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1.
Reaction of the activated mixture of Re 2(CO) 10, Me 3NO and MeOH with a 1:1 mixture of rac ( d/ l)- and meso-1,1,4,7,10,10-hexaphenyl-1,4,7,10-tetraphosphadecane (hptpd) yields a mixture of ( d/ l)- and meso-[{Re 2(μ-OMe) 2(CO) 6} 2(μ,μ′-hptpd)] 1. The diastereomers can be easily separated by selective dissolution of d/ l-1 in benzene, and give clearly distinguishable 1H- and 31P-NMR spectra. The fluxional behavior of d/ l-1 in solution has been studied by variable-temperature 1H- and 31P-{ 1H}-NMR spectroscopy. The crystal structures of both d/ l- and meso-1 have been determined. Both molecules consist of two {Re 2(μ-OMe) 2(CO) 6} moieties which are bridged by the two P---CH 2---CH 2---P moieties of the hptpd ligand. Whilst the molecules of meso-1 possess crystallographic i-symmetry, those of d/ l-1 do not have any crystallographic symmetry. These diastereomers therefore give clearly distinguishable Raman spectra in the solid state. Reaction of tris[2-(diphenylphosphino)ethyl]phosphine (tdppep) with the activated mixture affords the complex [{Re 2(μ-OMe) 2(CO) 6}(μ,η 2-tdppep)] 2, and the analogous reaction involving bis[2-diphenylphospinoethyl)phenylphosphine (triphos) gives [{Re 2(μ-OMe) 2(CO) 6}(μ,μ′,η 3-triphos){Re 2(CO) 9}] 3 and [{Re 2(μ-OMe) 2(CO) 6}(μ,η 2-triphos)] 4. 相似文献
2.
The reaction of methylzirconocenechloride with 2-bornenyllithium yields (2-bornenyl)methylzirconocene (10a). Carbonylation of 10a takes place exclusively by CO-insertion into the Zr-C(sp 2) bond to give Cp 2ZrMe(η 2-OC-C 10H 15) (16a). The corresponding hafnium complex 10b reacts analogously to give 16b. Complex 16a was characterized by X-ray diffraction, and found to contain an η 2-acyl ligand bonded to zirconium in the thermodynamically favored “O-inside” arrangement with the following bonding parameters: d Zr-C(acyl) = 2.192(7) Å, d Zr-O(acyl) = 2.258(6) Å, d C=O = 1.246(9) Å, angles O(acyl)---Zr---C(acyl) = 32.5(2)°, Zr---C(acyl)---O(acyl) = 76.7(4)°. 相似文献
3.
The nucleophilicity of the bridging atom of the selenium complex (μ-Se)[(η 5-C 5H 5)Fe(CO) 2] 2 (1) has been demonstrated by addition of the complex cation [(η 5-C 5H 5)Fe(CO) 2] +: Reaction of 1 with the ionic complex [(η 5-C 5H 5)Fe(CO) 2-(THF)][BF 4] cleanly yields the ionic trinuclear complex [(μ 3-Se)(η 5-C 5H 5)-Fe(CO) 23][BF 4] (3). This addition reaction converts the bridging selenium atom from a bent FeSeFe structure into a flattened Fe 3Se pyramid (X-ray diffraction studies), without significant changes in the iron-selenium bond lengths (244.9(<1) pm and 242.7(1)/243.3(1)/244.8(1) pm, respectively). These bonds are considered to be single bonds in accord with the EAN rule. 相似文献
4.
