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The reactivity of mono-substituted HC=CR (R =Ph. a; CH2OH, b; CH2CH2CH2CH3, c) and di-substituted RC=CR (R = CH2CH3, d; CO2CH3, e; Ph. f) acetylenes was studied in supercritical carbon dioxide (scCO(2)) using the easily available complex CpCo(CO)(2) as catalyst. The reaction of phenylacetylene produced a mixture of the isomeric cyclotrimers 1,3,5- (2a) and 1.2,4-triphenylbenzene (2a '). in a 1:5 ratio, and traces of cobaltcyclopentadienone complexes CPCO(eta (4)-C4H2[Ph](2)CO) (6a, mixture of isomers). The possible product formed by the incorporation of CO, to alkynes, i.e. diphenylpyrone (7a) was not observed. The reaction of the cobaltacyclopentadiene complex CpCo(1.4-sigma -C-4[Ph](4))(PPh)(3) (8f), in scCO(2), was performed. No insertion of CO2 into the Co-C a-bond to form tetraphenylpyrone (7f) by reductive elimination was observed, instead the cobaItcyclobutadiene Complex CpCo(eta (4)-C-4[Ph](4)) (9f) was formed. In the reactions with other alkynes, lower yields were obtained in general, except in the cyclotrimerisation of the highly activated alkyne, propargyl alcohol (b). Reaction of the non-activated alkynes, 1-hexyne (c) and 3-hexyne (d), produced complex mixtures of cobalt complexes in low yield in which the alkyne was coordinated to cobalt. Finally, the highly hindered diphenylacetylene (f) gave a mixture of the known Complexes CpCo(eta (4)-C-4[Ph](4)) (9f) and CpCo(eta (4)- C-4[Ph](4)CO) (6f) in agreement with the results observed in conventional organic solvents. (C) 2001 Elsevier Science B.V, All rights reserved.

The donor strengths of the following triarylphosphine ligands P(Ar)(2)(Ar') (Ar = Ar' = 4-Me3SiC6H4, 1b; 4-Me3CC6H4, 1d; 4-F3CC6H4, 1e; Ar = C6H5, Ar' = 4-Me3SiC6H4, 1c) have been evaluated experimentally and theoretically. The measurements of the J(P-Se) coupling constants of the corresponding synthesised selenides Se=P(Ar)(2)(Ar'), 2b, c and the DFT calculation of the energies of the phosphine lone-pair ( HOMO) reveal insignificant influence on the electronic properties of the substituted phosphines when the trimethylsilyl group is attached to the aryl ring, in marked contrast to the strong electronic effect of the trifluoromethyl group. These triarylphosphine ligands P(Ar)(2)(Ar') reacted with (eta(5)-C5H5)Co(CO)(2), (eta(5)-C5H5)Co(CO)I-2 or PdCl2 to yield the new compounds (eta(5)-C5H5)Co(CO)[P(Ar)(2)(Ar')], 3b, d; (eta(5)-C5H5)COI[P(Ar)(2)(Ar')], 4b-e; and PdCl2[P(Ar)(2)(Ar')](2), 5b, c, respectively. These complexes have been characterized and their spectroscopic properties compared with those reported for the known triphenylphosphine complexes. Again, the contrast of the P-31 NMR and C-13 NMR chemical shifts or C-O or M-Cl stretching frequencies, when applied, does not show an important electronic effect on the metal complex of the trimethylsilyl substituted phosphines with respect to P(C6H5)(3) derivatives. Solubility measurements of complexes 3a and 3b in scCO(2) were performed. We conclude that Me3Si groups on the triarylphosphine improve the solubility of the corresponding metal complex in scCO(2).

