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91.
92.
A two-photon laser-induced fluorescence study on the transport of ground-state atomic hydrogen in a supersonic plasma jet, generated from an Ar-H (2) mixture, reveals an unexpected shock pattern. Whereas both the axial-velocity profile and the temperature profile of hydrogen atoms along the jet centerline can be interpreted in terms of a supersonic expansion of an Ar-H gas mixture, the H-atom density profiles do not satisfy the well established Rankine-Hugoniot relation leading to a nonconservation of the forward flux. The experimental results show that H atoms escape from the supersonic expansion by a diffusion process due to strong density gradients between the core of the jet and its vicinity.  相似文献   
93.
Compound cis,fac-[Mo(eta3-allyl)(CO)2(Hdmpz)3]BAr'4 (1) (Hdmpz = 3,5-dimethylpyrazole, Ar' = 3,5-bis(trifluoromethyl)phenyl) undergoes rapid substitution of one of the pyrazole ligands by anions, including the low nucleophilic ReO4-, a reaction that afforded [Mo(OReO3)(eta3-allyl)(CO)2(Hdmpz)2] (2), structurally characterized by X-ray diffraction. The new compounds fac-[Mn(CO)3(Hdmpz)3]BAr'4 (4a) and fac-[Mn(CO)3(HtBupz)3]BAr'4 (4b) (HtBupz = 3(5)-tert-butylpyrazole) also undergo pyrazole substitution with most anions, and the product from the reaction with nitrate was crystallographically characterized. Compounds 4a,b were found to be substitutionally stable toward perrhenate, and the adducts [Mn(CO)3(Hdmpz)3].[ReO4] (7a) and [Mn(CO)3(HtBupz)3].[ReO4].[Bu4N].[BAr'4] (7b), crystallographically characterized, display hydrogen bonds between one of the perrhenate oxygens and the N-H groups of two of the pyrazole ligands. The structurally similar adduct [Re(CO)3(Hdmpz)3].[ReO4] (8) was found to result from the interaction of [Re(CO)3(Hdmpz)3]BAr'4 with perrhenate. The reaction of [Re(OTf)(CO)5] with 3,5-dimethylpyrazole (Hdmpz) afforded [Re(CO)5(Hdmpz)]OTf (9). The reaction of 9 with Hdmpz and NaBAr'4 yielded [Re(CO)4(Hdmpz)2]BAr'4 (10), which was found to be unstable toward chloride anion. In contrast, the new compound fac,cis-[Re(CO)3(CNtBu)(Hdmpz)2]BAr'4 (11) is stable in solution in the presence of different anions. Binding constants for 11 with chloride, bromide, and nitrate are 1-2 orders of magnitude lower than those found for these anions and rhenium tris(pyrazole) hosts, indicating that the presence of the third pyrazole ligand is crucial. Compounds fac-[Re(CO)3(HPhpz)3]BAr'4 (14) (HPhpz = 3(5)-phenylpyrazole) and fac-[Re(CO)3(HIndz)3]BAr'4 (15) (HIndz = indazole) are, in terms of anion binding strength and selectivity, inferior to those with dimethylpyrazole or tert-butylpyrazole ligands.  相似文献   
94.
