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Alvarez W, Asaro F, Michel HV, Alvarez LW. Iridium anomaly approximately synchronous with terminal eocene extinctions. Science 2010; 216:886-8. [PMID: 17819180 DOI: 10.1126/science.216.4548.886] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
An iridium anomaly has been found in coincidence with the known microtektite level in cores from Deep Sea Drilling Project site 149 in the Caribbean Sea. The iridium was probably not in the microtektites but deposited simultaneously with them; this could occur if the iridium was deposited from a dust cloud resulting from a bolide impact, as suggested for the anomaly associated with the Cretaceous-Tertiary boundary. Other workers have deduced that the microtektites are part of the North American strewn tektite field, which is dated at about 34 million years before present, and that the microtektite horizon in deep-sea cores is synchronous with the extinction of five radiolarian species. Mass extinctions also occur in terrestrial mammals within 4 million years of this time. The iridium anomaly and the tektites and microtektites are supportive of a major bolide impact about 34 million years ago.
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Alvarez LW, Alvarez W, Asaro F, Michel HV. Extraterrestrial cause for the cretaceous-tertiary extinction. Science 2010; 208:1095-108. [PMID: 17783054 DOI: 10.1126/science.208.4448.1095] [Citation(s) in RCA: 653] [Impact Index Per Article: 46.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Platinum metals are depleted in the earth's crust relative to their cosmic abundance; concentrations of these elements in deep-sea sediments may thus indicate influxes of extraterrestrial material. Deep-sea limestones exposed in Italy, Denmark, and New Zealand show iridium increases of about 30, 160, and 20 times, respectively, above the background level at precisely the time of the Cretaceous-Tertiary extinctions, 65 million years ago. Reasons are given to indicate that this iridium is of extraterrestrial origin, but did not come from a nearby supernova. A hypothesis is suggested which accounts for the extinctions and the iridium observations. Impact of a large earth-crossing asteroid would inject about 60 times the object's mass into the atmosphere as pulverized rock; a fraction of this dust would stay in the stratosphere for several years and be distributed worldwide. The resulting darkness would suppress photosynthesis, and the expected biological consequences match quite closely the extinctions observed in the paleontological record. One prediction of this hypothesis has been verified: the chemical composition of the boundary clay, which is thought to come from the stratospheric dust, is markedly different from that of clay mixed with the Cretaceous and Tertiary limestones, which are chemically similar to each other. Four different independent estimates of the diameter of the asteroid give values that lie in the range 10 +/- 4 kilometers.
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Alvarez W, Alvarez LW, Asaro F, Michel HV. The end of the cretaceous: sharp boundary or gradual transition? Science 2010; 223:1183-6. [PMID: 17742934 DOI: 10.1126/science.223.4641.1183] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Evidence indicates that the Cretaceous-Tertiary boundary is very sharp, and, within the limits of resolution, it is apparently synchronous at the various boundary localities. Arguments to the contrary, particularly those of Officer and Darke, are shown to invalid.
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Donati I, Asaro F, Paoletti S. Experimental evidence of counterion affinity in alginates: the case of nongelling ion Mg2+. J Phys Chem B 2009; 113:12877-86. [PMID: 19736959 DOI: 10.1021/jp902912m] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The present contribution aims at testing experimentally the theoretical model previously devised (Donati, I.; Cesaro, A.; Paoletti, S.; Biomacromolecules 2006, 7, 281-287) for the description of the interaction between alginate and nongelling Mg(2+) ions. The model, based on an extension of the counterion condensation theory, introduces a contribution of free energy of affinity, DeltaG(aff,0), which depends on the monomer composition of the polyuronate. In the present work, three different alginates separately mimicking the mannuronan (polyM), the guluronan (polyG), and the polyalternating (polyMG) components of alginate, together with a natural alginate isolated from Laminaria hyperborea ( L. hyperborea ), were examined. They were treated with Mg(2+) ions, and relative variations in scattered light intensity, isothermal calorimetry (DeltaH(mix)), specific viscosity, and (23)Na NMR longitudinal relaxation rates were monitored with respect to samples at the same ionic strength but containing only Na(+) ions. The fraction of condensed magnesium counterions was found to be strongly dependent on alginate composition, increasing along the series mannuronan < polyalternating approximately L. hyperborea < guluronan, thus in good agreement with the theoretical predictions.