UV irradiation of tricarbonyl-η 5-2,4-dimethyl-2,4-pentadien-1-yl-manganese (2) in THF at 208 K yields solvent-stabilized dicarbonyl-η 5-2,4-dimethyl-2,4-pentadien-1-yl-tetrahydrofurane-manganese (3), which reacts in situ with two equivalents of 1-dimethylamino-2-propyne (4) to dicarbonyl-1–5-η-2,4-dimethyl-(6-dimethylaminomethyl- N)-10-dimethylamino-deca-2,4,6,8- tetraen-1-yl-manganese (5). The crystal and molecular structure was determined by an X-ray diffraction analysis. Complex 5 crystallizes in the monoclinic space group P2 1/ c, A = 1109.9(2) pm, B = 836.0(2) pm, C = 2156.9(4) pm, β = 93.23(3)°, V = 1.9982(7) nm 3, Z = 4. Complex 5 was also studied in solution by IR and NMR spectroscopy. A possible formation mechanism of 5 will be discussed. ZusammenfassungUV-Bestrahlung von Tricarbonyl-η5-2,4-dimethyl-2,4-pentadien-1-yl-mangan (2) in THF bei 208 K liefert solvenstabilisiertes Dicarbonyl-η5-2,4-dimethyl-2, 4-pentadien-1-yl-tetrahydrofuran-mangan (3), welches in situ mit zwei Äquivalenten 1-Dimethylamino-2-propin (4) zu Dicarbonyl-1–5-η-2,4-dimethyl-(6-dimethylaminomethyl-N)-10-dimethylamino-deca-2,4,6,8-tetraen-1-yl-mangan (5) reagiert. Seine Kristall- und Molekülstruktur wurde durch eine Röntgenbeugungsanalye bestimmt. Komplex 5 kristallisiert in der monoclinen Raumgruppe P21/c, A = 1109.9(2) pm, B = 836.0(2) pm, C = 2156.9(4) pm, β = 93.23(3)°, V = 1.9982(7)_ nm3, Z = 4. Komplex 5 wurde auch in Lösung IR- und NMR-spektroskopisch untersucht. Ein möglicher Bildungsmechanismus von 5 wird diskutiert. 相似文献
5.
Upon UV irradiation in hexane at 243 K tricarbonyl-η 5-cyclohexadienyl-manganese (1) and two equivalents of 2-butyne (2) or diphenylacetylene (4) yield in successive [5 + 2, 3 + 2] cycloadditions tricarbonyl-η 2:2:1-1,2,3,10-tetramethyl-tricyclo[5.2.1.0 4,9]-deca-2,5-dien-10-yl-manganese (6), or tricarbonyl-η 2:2:1-1,2,3,10-tetraphenyl-tricyclo[5.2.1.0 4,9]-deca-2,5-dien-10-yl-manganese (8), respectively. 3-Hexyne (3) reacts with 1 under the same conditions by successive [5 + 2, 3 + 2] cycloadditions and 1,4-H-shift to tricarbonyl-η 2:2:1-1,2,3-triethyl-10-ethylidene-tricyclo[5.2.1.0 4,9]dec-2-en-5-yl-manganse (7). Identical products are also obtained when 1 is first irradiated in THF at 208 K and the thermolabile intermediate, dicarbonyl-η 5-cyclohexadienyl-tetrahydrofurane-manganese (11), is treated with an excess of the alkynes 2–4. In contrast, bis(trimethylsily)acetylene (5) substitutes photochemically in 1 only a CO ligand to yield dicarbonyl-η 5-cyclohexadienyl-η 2-bis(trimethylsily)Acetylene-manganese (9). The crystal and molecular structure of 7 was determined by an X-ray diffraction analysis. Complex 7 crystallizes in the triclinic space group
, a = 822.6(2) pm, B = 882.5(2) pm, C = 1344.6(2) pm, = 92.36(2)°, β = 107.13(2)°, γ = 99.71(2)°, V = 0.9152(3) nm 3, Z = 2. The complexes 6–9 were studied in solution by IR and NMR spectroscopy. The structures of 6,8 and 9 were elucidated from the NMR spectra. A possible formation mechanism for the complexes 6–9 will be discussed. 相似文献
6.
