1,720,981 research outputs found
Synthesis and X-ray powder diffraction characterization of tetra- and hexa-imidazole complexes of magnesium(II)
No full textX-ray powder diffraction data for two ionic salts contg. imidazole (Him) complexes of the magnesium(II) ion, [Mg(Him)4(H2O)2]Cl2 and [Mg(Him)6](NO3)2, are reported. Their crystal and mol. structures were detd. by simulated annealing and full-profile Rietveld refinement methods. [Mg(Him)4(H2O)2]Cl2 was found to crystallize in the monoclinic system with space group C2/c, a=12.3980(3) A, b=11.0234(2) A, c=14.4691(3) A, and =107.024(1). [Mg(Him)6](NO3)2 crystallizes in the trigonal R-3 space group with a=b=12.4631(4) A and c=14.9449(6) A. Both species contain centrosym. complexes, and Mg is octahedrally coordinated by six imidazoles, as in [Mg(Him)6](NO3)2, or by four imidazoles and two water mols., as in [Mg(Him)4(H2O)2]Cl2. Addnl. analytic, thermogravimetric, calorimetric, and spectroscopic characterizations were also performed
Self-assembled rings and coordination polymers starting from [RhCl2(CO)2] and diphosphane ligands
No full textIn the past few years we have reported on the synthesis of some 1D coordination polymers based on Rh(I) and Ir(I) halocarbonyls and some diphosphano ligands, confirming the high versatility of these ligands in coordination self-assembly.
Significant results obtained with diphosphanes of general formula PPh2(CH2)nPPh2 (n=5-12) are here summarized. Generally, the formation of coordination rings is observed and sometimes these are the only species isolated; interestingly, rings with n=6 and 8, subsequently evolve to the corresponding polymers, probably through a reaction of ring-opening polymerization
Tetrairidium carbonyl clusters linked by 1,6-bis(diphenylphosphane)hexane (dpphex): synthesis and solid state structure of {[Ir4(CO)11]2(dpphex)} and [Ir4(CO)10(dpphex)]2.
No full textCarbonyl complexes of Rh(I) and Ir(I) and P-donor ligands as useful ‘‘building blocks’’ for the self-assembly of new organometallic polymers
No full textWe report here on three new 1-D polymeric species, obtained by self-assembly of Rh(I) and Ir(I) complexes of general formula [M(CO)2Cl2]2 (M= Rh, Ir) with bidentate phosphine ligands as 1,2-bis(diphenylphosphino)acetylene (dppa) and trans-1,2-bis(diphenylphosphino)ethene (dppethe)
Rhodiumcarboyl and diphosphine based 1D-polymers : a family of Vaska type compounds in polymeric form
No full textSynthesis, structure and thermal behaviour of two magnesium complexes containing the 1,4-bis(5-tetrazolyl)benzene ligand
No full textThe reaction between the 1,4-bis(5-tetrazolyl)benzene ligand (H2btb) and different Mg salts allowed the recovery of two different mol. salts, [Mg(H2O)6](btb) (1) and [Mg(H2O)6](Hbtb)22H2O (2). These cryst. materials were fully characterized by spectroscopic, thermal and diffraction methods. In both cases the octahedrally coordinated hexaaquo Mg(II) ions are linked through several strong H-bond interactions of the OHN type to the btb anions, completely or partially deprotonated in 1 and 2, resp. The thermal anal. established that, in both cases, all H2O mols. are lost <200. The process is completely reversible upon exposure to H2O-satd. atm. Unfortunately, the anhyd. phases are amorphous, and no structural information could be derived form the authors' PD traces, even if a no. of partially cryst. intermediates, formed during the dehydration processes, were obsd. by thermodiffractometric methods
Synthesis of oligomeric and polymeric Rh(I) halocarbonyl diphosphine compounds
No full textIn the last years, we pursued the synthesis of coordination polymers starting from the Rh(I) halocarbonyl [RhCl2(CO)2]- and different diphosphine ligands reporting some successful example of 1D polymeric structures.1,2
Significant results obtained with diphosphines of general formula PPh2(CH2)nPPh2 (n=5-12) are here summarized. Generally, the formation of coordination rings is observed and sometimes this is the only species isolated; interestingly, rings with n=6 and 8, subsequently evolve to the corresponding polymers, probably through a reaction of ring-opening polymerization
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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