| 1. |
|
|
| 2. |
- Bengtsson, Gösta, et al.
(författare)
-
The kinetics and mechanism of oxidation of hydroxylamine by iron(III)
- 2002
-
Ingår i: Journal of the Chemical Society. Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1472-7773 .- 1364-5447. ; :12, s. 2548-2552
-
Tidskriftsartikel (refereegranskat)abstract
- The kinetics of oxidation of hydroxylamine by iron() have been studied spectrophotometrically. The effects of pH, reactant and product concentrations led to two experimental rate expressions. The results obtained are consistent with a mechanism dependent on the relative iron(III)-to-hydroxylamine concentrations; an excess of iron() gives a stoichiometry of 2 : 1 for the total reaction and N2O as the oxidation product, whereas at equal amounts or excess of hydroxylamine the stoichiometry reduces to 1 : 1 with N-2 as the main product. In the latter case the rate expression d[ Fe(III)]/dt = k[Fe(III)](2) [NH2OH](2) /[Fe(III)](2) [H+](4) is obtained. The consistent mechanism identifies two pre-equilibria and the reaction of two different nitrogen-containing intermediates as the rate-determining step depending on the reactant ratios. The proposed mechanism does also involve the metal hydroxide complex Fe(OH)(2+), in agreement with previous results.
|
|
| 3. |
- Kopylovich, M. N., et al.
(författare)
-
Facile Ni(II)/ketoxime-mediated conversion of organonitriles into imidoylamidine ligands. Synthesis of imidoylamidines and acetyl amides
- 2003
-
Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 42:22, s. 7239-7248
-
Tidskriftsartikel (refereegranskat)abstract
- Treatment of alkyl nitriles with NiX2.6H(2)O (X = Cl, NO3) and 2-propanone oxime, followed by (X = Cl) addition of [i-Pr4N](NO3) for precipitation of the product, resulted in the formation of amidinium nitrates [RC(=NH2)NH2](NO3) (R = Me, Et, n-Pr), The reaction went to another direction with NiX2.2H(2)O, i.e., the reaction between neat RCN (R = Me, Et, n-Pr, i-Pr, n-Bu, CH2Cl, CH2C6H4OMe-p) and NiCl2.2H(2)O/2-propanone oxime (other ketoximes can also be used) gave the (imidoylamidine)Ni(II) complexes [Ni{(N) under bar (H)=C(R)NHC(R)=(N) under barH}(2)](2+) (1(2+)-7(2+)). The latter were isolated in good yields (65-91%) as the bis-chloride salts 1.Cl-2-6.Cl-2 and the mixed salt 7.(Cl)(p-MeOC6H4CH2CO2). Remarkably, the latter transformation does not proceed at all if NiCl2.2H(2)O or the ketoxime are taken alone. Liberation of imidoylamidines was performed for one alkyl-containing complex [2.Cl-2] and one benzyl-containing complex [7.(Cl)(p-MeOC6H4CH2CO2)], by (i) addition of HBF4.Et2O to the acetonitrile solution of the complexes to yield [N(H)=C(R)NHC(R)=NH].2HBF(4) (R = Et 8 and R = CH2C6H4OMe-p 9) or (ii) substitution for ethanediamine (en) with following precipitation of the complex [Ni(en)(3)]Cl-2 with formation of free N(H) C(R)NHC(R)=NH (R = Et 10 and R = CH2C6H4OMe-p 11). In contrast to the liberation in nonaqueous media, treatment of 2.Cl-2 and 7.(CI)(P-MeOC6H4CH2CO2) with Na(2)EDTA.2H(2)O in water-methanol solutions led to substitution and hydrolysis to furnish the acyl amides {EtC(=O)} 2NH (12) and {p-MeOC6H4CH2C(=0)}(2)NH (13). Alternatively, 12 and 13 were obtained by hydrolysis of 10 and 11 in water at pH ca. 8.5. It was shown that the oxime complexes trans-[NiCl2(C4H8C=NOH)(4)] (14) or cis-[Ni(O,O-NO3)(2)(C4H8C=NOH)(2)] (15) can be intermediates in the formation of amidines and imidoylamidines. The sequence of the Ni(II)/oxime mediated formation of (imidoylamidine)Ni complexes and liberation (or hydrolytic liberation) of the ligands opens up a novel, facile and environmentally benign route to imidoylamidines and acyl amides.
|
|
| 4. |
|
|
| 5. |
- Lyubimtsev, A. L., et al.
(författare)
-
The structure and bonding of Ni3Sn
- 2002
-
Ingår i: Journal of Alloys and Compounds. - 0925-8388 .- 1873-4669. ; 340:02-jan, s. 167-172
-
Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of Ni3Sn was calculated at ab initio levels for the crystal structure of the low-temperature modification of Ni3Sn refined upon data of single-crystal X-ray diffractometry (P6(3)/mmc, a=5.2950(7), c=4.247(1) Angstrom R=0.0288). The calculations were made with the use of fixed Gaussian (CRYSTAL98 software) and energy-dependent (Stuttgart TB-LMTO-ASA software) basis sets. Difference electron charge density maps were analysed and compared with that of a hypothetical hcp Ni in order to understand bonding in Ni3Sn. It was found that bonding in Ni3Sn has multicentre character with Ni-Sn interaction stronger than Ni-Ni one.
|
|
| 6. |
|
|
| 7. |
- Sabounchei, J. S., et al.
(författare)
-
Rhodium complexes containing O-bonded NHxMe2-xCHO (x=0, 1, 2) : X-ray structure of Rh(PPh3)(3)(OCHNHMe) CIO4
- 2001
-
Ingår i: Helvetica Chimica Acta. - 0018-019X .- 1522-2675. ; 84:10, s. 3075-3083
-
Tidskriftsartikel (refereegranskat)abstract
- Displacement of norbornadiene (nbd; bicyclo[2.2.1]hepta-2,5-diene) from [Rh(PPh3)(2)(nbd)]ClO4 by hydrogenation in the presence of PPh3 and formamide or Me-substituted derivatives, results in the formation of O-bonded formamide complexes [Rh(PPh3)(3)(OCHNHxMe2-x)]ClO4 (x=0, 1, 2) rather than N-bonded derivatives. These have been characterised by spectroscopic measurements and, in the case of [Rh(PPh3)(3)(OCHNHMe)]ClO4, by X-ray crystallography. All undergo oxidative addition with H-2, and the rates of ligand exchange in the Rh-I and Rh-III complexes have been determined by magnetisation-transfer measurements.
|
|
| 8. |
|
|