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Asaro F, Benedetti A, Savko N, Pellizer G. Inverse nonionic microemulsion studied by means of 1H, 13C, and PGSTE NMR during silica nanoparticle synthesis. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:3224-3231. [PMID: 19437786 DOI: 10.1021/la803826c] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The soluble species present in the reaction mixture that leads to silica nanoparticle production through the base catalyzed hydrolysis of tetraethyl orthosilicate (TEOS) and the successive condensation were investigated in situ, under the actual synthesis conditions, by means of 1H, 13C, and 29Si NMR spectroscopy. The two former nuclei, owing to higher sensitivity and their presence both in the reacting species and in the constituents of the W/O microemulsion (cyclohexane-igepal-CA-520-concentrated ammonia solution) afforded insight into the inverse microemulsion and allowed us to assess the kinetic rate of the hydrolysis step. It was verified that the microemulsion microstructure is maintained during the reaction. The characterization of the final nanoparticles was carried out by means of transmission electron microscopy (TEM). Special attention was paid to the reaction medium, and an extended assignment of the 1H and 13C resonances of the surfactant headgroup is reported together with the discussion of the changes they undergo due to the environmental modifications induced by transition from cyclohexane solution to W/O microemulsion and further to NH3 containing W/O microemulsion. The self-diffusion coefficient measurements revealed that NH3 exchanges among the inverse micelles diffusing through cyclohexane and confirmed that the preferred localization for ethanol, a byproduct of the reaction, is the bulk oil.
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Pellizer G, Asaro F. 14N NMR spectra of molecular nitrogen in SDS/pentanol swollen lamellar phases. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2008; 46 Suppl 1:S80-S85. [PMID: 18855343 DOI: 10.1002/mrc.2299] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
14N NMR spectra of air dissolved in lyotropic mesophases are reported. In order to observe the whole spectrum from a molecule in which the quadrupole coupling constant is on the order of a few megahertz, a weak alignment degree with respect to the magnetic field is mandatory. Therefore, dilute lyotropic liquid crystals, namely sodium dodecylsulphate (SDS)/pentanol swollen lamellar phases, were considered. The temperature dependence of the 14N quadrupolar splitting was followed both in the case of oil (either n-dodecane or n-heptane) and brine (a 0.2-M NaBr water solution) swelling. In the former, it paralleled the temperature dependence of the splittings of the alkane deuteria and, in both cases, it was opposite to 23Na quadrupolar splittings. Owing to the higher N2 solubility in hydrocarbons, the 14N NMR spectra provide complementary information to that obtained by means of the quadrupolar nuclei of water and hydrophilic solutes.
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Galasso V, Asaro F, Berti F, Pergolese B, Kovač B, Pichierri F. On the molecular and electronic structure of matrine-type alkaloids. Chem Phys 2006. [DOI: 10.1016/j.chemphys.2006.09.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Orioni B, Roversi M, La Mesa C, Asaro F, Pellizer G, D'Errico G. Polymorphic Behavior in Protein−Surfactant Mixtures: The Water−Bovine Serum Albumin−Sodium Taurodeoxycholate System. J Phys Chem B 2006; 110:12129-40. [PMID: 16800527 DOI: 10.1021/jp055950r] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Mixtures containing water, bovine serum albumin (BSA), and sodium taurodeoxycholate (NaTDC), a component of the bile in mammals, have been investigated in a wide range of composition and pH. Depending on the concentration of both solutes and the pH, solutions, precipitates, and gels are formed. Under spontaneous pH conditions, the transport properties in dilute solutions indicate the occurrence of significant interactions between BSA and the surfactant. Conversely, acidic media favor the formation of nonsoluble protein-surfactant complexes, with subsequent precipitation. The nucleation kinetics of the protein-surfactant complexes in solid form and the related precipitation processes can be slow or fast, depending on the overall solute content and the mole ratio. At high concentrations, a gel, extending on both sides of the charge neutralization line, and two-phase regions are observed. Gels shrink in open air and swell in the presence of excess water. Depending on concentration and temperature, the gels transform from an essentially liquidlike behavior to that peculiar to true gels (when G' > or = G''). The thermal gelation threshold, the temperature above which G' > or = G'', depends on BSA and NaTDC content and is concomitant to moderate heat effects, inferred by differential scanning calorimetry (DSC). The above data also indicate that the protein thermal denaturation in the gel is shifted to higher temperatures compared to water. Such a stabilizing effect is presumably related to the occurrence of both electrostatic and hydrophobic interactions with NaTDC. Water self-diffusion in the gels is slightly slower than that in the bulk and poorly sensitive to composition: it is about 65% the value of neat H2O in a wide concentration range, irrespective of the BSA, or NaTDC, concentration. A peculiar behavior is also observed in 23Na longitudinal and transverse relaxation rates. The T1 and T2 values, measured at 105.75 MHz on BSA-NaTDC gels, indicate that the motions determining the NMR relaxation of the sodium ions in the hydration layer of the protein-surfactant aggregates are not slow, having frequencies comparable with the Larmor one. The above properties, especially the rheological and the spectroscopic ones, are important for understanding the behavior of gels based on protein-surfactant mixtures.
