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71.
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73.
Sixteen complexes of general formula R2SnL2 and R2(L)SnOSn(L)R2 (where L = N-acetyl-L-leucine or N-acetyl-L-phenylalanine) R = CH3, C2H5, n-C4H9, or n-C8H17) have been prepared by interaction between the ligand and R2SnO in 2:1 or 1:1 molar ratio. The complexes were characterized by IR, 1H NMR and 119Sn Mössbauer spectroscopy. All the 2:1 complexes are assigned six-coordinate, distorted octahedral geometry with chelating carboxylate groups, while the 1:1 complexes have oxygen-bridged binuclear five-coordinate, trigonal-bipyramidal configurations. The amido ?CO and ?NH groups are hydrogen bonded in the solid state. 相似文献
74.
75.
The behaviour of 2,1-benzisoxazoles (anthranils) towards electrophilic substitutions has been studied. Nitration of 5-chloro-2,1-benzisoxazole (VII) exclusively gives 4-nitro-5-chloro-2,1-benzisoxazole (XII). However, 5-chloro-3-phenyl-2,1-benzisoxazole (VIII) gives dinitrated products XIII, one nitro group entering at position C7 instead of C4 of the carbocyclic ring and the other at the 4′ position of the 3-aryl ring. When 6-nitro-3-carbalkoxy-2,1-benzisoxazoles (X and XI) are nitrated, 4-nitroisomers XV and XVI are obtained exclusively. The substituents already present in the carbocyclic ring exert decisive directing influence. While the parent 2,1-benzisoxazole (Ia) fails to react with dimethyl acetylenedicarboxylate, 6-nitro-2,1-benzisoxazole (XVII) and 5-chloro-2,1-benzisoxazole (VII) react to give 1,4-cycloadducts XIX and XX, respectively. These results suggest that 2,1-benzisoxazoles possess benzenoid as well as ortho-quinonoid character. 相似文献
76.
The stable complexes of amino acids with rare earths have found importance in the separation of these metals1. The complexation reactions of a number of dipeptides with copper and nickel have been reported in the literature2 – 9; but little work appears to have been done with rare earth metals. This paper is a continuation of our earlier communication10, and deals with the study of complexes of Gd3+, Dy3+, Er 3+ and Yb3+ with Glycyl-DL-valine. The Calvin—Bjerrum11, 12 pH titration technique, as modified by Irving and Rossotti13, has been employed. 相似文献
77.
Ligands, o-carboxyphenyldiphenylarsine, o-carboxyphenyldi(p-tolyl)arsine, o-carboxyphenyldiphenylarsine oxide and o-carboxyphenyldi(p-tolyl)arsine oxide react with beryllium(II) oxide acetate to form complexes of the general formula, [Be4 · O · (CH3COO)3(L)3] where LH is any of the aforementioned ligands. These have been found to be nonelectrolytes in nitrobenzene. Infrared spectral data suggest that arsenic(III or V) is not coordinated to the metal, while both the oxygens of acetate as well as carboxylate group are taking part in coordination, leaving the fundamental structure of beryllium oxide acetate intact. 相似文献
78.
1-N-Alkyl-1-azapenta-1,3-dienes 2 smoothly reacted with various mesoionic oxazolones 1 to afford 3,4-di-hydro-2-pyridones 3 in excellent yields and there was no evidence for the formation of any products arising from the cycloaddition on the carbon? carbon double bond or on the azomethine function. 相似文献
79.
Summary Platinum(IV)/platinum(II) chloride and bromide form 1 : 1, 1 : 2 or 3 : 2 (metal: ligand) addition compounds with 1,2-ethylene-, 1,3-propylene-and 1,4-butylene-bisdiphenyl-phosphine sulphide or selenide and 1,6-hexamethylene-bisdiphenylphosphine selenide. The adducts have been characterized by elemental analysis, i.r. and reflectance spectra, and molar conductance data. All adducts have been assigned bridged square planar or octahedral arrangements around platinum(II) or platinum(IV) ions respectively. Both oxidation states of platinum conform to class b behaviour with respect to the soft donor sulphur and selenium atoms of the ligands.Reprints of this article are not available. 相似文献
80.
3,5-Dihalo-2-aminobenzophenones 2 on prolonged reflux in dry pyridine gave 2,4,8,10-tetrahalo-6,12- diaryldibenzo[b,f][1,5]diazocines 3 in high yields. Attempted condensation of 2 with glycine ester hydrochloride under identical reaction conditions failed to afford 1,4-benzodiazepines. 相似文献