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71.
Summary The preparation and properties of cationic arenerhodium(I) complexes of general formula [Rh {P(OMe)3}(6-arene)]A [arene=C6H6–nMen (n=0, 1, 2, 3, 4 or 6); A=ClO
6
–
, PF
6
–
] are described. The coordinated arene is dissociated in (CD3)2 CO or DCCl3 solution and this dissociation decreases with increased methyl substitution of the arene ligand.The ability of these cationic complexes to function as an intermediate for the synthesis of other rhodium(I) complexes by displacement of the coordinated arene with or -donor ligands has been studied. 相似文献
72.
Guillaume Bernis Kaouther Salhi Simone Scotti 《Mathematics and Financial Economics》2018,12(4):541-559
This paper deals with a model for pricing Collateralized Loan Obligations, where the underlying credit risk is driven by a marked Hawkes process, involving both clustering effects on defaults and random recovery rates. We provide a sensitivity analysis of the CLO price with respect to the parameters of the Hawkes process using a change of probability and a variational approach. We also provide a simplified version of the model where the intensity of the Hawkes process is taken as the instantaneous default rate. In this setting, we give a moment-based formula for the expected survival probability. 相似文献
73.
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75.
Mauricio Valderrama Mario Scotti Pedro Cifuentes Ricardo Ganz 《Transition Metal Chemistry》1984,9(8):312-314
Summary The preparation and properties of cationic arenerhodium(I) complexes of general formula [Rh(diolefin)(6arene)]ClO4 (diolefin=1,5-cyclooctadiene, tetrafluorobenzobarrelene or trimethyltetrafluorobenzobarrelene; arene = biphenyl or diphenylmethane) are described. These complexes react with the solvated intermediate complex [Rh(diolefin)(Me2CO)x]ClO4 to give homobimetallic [(diolefin)Rh(Ph2CH2)Rh(diolefin)](ClO4)2 derivatives. New heterobimetallic complexes of the type [(diolefin)Rh(Ph2CH2)Cr(CO)3]ClO4 have been synthesized by reaction of Cr(CO)3(6-Ph2CH2) with the solvated complex [Rh(diolefin)(Me2CO)x]ClO4 or, alternatively by treatment of [Rh(diolefin)(6-arene)]ClO4 with the complex Cr(CO)3(6Me3B3N3Me3) in chloroform solution. 相似文献
76.
Canevali C Mattoni M Morazzoni F Scotti R Casu M Musinu A Krsmanovic R Polizzi S Speghini A Bettinelli M 《Journal of the American Chemical Society》2005,127(42):14681-14691
Ce-doped borosilicate (BSG), phosphosilicate (PSG), and borophosphosilicate (BPSG) glasses (B:P:Si molar ratios 8:0:92, 0:8:92, and 8:8:84; Ce:Si molar ratio 1 x 10(-)(4) to 1 x 10(-)(2)) were prepared by the sol-gel method. High-resolution transmission electron microscopy (HRTEM), (31)P, (29)Si, and (11)B magic angle spinning nuclear magnetic resonance (MAS NMR), electron paramagnetic resonance (EPR), and UV-vis absorption investigations demonstrated that, in PSG and BPSG, Ce(3+) ions interact with phosphoryl, [O=PO(3/2)], metaphosphate, [O=PO(2/ 2)O](-), and pyrophosphate, [O=PO(1/2)O(2)](2)(-), groups, linked to a silica network. This inhibits both CeO(2) segregation and oxidation of isolated Ce(3+) ions to Ce(4+), up to Ce:Si = 5 x 10(-)(3). In BSG, neither trigonal [BO(3/2)] nor tetrahedral [BO(4/2)](-) boron units coordinate cerium; thus, Ce(3+) oxidation occurs even at Ce:Si = 1 x 10(-)(4), as in pure silica glass (SG). The homogeneous rare-earth dispersion in the host matrix and the stabilization of the Ce(3+) oxidation state enhanced the intensity of the photoluminescence emission in PSG and BPSG with respect to BSG and SG. The energy of the Ce(3+) emission band in PSG and BPSG matrixes agrees with the phosphate environment of the rare earth. 相似文献
77.
Complexes of the type [(C5H5)Co{P(O)R2}3]?, R = OCH3, OC2H5, react as tridentate oxygen ligands L? with [MBr(CO)5], M = Mn, Re, in hexane or tetrahydrofuran to give the tricarbonyl derivatives [LM(CO)3]. The slightly volatile yellow crystalline compounds have been characterized by elemental analysis, 1H NMR, IR and mass spectra. The low CO stretching frequencies indicate that the ligands L? are good π-donor ligands. 相似文献
78.
79.
Comparison between CP/MAS 13C-NMR and pyrolysis-GC/MS in the structural characterization of humins and humic acids of soil and sediments 总被引:2,自引:0,他引:2
D. Fabbri M. Mongardi L. Montanari G. C. Galletti G. Chiavari R. Scotti 《Analytical and bioanalytical chemistry》1998,362(3):299-306
The chemical structure of humins (HUs) and humic acids (HAs) of terrestrial and marine environments was investigated by cross-polarization
magic angle spinning 13C-nuclear magnetic resonance spectroscopy (CP/ MAS 13C-NMR) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Samples of HUs and HAs were obtained from sediments
of the Adriatic Sea, the Lagoon of Ravenna (Adriatic Sea) and the Bubano Lake as well as from an agricultural soil. HUs displayed
pyrograms and NMR spectra different from those of related HAs. According to NMR spectra HUs were more aliphatic and contained
fewer carboxyl groups than HAs, while pyrolysates of HUs were characterized by higher levels of products arising from carbohydrates
and lower levels of lignin methoxyphenols with respect to HAs. The relative content of paraffinic carbons determined by NMR
was in good agreement with the relative abundance of unbranched aliphatic hydrocarbons released by pyrolysis. Both techniques
evidenced the importance of polymethylene structures in HUs.
Received: 5 January 1998 / Revised: 24 March 1998 / Accepted: 25 March 1998 相似文献
80.