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Galasso V, Asaro F, Berti F, Przybył A, Włodarczak J, Wysocka W, Habuš I, Kovač B. A combined spectroscopic and theoretical study of oxo- and thiono-sparteines. Chem Phys 2005. [DOI: 10.1016/j.chemphys.2005.01.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Pellizer G, Asaro F, Pergolese B. NMR investigations of Co(III) coordination compounds oriented in a dilute lyotropic liquid crystal. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2004; 42:756-759. [PMID: 15307057 DOI: 10.1002/mrc.1420] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A swollen lamellar phase, based on sodium dodecyl sulfate, pentanol and NaBr brine, was examined by means of NMR spectroscopy of isotopes with quadrupolar characteristics, namely 2H, 17O, 23Na and 81Br, present at natural abundance. Such a dilute lyotropic liquid crystal was capable of inducing a preferential orientation of the cobalt coordination compounds [Co(en)3]3+ and Co(acac)3, the 59Co NMR signals of which displayed quadrupolar splittings. Moreover, it imparted alignment in the magnetic field to the organocobaloxime [ClCD2Co(Hdmg)2H2O], as shown by the quadrupolar splitting of the deuterium of the axial ligand.
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Bernazzani L, Borsacchi S, Catalano D, Gianni P, Mollica V, Vitelli M, Asaro F, Feruglio L. On the Interaction of Sodium Dodecyl Sulfate with Oligomers of Poly(Ethylene Glycol) in Aqueous Solution. J Phys Chem B 2004. [DOI: 10.1021/jp049673k] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Galasso V, Asaro F, Berti F, Habuš I, Kovač B, De Risi C. Structural and spectroscopic characterization of oxo-sparteines. Chem Phys 2004. [DOI: 10.1016/j.chemphys.2004.03.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Dreos R, Tauzher G, Geremia S, Randaccio L, Asaro F, Pellizer G, Tavagnacco C, Costa G. An Unusual Reaction of Bis(dimethylglyoximato) Complexes: Synthesis and Characterization of Rhodium(III) Complexes Containing an Oxime-Imine Equatorial Moiety. Inorg Chem 2002. [DOI: 10.1021/ic00102a011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Seaborg GT, Asaro F. Isadore Perlman: April 12, 1915-August 3, 1991. BIOGRAPHICAL MEMOIRS. NATIONAL ACADEMY OF SCIENCES (U.S.) 2001; 75:265-87. [PMID: 11623761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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Asaro F, Lenarda M, Pellizer G, Storaro L. A multinuclear NMR study of [Pt0(PPh3)2(alkene)] compounds containing asymmetric olefins. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2000; 56A:2167-2175. [PMID: 11058062 DOI: 10.1016/s1386-1425(00)00278-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The 1H, 13C, 31P, and 195Pt NMR spectra of [Pt0(PPh3)2(eta-ABC(1) = C(2)XY)] compounds (ABC(1)= C(2)XY (1) A = B = X = Y = H; (3) A = B = X = H, Y = CN; (4) A = H, B = p-NO2-Ph, X = COOCH3, Y = CN; (5) A = H, B = Ph, X = COOCH3, Y = CN; (6) A = H, B = Ph, X = Y = CN; (7) A = H, B = OEt, X = Y = CN), where X and Y are electronacceptor substituents, and the 1H spectrum of [Pt0(PPh3)2(eta2-C60)] (2) are reported together with extended analyses and assignments, based also on the ring current effect of the olefin phenyl in (4-6). Deviations from first order in the 13C spectra allowed the determination of the relative signs of the coupling constants J(P(1), C) and J(P(2), C) of the alkene and of the triphenylphosphine carbons. Best fit simulation of the phosphine C ipso spectrum provided also the 13C isotopic shift on phosphorus for (1). These compounds are characterised by strong differences between the two platinum-phosphorus coupling constants in the case of asymmetric olefins (3-7). The chemical shifts of alkene C(1) and C(2) indicate notable polarisation of the olefin after complexation, while the 1J(Pt, C(1)) and 1J(Pt, C(2)) values are in agreement with a stronger interaction of Pt with C(1) than with C(2). These findings together with the trend of 195Pt chemical shifts confirm the important role played by back-donation in the bonding of platinum(0)-olefin compounds.