The two new pincer azomethine-thiophene ligands (N,NE',N,NE')-N,N'-(thiophene-2,5-diylbis(methan-1-yl-1-ylidene))bis(naphathalen-2-ylmethanamine) (L1) and (E)-(4,6-dihydropyren-1-yl)-N-((5-((E)-(pyren-1-ylmethylimino)ethyl)thiophen-2-yl)methylene)methanamine (L2), their absorption, fluorescence and MALDI-TOF-MS spectroscopic studies are described. The two systems synthesised combine the emissive probes pyrene and naphthyl with the good chelating properties of a tridentate SN2 donor-set from a thiophene Schiff-base ligand. Both ligands gave analytically pure solid complexes with Ni(II) and Pd(II) salts. The bichromophoric pyrene derivative L2 presents two emission bands in solution, one corresponding to the monomer species and a red-shifted band attributable to the intramolecular excimer. Ni(II) and Pd(II) complexation affects the conformation in solution, increasing the monomer emission at the expense of the excimer band; this effect could be explored in metal ion sensing. System L1 behaves as a non emissive probe. In situ complexation reactions followed by MALDI-TOF-MS spectrometry without matrix support have also been performed; these experiments show that L1 could be a potential chemosensor for Ni(II) and Pd(11). (c) 2007 Elsevier B.V. All rights reserved.

A novel flexible tripodal ligand derived from 3-methylindole, ("InTREN" L), and its mononuclear Zn(II), Cu(II), Ni(II), Hg(II) and Pd(II) complexes are described. All compounds gave analytically pure solid samples. Characterisation of the compounds was accomplished by (1)H NMR, IR and absorption spectroscopies, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and elemental analysis and their geometry optimized using density functional theory (DFT).Time-dependent-density functional theory (TD-DFT) calculations have been used to assign the lowest energy absorption bands of the free ligand and the Zn(II) complex. The system is a very good candidate for in situ recognition/coordination effects by MALDI-TOF-MS spectrometry and absorption spectroscopy. The presence of three indole groups in InTREN opens up the possibility to synthesize new three-dimensional self-assembly supramolecular structures. (C) 2008 Elsevier B.V. All rights reserved.

The reaction between [Cu(NCMe)(4)][PF6] and 1,1'-bis-(diphenylphosphino)-ferrocene (dppf) in several ratios, solvents, and conditions led to the synthesis and structural characterization of the Cu(I) complexes [Cu(dppf)(Odppf)] [PF6] (1), [(dppf)Cu(mu -dppf)Cu(dppf)][PF6](2) (2), and [(dppf)Cu(mu -Cl)(2)Cu(dppf)] (3). Although 1 and the cation in 2 were known, the first was structurally characterized for the first time, exhibiting a significant asymmetry in the coordination sphere of Cu(I)) owing to the presence of oxygen. In 2, the PF6- anion led to an interesting crystal packing with large open channels containing water. Finally, DFT calculations on a model of 3 showed that its HOMO exhibits, besides Fe, a significant Cu and Cl character, which is reflected in its electrochemical properties.

{Zinc alkyl cations supported by N,N-BIAN-type bidentate ligands were found to be highly active in the immortal ROP of epsilon-caprolactone to yield narrowly disperse and chain length-controlled poly(epsilon-caprolactone), whether in solution or bulk polymerization conditions.}

A series of cobalt(II) compounds of the type [CoX2(alpha-diimine)] were synthesised by direct reaction of anhydrous CoCl2 or CoI2 and the corresponding alpha-diimine ligand, in CH2Cl2: [CoI2(o,o',p-Me3C6H2-DAB)] ( 1), [ CoI2(o,o'-(Pr2C6H3)-Pr-i-DAB)] ( 2), ( where Ar-DAB = 1,4-bis(aryl)-2,3-dimethyl-1,4-diaza-1,3-butadiene), and [CoCl2(o,o',p-Me3C6H2- BIAN)] (3), [CoCl2(o,o'- (Pr2C6H3)-Pr-i-BIAN)] (4), and [CoI2(o,o'-(Pr2C6H3)-Pr-i-BIAN)] (5) (where Ar-BIAN = bis(aryl) acenaphthenequinonediimine). All compounds were characterised by elemental analyses, IR, mass spectrometry, and X-ray diffraction whenever possible. The crystal structures of compounds 2-4 showed, in all cases, distorted tetrahedral geometries about the Co, built by two halogen atoms and two nitrogen atoms of the alpha-diimine ligand. Compounds 3 and 4, as well as [ CoCl2(o,o',p-Me3C6H2-DAB)] (1a), and [ CoCl2( o,o'- (Pr2C6H3)-Pr-i- DAB)] (2a), were activated by methylaluminoxane (MAO) and tested as catalysts for ethylene polymerisation, showing low catalytic activities. Selected polyethylene ( PE) samples were characterised by H-1 and C-13 NMR and FT-IR spectroscopies, and by differential scanning calorimetry (DSC), revealing branching microstructures (2.5-5.5%). (c) 2007 Elsevier B. V. All rights reserved.