The gallium(I)tris(trimethylsilyl)silyl compound {GaSi(SiMe 3) 3} 4 (1) is obtained by reaction of Ga 2Cl 4-2dioxane with LiSi(SiMe 3) 3-3THF. The crystal structure of 1 reveals a tetramer with a nearly regular tetrahedral framework of gallium atoms. The gallium-gallium distances average 258.4 pm. Ab initio calculations on various substituted gallium tetrahedrons showed a greater stability of silyl-substituted cages compared with organyl substituted ones. Crystal data, with Mo K radiation are as follows: {GaSi(SiMe 3) 3} 4 · Si(SiMe 3) 4 (1), a, B = 1923.3(3) pm, C = 2671.2(4) pm, V = 9.881(3) nm 3; tetragonal space group P4/ ncc; Z = 4; 1513 ( I > 2σ( I)) data; RI = 0.068. ZusammenfassungDas Gallium(I)tris(trimethylsilyl)silyl-Derivat {GaSi(SiMe3)3}4 (1) wird durch Umsetzung von Ga2Cl4-2Dioxan mit LiSi(SiMe3)3-3THF erhalten. Die Analyse der Kristallstruktur zeigt ein Tetramer mit einem nahezu regulären Gallium-Tetraeder-Gerüst. Der Mittelwert der Gallium-Gallium-Abstände betrügt 258.4 pm. Ab initio-Berechnungen verschiedener Gallium(I)-Verbindungen belegten eine erhöhte Stabilität von silyl-substituierten Clustern im Vergleich zu organyl-substituierten. Kristalldaten, mit Mo K -Strahlung; {GaSi(SiMe3)3 }4 · Si(SiMe3)4 (1), a, B = 1923.3(3) pm, C = 2671.2(4) pm, V = 9.881(3) nm3; tetragonal, Raumgruppe P4/ncc; Z = 4; 1513 (I > 2 σ(I)) Daten; RI = 0.068. 相似文献
7.
When thienyl Schiff base 1, derived from 2-formylthiophene and hydrazine, reacted with Fe 2(CO) 9 in n-hexane, three major complexes were obtained: (1) a diironhexacarbonyl complex with two 2-thienylmethylideneamido bridging ligands 2, which resulted from the =N---N= bond cleavage of ligand 1; (2) a doubly cyclometalated di-μ-di-(η 1:η 2-thienyl; η 1:η 1( N))bis(hexacarbonyldiiron) complex (3); and (3) a cyclometalated (μ-η 1:η 2-thienyl; η 1:η 1( N))hexacarbonyldiiron complex (4). Molecular structures of compounds 1a, 1c, and 2a have been determined by single-crystal X-ray diffraction. 相似文献
8.
Methyl(oxo)bis(η 2-peroxo)rhenium(VII)1, the active species of the system CH 3ReO 3/H 2O 2 in the catalytic oxidation of different organic and organometallic compounds, is stabilized by a water molecule attached to the rhenium center. This water molecule can be removed and substituted by hexamethylphosphoramide (HMPA) to yield (hexamethylphosphoramide)methyl(oxo)bis(η 2-peroxo rhenium(VII) (3). The synthesis, crystal structure (X-ray difraction study), and catalytic properties of which compound are reported. Crystal data are as follows: monoclinic, space group P2 1/ n, A = 900.76(7) pm, B = 1229.80(11) pm, C = 1318.57(11) pm, β = 90.251(7)°, Rw = 0.034 for 1878 reflections. The catalytic properties of compound 3 in the oxidation of olefins with H 2O 2 are similar to those of 1. 相似文献
9.
The silyl group migration observed upon treating ( R)(+)-(η 5-C 5H 5)Fe(CO) 2-SiMePh(1-Np) with n-BuLi occurs with retention of configuration at silicon. The anion resulting from the migration, (η 5-C 5H 4SiMePh(1-Np))Fe(CO) 2Li, is alkylated with MeI to give ( R)-(−)-(η 5-C 5H 4SiMePh(1-Np))Fe(CO) 2Me (II). Compound II is independently prepared from (η 5-C 5H 5)Fe(CO) 2Me. A concerted mechanism for the migration involving frontside nucleophilic attack at silicon is suggested. 相似文献
10.
