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Synthesis and structural characterization of isomeric 'lantern-shaped' platinum(III) complexes of formula [Pt-2(PPh3)X{N(H)C(R)O}(4)](NO3)(2) (X = PPh3, H2O)
No full textThe platinum(III) lantern type complexes [Pt-2(PPh3)(2){N(H)C(R)O}(4)](NO3)(2) [R =Me (1), Bu-t (2)], and [Pt-2(H2O)(PPh3)- {N(H)C(Bu-t)O}(4)](NO3)(2) (3) were synthesized and characterized by H-1 NMR and X-ray crystallography (2 and 3). The compounds can give rise to formation of isomers differing for the sets of equatorial donor atoms around each platinum, (NO)-O-3/NO3 orN(2)O(2), and, in the case of N2O2, for the cis or trans geometry. The effect of the anion upon the chemical shifts of NH protons was studied for NO3-, BF4-, and ClO4-. The stability of phosphine axial ligands in the complexes (NO)-O-3/NO3-[Pt-2(PPh3)(2){N(H)C(R)O}(4)](NO3)(2) as a function of the set of donor atoms was also studied. The complex (NO)-O-3/NO3-3 is the fist non-symmetric lantern-type platinum dimer to be characterized by X-ray diffraction. Comparison of the platinum/axial ligand bond distances in different complexes of this type allows to conclude that two factors contribute to the lengthening of axial bonds: the strong trans labilizing effect of the intermetallic bond and the trans-influence of the axial ligand on the second platinum unit
Processo di sintesi di complessi di platino con imminoeteri e loro utilizzazione come agenti antitumorali e agenti modificanti le basi nucleotidiche
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H-Bond interactions between the NH of carrier ligand (Me3dien) and the O6 or the 5'-phosphate of guanine nucleotides in platinum complexes with a single guanine ligand.
No full textSynthesis and characterisation of the amidine complexes trans-[PtCl(NH3) {HN=C(NH2)R}(2)]Cl (R = Me, Ph, CH2Ph) derived from addition of NH3 to the coordinated nitriles in trans-[PtCl2(N CR)(2)]
No full textThe di-nitrile complexes trans-[PtCl2(NCR)(2)] (R = Me, Ph, CH2Ph) react with an excess of gaseous NH3 in CH2Cl2 at -10 degrees C to form, in high yield, the corresponding di-amidine complexes trans-[PtCl(NH3){HN=C(NH2)R}(2)]Cl in which also one chlorine ligand has been displaced by NH3. The H-1 NMR spectra in DMSO showed the formation of different species which were characterized through NOESY, TOCSY and H-1/C-13 heteronuclear correlations as trans-[Pt(NH3){HN=C(NH2)R}(2)(DMSO)]Cl-2 and trans-[PtCl{HN=C(NH2)R}(2)(DMSO)]Cl. (c) 2005 Elsevier B.V. All rights reserved
Rilevanza dei legami ad idrogeno nell'interazione intramolecolare fra i gruppi NH del legante amminico e l'O6 o il 5'-fosfato di un residuo guaninico in complessi di platino.
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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