New compounds of the general formulas [M(Ar-BIAN)(2)]BF(4) and [M(Ar-BIAN)(NCMe)(2)]BF(4), where M=Cu(1) or Ag(1) and Ar-BIAN = bis(aryl)acenaphthenequinonediimine, were synthesized by the direct reaction of [Cu(NCMe)(4)]BF(4) or [Ag(NCMe)(4)]BF(4) with the corresponding Ar-BIAN ligand in dried CH(2)Cl(2). The synthesized compounds are [M(o, d, p-Me(3)C(6)H(2)-BIAN)(2)]BF(4) where M = Cu(1) (1) and Ag(1) (2), [M(o,d-iPr(2)C(6)H(3)-BIAN)(NCMe)(2)]BF(4) where M = Cu(1) (3) and Ag(1) (4), and [Ag(o,d-iPr(2)C(6)H(3)-BIAN)(2)]BF(4) (5). The crystal structures of compounds 1-3 and 5 were solved by singlecrystal X-ray diffraction. In all cases copper(I) or silver(I) are in a distorted tetrahedron that is constructed from the four nitrogen atoms of the two a-diimine ligands or, in 3, from one a-diimine ligand and two acetonitrile molecules. All compounds were characterized by elemental analyses, matrix-assisted laser desorption ionization time-of-flight mass spectrometry, and IR, UV-vis, and (1)H NMR spectroscopy. The analysis of the molecular geometry and the energetic changes for the formation reactions of the complexes, in a CH(2)Cl(2) solution, were evaluated by density functional theory calculations and compared with the experimental results.

Cobalt compounds of the general formula [COX2(alpha-diimine)], where X = Cl or I and the alpha-diimines are 1,4-diaryl-2,3-dimethyl-1,4-diaza-1,3-butadiene (Ar-DAB) and bis(aryl)acenaphthenequinonediimine (Ar-BIAN) were synthesized by the direct reaction of the anhydrous cobalt salts CoCl2 or CoI2 and the corresponding alpha-diinline ligand in dried CH2Cl2. The synthesized compounds are [Co(Ph-DAB)Cl-2] (1a), [Co(o,o',p-Me3C6H2-DAB)Cl-2] (1b), and [Co(o,o'iPr(2)C(6)H(3)-DAB)Cl-2] (1c) with the ligands Ar-DAB, and also [Co(o,o',p-Me3C6H2-BIAN)I-2] (2'b) with the ligand Ar-BIAN. The crystal structures of all the compounds were solved by single-crystal X-ray diffraction. In all cases the cobalt atom is in a distorted tetrahedron, which is built up of two halide atoms and two nitrogen atoms of the alpha-dimune ligand. X-band EPR measurements of polycrystalline samples performed on compounds 1b, 1c, and 2'b indicate a high-spin Col, ion (S = 3/2) in an axially distorted environment. Single-crystal EPR experiments on compounds 1b and 1c allowed us to evaluate the orientation of the g tensor in the molecular frame. (c) Wiley-VCH Verlag GmbH & Co.

{{Abstract A variety of N-heterocyclic carbene (NHC) zinc adducts of the type NHC-ZnMe2 {[}2a