In the crystal networks of N,N′‐bis(2‐chlorobenzyl)‐N′′‐(2,6‐difluorobenzoyl)phosphoric triamide, C21H18Cl2F2N3O2P, (I), N‐(2,6‐difluorobenzoyl)‐N′,N′′‐bis(4‐methoxybenzyl)phosphoric triamide, C23H24F2N3O4P, (II), and N‐(2‐chloro‐2,2‐difluoroacetyl)‐N′,N′′‐bis(4‐methylphenyl)phosphoric triamide, C16H17ClF2N3O2P, (III), C=O...H—NC(O)NHP(O) and P=O...H—Namide hydrogen bonds are responsible for the aggregation of the molecules. This is the opposite result from that commonly observed for carbacylamidophosphates, which show a tendency for the phosphoryl group, rather than the carbonyl counterpart, to form hydrogen bonds with the NH group of the C(O)NHP(O) skeleton. This hydrogen‐bond pattern leads to cyclic R22(10) motifs in (I)–(III), different from those found for all previously reported compounds of the general formula RC(O)NHP(O)[NR1R2]2 with the syn orientation of P=O versus NH [R22(8)], and also from those commonly observed for RC(O)NHP(O)[NHR1]2 [a sequence of alternate R22(8) and R22(12) motifs]. In these cases, the R22(8) and R22(12) graph sets are formed through similar kinds of hydrogen bond, i.e. a pair of P=O...H—NC(O)NHP(O) hydrogen bonds for the former and two C=O...H—Namide hydrogen bonds for the latter. This article also reviews 102 similar structures deposited in the Cambridge Structural Database and with the International Union of Crystallography, with the aim of comparing hydrogen‐bond strengths in the above‐mentioned cyclic motifs. This analysis shows that the strongest N—H...O hydrogen bonds exist in the R22(8) rings of some molecules. The phosphoryl and carbonyl groups in each of compounds (I)–(III) are anti with respect to each other and the P atoms are in a tetrahedral coordination environment. In the crystal structures, adjacent molecules are linked via the above‐mentioned hydrogen bonds in a linear arrangement, parallel to [010] for (I) and (III) and parallel to [100] for (II). Formation of the NC(O)NHP(O)—H...O=C instead of the NC(O)NHP(O)—H...O=P hydrogen bond is reflected in the higher NC(O)NHP(O)—H vibrational frequencies for these molecules compared with previously reported analogous compounds.  相似文献   
95.
Varying coordination modes of the Schiff base ligand H2L [5-methyl-1-H-pyrazole-3-carboxylic acid (1-pyridin-2-yl-ethylidene)-hydrazide] towards different metal centers are reported with the syntheses and characterization of four mononuclear Mn(II), Co(II), Cd(II) and Zn(II) complexes, [Mn(H2L)(H2O)2](ClO4)2(MeOH) (1), [Co(H2L)(NCS)2] (2), [Cd(H2L)(H2O)2](ClO4)2 (3) and [Zn(H2L)(H2O)2](ClO4)2 (4), and a binuclear Cu(II) complex, [Cu2(L)2](ClO4)2 (5). In the complexes 1-4 the neutral ligand serves as a 3N,2O donor where the pyridine ring N, two azomethine N and two carbohydrazine oxygen atoms are coordinatively active, leaving the pyrazole-N atoms inactive. In the case of complex 5, each ligand molecule behaves as a 4N,O donor utilizing the pyridine N, one azomethine N, the nitrogen atom proximal to the azomethine of the remaining pendant arm and one pyrazole-N atom to one metal center and the carbohydrazide oxygen atom to the second metal center. The complexes 1-4 are pentagonal bipyramidal in geometry. In each case, the ligand molecule spans the equatorial plane while the apical positions are occupied by water molecules in 1, 3 and 4 and two N bonded thiocyanate ions in 2. In complex 5, the two Cu(II) centers have almost square pyramidal geometry (τ = 0.05 for Cu1 and 0.013 for Cu2). Four N atoms from a ligand molecule form the basal plane and the carbohydrazide oxygen atom of a second ligand molecule sits in the apex of the square pyramid. All the complexes have been X-ray crystallographically characterized. The Zn(II) and Cd(II) complexes show considerable fluorescence emission while the remaining complexes and the ligand molecule are fluorescent silent.  相似文献   
96.
97.