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Asaro F, Liguori L, Pellizer G. Exceptional Deshielding of (59)Co Caused by Deuteration of the Hydrogen Bonds in Cobaloximes This work was supported by MURST under the Project Cofin (MURST 97 CFSIB). Angew Chem Int Ed Engl 2000; 39:1932-1934. [PMID: 10940985 DOI: 10.1002/1521-3773(20000602)39:11<1932::aid-anie1932>3.0.co;2-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Asaro F, Liguori L, Pellizer G. Exceptional Deshielding of59Co Caused by Deuteration of the Hydrogen Bonds in Cobaloximes. Angew Chem Int Ed Engl 2000. [DOI: 10.1002/1521-3757(20000602)112:11<2008::aid-ange2008>3.0.co;2-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Asaro F, Dreos* R, Nardin G, Pellizer G, Peressini S, Randaccio* L, Siega P, Tauzher G, Tavagnacco C. para-Substituted diphenylborylated organocobaloximes: effects of substituents on conformation and redox properties. J Organomet Chem 2000. [DOI: 10.1016/s0022-328x(00)00043-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Asaro F, Gobetto R, Liguori L, Pellizer G. Solution 31P and 59Co and solid-state 31P CP/MAS NMR studies of triphenylphosphinecobaloximes. Chem Phys Lett 1999. [DOI: 10.1016/s0009-2614(98)01397-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Asaro F, Liguori L, Pellizer G. NMR parameters of cobalt and of the directly bonded organic carbons obtained from solution 59Co and 13C NMR spectra of cobaloximes. Phys Chem Chem Phys 1999. [DOI: 10.1039/a906376e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Asaro F, Camus A, Gobetto R, Olivieri AC, Pellizer G. 63Cu-31P coupling constants and 63Cu quadrupole couplings from 31P CP/MAS spectra of copper (I)--phosphine complexes with aryldithiocarboxylates or benzoate. SOLID STATE NUCLEAR MAGNETIC RESONANCE 1997; 8:81-88. [PMID: 9203282 DOI: 10.1016/s0926-2040(96)01289-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Magic-angle spinning 31P NMR spectra of solid [CuS2C-Ph(PPh3)2] 1, [{CuS2C-pT}4(PPh3)2] 2, [{CuS2C-Ph}4(PPh3)2] 3. [CuS2C-Ph(dppm)]2 4 and [CuO2C-Ph(dppm)]2 5, (T = tolyl, dppm = bis(diphenylphosphino)methane) were obtained at 109.6 MH2. They consist of distorted quartets from non-equivalent phosphorus atoms and provide approximate values of the indirect spin-spin coupling constant J[63Cu,31P], that are indicative of the covalency of the dithiocarboxylate-copper bonding. The spacing distortions are related to a number of molecular and structural parameters and thereby allow an estimation of the copper quadrupole coupling constant e2qQ/h which, as expected, is smaller for tetra-coordinated (1, 2, 3 and 4) than for tri-coordinated (5) copper sites. The spectrum of 2 has been successfully simulated (including the isotope effects from the less abundant 65Cu isotope) using the full theory for calculation of the spin eigenfunctions of the quadrupolar nucleus.
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Asaro F, Dreos R, Geremia S, Nardin G, Pellizer G, Randaccio L, Tauzher G, Vuano S. Synthesis, characterization and solution properties of organorhodium complexes derived from rhodoximes with one or two diphenylboron moieties in the oxime bridges. J Organomet Chem 1996. [DOI: 10.1016/s0022-328x(96)06479-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Asaro F, Costa G, Dreos R, Pellizer G, von Philipsborn W. Steric effects in organometallic compounds. A 103Rh NMR study of alkylrhodoximes. J Organomet Chem 1996. [DOI: 10.1016/0022-328x(95)06052-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Kubiak M, Głowiak T, Moszner M, Ziółkowski JJ, Asaro F, Costa G, Pellizer G, Tavagnacco C. Synthesis and characterization of a novel tetranuclear bimetallic complex containing rhodium(II) and zinc(II) as metal centres. Inorganica Chim Acta 1995. [DOI: 10.1016/0020-1693(95)04637-o] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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