads to reduction to the titanium(III) derivative [Ti2Cl3], 12, the latter characterized by X-ray diffraction methods. The reaction of [Ti1Cl3]Cl with a toluene solution of MAO proceeds with methylation at the ortho-position of the pyridine ring to give the titanium(iv) derivative [Ti(C22H21N3)Cl3], 8.

Bis-qtpy (qtpy = 2,2':6',2'':6'',2'"-quaterpyridine) metal complexes, [M(qtpy)(2)]2+.

Reactions of perchlorates of iron(II), nickel(II), and zinc(II) with 2,2':6',2'':6'',2'"-quaterpyridine (qtpy) gave the first crystallographically established bis-qtpy metal complexes of formula [M(qtpy)(2)][ClO(4)](2) (M = Fe, Ni, Zn). Coordination of two terdentate quaterpyridines to the same center produces a distorted octahedron of six nitrogen atoms around the metal, leaving two pendant pyridyl groups, one for each quaterpyridine. For the diamagnetic zinc system, an NMR investigation has been carried out in order to establish the conditions to obtain the intermediate mono-qtpy complex, of formula [Zn(qtpy)(H(2)O)(2)][ClO(4)](2), which has also been crystallographically established.

Mono- and dinuclear complexes of sulfones with the tetrachlorides of group 4.

The reactions of dialkyl sulfones [R(2)SO(2): R = Me, Et, Ph, R(2)=-(CH(2))(4)-] with the metal tetrachlorides of Group 4 [MCl(4): M = Ti, Zr, Hf] give different products mainly depending on the sulfone/M molar ratio. Compounds of formula [M(2)Cl(8)(R(2)SO(2))(2)][M = Ti, R(2)=-(CH(2))(4)-; M = Zr, R = Et, R = Ph] and [MCl(4)(R(2)SO(2))(2)](sulfone/M = 2)[M = Ti, R = Me; M = Zr, R = Me, R = Ph, R(2)=-(CH(2))(4)-; M = Hf, R = Me, R(2)=-(CH(2))(4)-] have been obtained. By X-ray diffraction methods the dinuclear titanium and zirconium adducts, [Ti(2)Cl(8)(mu-sulfolane-O,O')(2)] and [Zr(2)Cl(8)(mu-Ph(2)SO(2)-O,O')(2)] have been established to contain bridging sulfone and hexacoordinated metal centres, while the mononuclear zirconium complex [ZrCl(4)(Me(2)SO(2))(2)] has cis-monodentate sulfones in a slightly distorted octahedral geometry.

Coordination of cyclo-octasulfur and cyclo-heptaselenium to dinuclear rhenium(I) systems.

By substitution reactions of the coordinated THF ligands of Re(2)(mu-X)(2)(CO)(6)(THF)(2) by elemental chalcogens (S(8) and red selenium), the complexes Re(2)(mu-X)(2)(CO)(6)(S(8)) (X = Br, 1; I, 2), and Re(2)(mu-X)(2)(CO)(6)(Se(7)), (X = I, 3; Br, 4) have been prepared. Binuclear compound 3 was crystallographically established to be a coordination compound of cyclo-heptaselenium, two adjacent selenium atoms of the Se(7) ligand [Se-Se distance, 2.558(3) A] being bonded to rhenium(I), at an average Re-Se distance of 2.

New mu-oxo octanuclear complexes of 3d elements stabilized by dialkylcarbamato ligands. Synthesis and X-ray crystal and molecular structures.

The octanuclear aggregates M(8)(mu(4)-O)(2)(O(2)CN(i)()Pr(2))(12) [M = Mn(II) 1, Co(II) 2, Ni(II) 3] have been prepared in good yields by controlled hydrolysis of the corresponding metal carbamate precursors [M(O(2)CN(i)()Pr(2))(2)](n)(). X-ray analysis has shown compounds 1-3 to be isostructural. The core of 2 contains two distorted [M(4)O] tetrahedra related by an inversion center.

Synthesis and Crystal Structure of a Self-Assembled, Octanuclear Oxo-Tantalum(V) Derivative Containing the First Example of a Transition Metal M(8)(&mgr;-O)(12) Cage.

By reduction with CoCp(2) in THF or toluene, the tantalum(V) chlorocarbamato complex TaCl(2)(O(2)CNEt(2))(3), 1, gives high yields of the tantalum(III) N,N-diethylcarbamate, Ta(O(2)CNEt(2))(3), 2. On the other hand, good yields of the octanuclear &mgr;-oxo-N,N-diethylcarbamato cage compound Ta(8)(&mgr;-O)(12)(O(2)CNEt(2))(16), 3, were secured by reaction of 1 with sodium in THF. Compound 3 has been characterized by analytical and spectroscopic methods and by X-ray diffractometry.