Seven E[Cu(OR)2] copper(I) complexes (E=K+, {K(18C6)}+ (18C6=[18]crown‐6), or Ph4P+; R=C4F9, CPhMeF2, and CMeMeF2) have been prepared and their reactivity with O2 studied. The K[Cu(OR)2] species react with O2 in a copper‐concentration‐dependent manner such that 2:1 and 3:1 Cu/O2 adducts are observed manometrically at ?78 °C. Analogous reactivity with O2 is not observed with the {K(18C6)}+ or Ph4P+ derivatives. Solution conductivity data demonstrate that these K[Cu(OR)2] complexes do not behave as 1:1 electrolytes in solution. The K+ ions induce aggregation of multiple [Cu(OR)2]? units through K???F/O interactions and thereby effect irreversible O2 reduction by multiple Cu centers. Bond valence analyses for the potassium cations confirm the dominance of the fluorine interactions in the coordination spheres of K+ ions. Intramolecular hydroxylation of ligand aryl and alkyl C? H bonds is observed. Nucleophilic reactivity with CO2 is observed for the oxygenated Cu complexes and a CuII carbonate has been isolated and characterized.  相似文献   
98.
The structures of four halogenated N,2‐diarylacetamides are reported and compared with a range of analogues. N‐(4‐Chloro‐3‐methylphenyl)‐2‐phenylacetamide, C15H14ClNO, (I), and N‐(4‐bromo‐3‐methylphenyl)‐2‐phenylacetamide, C15H14BrNO, (II), are isostructural in the space group P. The molecules of (I) and (II) are linked into chains of rings by a combination of N—H...O and C—H...π(arene) hydrogen bonds. The molecules of N‐(4‐chloro‐3‐methylphenyl)‐2‐(2,4‐dichlorophenyl)acetamide, C15H12Cl3NO, (III), and N‐(4‐bromo‐3‐methylphenyl)‐2‐(2‐chlorophenyl)acetamide, C15H13BrClNO, (IV), are linked into simple C(4) chains by N—H...O hydrogen bonds, but significant C—H...π(arene) interactions are absent. The N‐aryl groups in compounds (III) and (IV) adopt a different orientation, by ca 180°, from that of the corresponding groups in compounds (I) and (II), but otherwise the conformations of (I)–(IV) are very similar. Comparisons are drawn between compounds (I) and (IV) and a range of analogues of the type R1CH2CONHR2, where R2 represents a halogenated aryl ring and R1 represents either another halogenated aryl ring or a naphthalen‐1‐yl unit.  相似文献   
99.
Reactions of copper(II) acetate with N1‐subsitituted salicylaldehyde thiosemicarbazones [R1R2C2=N3–N2H–C1(=S)–N1HR3;R1 = 2‐HO–C6H4–, R2 = H : R3 = Me (H2L1), Et (H2L2)] are described. Copper(II) acetate was reacted with H2L1 and H2L2 ligands in the presence of polypyridyl co‐ligands, and this led to the formation ofmononuclear complexes, [Cu(κ3‐O, N, S‐L1)(κ2‐N, N‐bipy)] ( 1 ),[Cu(κ3‐O, N, S‐L)(κ2‐N, N‐phen)] [L = L1 ( 3 ), L2 ( 4 )], [Cu(κ3‐O, N, S‐L)(κ2‐N, N‐tmphen)] [L =L1 ( 5 ), L2 ( 6 )] and a dinuclear complex, [Cu2L22(bipy)] ( 2 ) (bipy = 2, 2′‐bipyridine, phen = 1, 10‐phenanthroline, tmphen = 3, 4, 7, 8‐tetramethyl‐1, 10‐phenanthroline). In dinuclear complex 2 , one ligand is O, N3,S‐chelating, while second is O, N3,S‐chelation‐cum‐N2‐bridging; and in all others thio‐ligands are O, N3,S‐chelating. The μeff values for the complexes lie in the range of 1.79–1.83 BM. Complexes 1 , 3 – 6 have square pyramidal arrangement, whereas complex 2 has two independent molecules in the crystal lattice, and each molecule has trigonal bipyramidal square planar (5:4) coordination pair. Complexes 2 , 4 , and 6 showed fluorescence properties.  相似文献   
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