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Gabor Laurenczy

Publications and source records attributed to Gabor Laurenczy.

4 recordsLinked to original sources
PubMed2006

Biphasic hydrosilylation in ionic liquids: a process set for industrial implementation.

The biphasic hydrosilylation of 1-hexadecene with siloxane B9800 in a range of ionic liquids is reported. Of the ionic liquids tested, [C(4)py][BF(4)] and [C(4)-3-pic][BF(4)] offer the optimum compromise between activity and catalyst retention. Several platinum precatalysts were screened, of which K(2)PtCl(4) and Pt(PPh(3))(4) were found to give the best performance; the former provides the highest activity, while the latter offers higher stability and recyclability, and depending on the conditions, both can afford either homogeneous or soluble nanoparticle catalysts as the active species. A number of reaction parameters were varied, and the effects of oxygen, water, and chloride impurities on the reaction were studied. In addition, since nanoparticle catalysts were observed, various strategies to stabilize nanoparticles were screened, but none of them resulted in a superior catalytic system.

Journal Article↗
PubMed2005

Coordination chemistry of a new rigid, hexadentate bispidine-based bis(amine)tetrakis(pyridine) ligand.

The hexadentate bispidine-based ligand 2,4-bis(2-pyridyl)-3,7-bis(2-methylenepyridine)-3,7-diazabicyclo[3.3.1]nonane-9-on-1,5-bis(carbonic acid methyl ester), L(6m), with four pyridine and two tertiary amine donors, based on a very rigid diazaadamantane-derived backbone, is coordinated to a range of metal ions. On the basis of experimental and computed structural data, the ligand is predicted to form very stable complexes. Force field calculations indicate that short metal-donor distances lead to a buildup of strain in the ligand; that is, the coordination of large metal ions is preferred. This is confirmed by experimentally determined stability constants, which indicate that, in general, stabilities comparable to those with macrocyclic ligands are obtained with the relative order Cu(2+) > Zn(2+) >> Ni(2+) < Co(2+), which is not the typical Irving-Williams behavior. The preference for large M-N distances also emerges from relatively high redox potentials (the higher oxidation states, that is, the smaller metal ions, are destabilized) and from relatively weak ligand fields (dd-transition, high-spin electronic ground states). The potentiometric titrations confirm the efficient encapsulation of the metal ions since only 1:1 complexes are observed, and, over a large pH range, ML is generally the only species present in solution.

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PubMed2004

Reactions of [Ru(H(2)O)(6)](2+) with water-soluble tertiary phosphines.

In aqueous solutions under mild conditions, [Ru(H(2)O)(6)](2+) was reacted with various water-soluble tertiary phosphines. As determined by multinuclear NMR spectroscopy, reactions with the sulfonated arylphosphines L =mtppms, ptppms and mtppts yielded only the mono- and bisphosphine complexes, [Ru(H(2)O)(5)L](2+), cis-[Ru(H(2)O)(4)L(2)](2+), and trans-[Ru(H(2)O)(4)L(2)](2+) even in a high ligand excess. With the small aliphatic phosphine L = 1,3,5-triaza-7-phosphatricyclo-[3.3.1.1(3,7)]decane (pta) at [L]:[Ru]= 12:1, the tris- and tetrakisphosphino species, [Ru(H(2)O)(3)(pta)(3)](2+), [Ru(H(2)O)(2)(pta)(4)](2+), [Ru(H(2)O)(OH)(pta)(4)](+), and [Ru(OH)(2)(pta)(4)] were also detected, albeit in minor quantities. These results have significance for the in situ preparation of Ru(II)-tertiary phosphine catalysts. The structures of the complexes trans-[Ru(H(2)O)(4)(ptaMe)(2)](tos)(4)x2H(2)O, trans-[Ru(H(2)O)(4)(ptaH)(2)](tos)(4)[middle dot]2H(2)O, and trans-mer-[RuI(2)(H(2)O)(ptaMe)(3)]I(3)x2H(2)O, containing protonated or methylated pta ligands (ptaH and ptaMe, respectively) were determined by single crystal X-ray diffraction.

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