The interaction between Mo 2(O 2CCH 3) 4, Me 3SiI and I 2 in THF resulted in oxygen abstraction from the solvent and formation of [Mo 2(μ-O)(μ-I)(μ-O 2CCH 3) I 2(THF) 4] +[MoOI 4(THF)] − and I---(CH 2) 4---I. The molybdenum complex has been characterized by X-ray diffractometry. Crystal data: triclinic, space group P
, a = 13.827(3) Å; b = 15.803(7) Å; c = 9.950(3) Å; = 93.34(4)°; β = 102.40(2)°; γ = 90.09(2)°; V = 2120(2) Å 3; Z = 2; dcalc = 2.559 g cm −3; R = 0.0476 ( Rw = 0.0613) for 370 parameters and 3938 data with F02> 3σ( F02). The metal-metal distance in the cation is 2.527(2) Å and indicates a strong interaction. The magnetic behavior is consistent with the assignment of one unpaired electron to the Mo 27+ core of the cation and one to the d1 Mo(V) center of the anion. The interaction between Mo(CO) 6 and I 2 in THF also results in the formation of 1,4-diiodobutane. 相似文献
11.
The complex [MoW(μ-CC 6H 4Me-4)(CO) 2(η 7-C 7H 7)(η 5-C 2B 9H 10Me)] reacts with diazomethane in Et 2O containing EtOH to afford the dimetal compound [MoW(OEt)(μ-CH 2){μ-C(C 6H 4Me-4)C(Me)O}(η 7-C 7H 7)(η 5-C 2B 9H 10Me)]. The structure of this product was established by X-ray diffraction. The Mo---W bond [2.778(4) Å] is bridged by a CH 2 group [μ-C---Mo 2.14(3), μ-C---W 2.02(3) Å] and by a C(C 6H 4Me-4)C(Me)O fragment [Mo---O 2.11(3), W---O 2.18(2), Mo---C(C 6H 4Me-4) 2.41(3), W---C(C 6H 4Me-4) 2.09(3), Mo---C(Me) 2.26(3) Å]. The molybdenum atom is η 7-coordinated by the C 7H 7 ring and the tungsten atom is η 5-coordinated by the open pentagonal face of the nido-icosahedral C 2B 9H 10Me cage. The tungsten atom also carries a terminally bound OEt group [W---O 1.88(3) Å]. The 1H and 13C-{ 1H} NMR data for the dimetal compound are reported and discussed. 相似文献
12.
The following structural peculiarities of the agostic acyl structure
2R) (R = H, SiMe 3) and some characteristic chemical reactivity of the M-η 2-acyl and iminoacyl linkage are described. (i) A structural comparison of the bonding parameters within three agostic acetyl Mo complexes containing the dithioacid ligand, indicates that the agostic interaction strengthens upon increasing the electron-releasing properties of the S-chelating ligand. (ii) The acyl-xanthate complex Mo(C(O)Me)(S 2COR)(CO)(PMe 3) 2 undergoes loss of a sulfur atom from the coordinated xanthate and coupling with the acyl ligand to form complexes containing coordinated alkoxythiocarbonyl and monothioacetate ligands. The latter can be metathetically replaced by KS 2COR. (iii) Upon heating at 70°C η 2-acyl-dicarbonyl bispirazolilborate complexes of molybdenum of the type Mo(H 2B(pz *) 2)(η 2-C(O)Me)(CO) 2(PMe 3) (pz * = 3,5-dimethyl-pyrazol-1-yl) yield functionalized acyl ligands derived from the stereo- and regioselective intramolecular addition of one of the B---H bonds of the H 2B(pz *) 2 group across the C=O moiety of the η 2-acyl group. (iv) The η 2-acyl-isocyanide complexes {Mo}(η 2-C(O)R)(CNR′) ({Mo} = Mo(H 2B(pz *) 2)(CO)(PMe 3)) undergo irreversible thermal isomerization to the corresponding η 2-iminoacyl-carbonyl derivatives {MO}(η 2-C(NR′)R)(CO). This isomerization reaction follows first-order kinetics. 相似文献
13.
The synthesis and reactivity of {(η 5-C 5H 4SiMe 3) 2Ti(CCSiMe 3) 2} MCl 2 (M = Fe: 3a; M = Co: 3b; M = Ni: 3c) is described. The complexes 3 are accessible by the reaction of (η 5-C 5H 4SiMe 3) 2Ti(CSiMe 3) 2 (1) with equimolar amounts of MCl 2 (2) (M = Fe, Co, Ni). 3a reacts with the organic chelat ligands 2,2′-dipyridyl (dipy) (4a) or 1,10-phenanthroline (phen) (4b) in THF at 25°C to afford in quantitative yields (η 5-C 5H 4SiMe 3) 2Ti(CSiMe 3) 2 (1) and [Fe(dipy) 2]Cl 2 (5a) or [Fe(phen) 2]Cl 2 (5b). 1/ n[Cu IHal] n (6) or 1/ n[Ag IHal] n (7) (Hal = Cl, Br) react with {(η 5 -C 5H 4SiMe 3) 2Ti(CCSiMe 3) 2}FeCl 2 (3a), by replacement of the FeCl 2 building block in 3a, to yield the compounds {(η 5-C 5H 4SiMe 3) 2Ti(C CSiMe 3) 2}Cu IHal (8) or {(η 5-C 5H 4SiMe 3) 2Ti(CSiMe 3) 2}Ag IHal (9) (Hal = Cl, Br), respectively. In 8 and 9 each of the two Me 3SiCC-units is η 2-coordinated to monomeric Cu I Hal or Ag IHal moieties. Compounds 8 and 9 can also be synthesized by the reaction of (η 5-C 5H 4SiMe 3) 2 Ti(CSiMe 3) 2 (1) with 1/ n[Cu IHal] n (6) or 1/ n [Ag IHal] n (7) in excellent yields. All new compounds have been characterized by analytical and spectroscopic data (IR, 1H-NMR, MS). The magnetic moments of compounds 3 were measured. 相似文献
14.
Samples of liquid crystalline poly(γ-benzyl-glutamate) solutions are sheared between glass surfaces with gaps, d = 10-500 μ, and shearing velocities, V = 0·05-10 000 μs -1 so that the Ericksen number E ≡ Vdγ1/ K is varied over a large range, E ≈ 1-10 7. Here γ 1 is the rotational viscosity and K1 is the Frank splay constant, with γ 1/ K1 estimated to be approximately 1 s μ -2 for our samples. We observe by polarizing microscopy a sequence of transitions with increasing Ericksen number analogous to that observed in small molecule tumbling nematics: namely rotation of the director out of the shearing plane and into the vorticity direction at Vd ≈ 25 μ 2 s -1, and formation of roll cells at Vd ≈ 50 μ 2 s -1. The roll cells become finer with increased Vd in accord with predictions of linear stability theory using the Leslie-Ericksen equations, and at Vd ≳ 500 μ 2 s -1, the cells become very irregular, producing director turbulence. The turbulence becomes finer in scale as Vd increases, reaching sub-micron, and possibly molecular scales when Vd ≧ 10 5 μ 2 s -1. At the highest velocities, transitions in orientation and texture are controlled by the Deborah number De≡λ V/d, where λ is the molecular relaxation time, and uniform texture-free samples are obtained when De ≳ 5. 相似文献
15.
The complex Fe(η 6-C 5H 5CMe 3) 2 crystallizes in the centrosymmetric triclinic space group P
( Ci1; No. 2) with unit cell dimensions of a 8.770(1) Å, b 8.878(1) Å, c 11.991(1) Å, 107.56(1)°, β 90.85(1)°, γ 90.13(1)°, V 890.0(2) Å 3 and Z = 2. A full sphere of data was collected on a four-circle diffractometer. The structure was solved and refined to R 7.93% for all 3155 independent reflections and R 4.98% for those 2002 data with | F0 | > 6σ. | F0 |. The molecules lie on crystallographic inversion centers at 0, 0, 0 and 1/2, 0, 1/2; the crystallographic asymmetric unit therefore consists of two independent half molecules. The molecule centered at 0, 0, 0 (molecule “A”) is ordered and well-defined; that centered on 1/2, 0, 1/2 (molecule “B”)is probably disordered, as indicated by larger “thermal parameters” and a greater range of apparent interatomic distances. Discussion em phasizes the geometry of molecule A, which has precise Ci symmetry with Fe(1A)-B(1A) 2.297(4) Å and Fe(1A)-C(ring) distances ranging from 2.057(6) Å to 2.138(4) Å. 相似文献
16.
The reactions of the diruthenium carbonyl complexes [Ru 2(μ-dppm) 2(CO) 4(μ,η 2-O 2CMe)]X (X=BF 4− (1a) or PF 6− (1b)) with neutral or anionic bidentate ligands (L,L) afford a series of the diruthenium bridging carbonyl complexes [Ru 2(μ-dppm) 2(μ-CO) 2(η 2-(L,L)) 2]X n ((L,L)=acetate (O 2CMe), 2,2′-bipyridine (bpy), acetylacetonate (acac), 8-quinolinolate (quin); n=0, 1, 2). Apparently with coordination of the bidentate ligands, the bound acetate ligand of [Ru 2(μ-dppm) 2(CO) 4(μ,η 2-O 2CMe)] + either migrates within the same complex or into a different one, or is simply replaced. The reaction of [Ru 2(μ-dppm) 2(CO) 4(μ,η 2-O 2CMe)] + (1) with 2,2′-bipyridine produces [Ru 2(μ-dppm) 2(μ-CO) 2(η 2-O 2CMe) 2] (2), [Ru 2(μ-dppm) 2(μ-CO) 2(η 2-O 2CMe)(η 2-bpy)] + (3), and [Ru 2(μ-dppm) 2(μ-CO) 2(η 2-bpy) 2] 2+ (4). Alternatively compound 2 can be prepared from the reaction of 1a with MeCO 2H–Et 3N, while compound 4 can be obtained from the reaction of 3 with bpy. The reaction of 1b with acetylacetone–Et 3N produces [Ru 2(μ-dppm) 2(μ-CO) 2(η 2-O 2CMe)(η 2-acac)] (5) and [Ru 2(μ-dppm) 2(μ-CO) 2(η 2-acac) 2] (6). Compound 2 can also react with acetylacetone–Et 3N to produce 6. Surprisingly [Ru 2(μ-dppm) 2(μ-CO) 2(η 2-quin) 2] (7) was obtained stereospecifically as the only one product from the reaction of 1b with 8-quinolinol–Et 3N. The structure of 7 has been established by X-ray crystallography and found to adopt a cis geometry. Further, the stereospecific reaction is probably caused by the second-sphere π–π face-to-face stacking interactions between the phenyl rings of dppm and the electron-deficient six-membered ring moiety of the bound quinolinate (i.e. the N-included six-membered ring) in 7. The presence of such interactions is indeed supported by an observed charge-transfer band in a UV–vis spectrum. 相似文献
17.
The hydrothermal reactions of vanadium oxide starting materials with divalent transition metal cations in the presence of nitrogen donor chelating ligands yield the bimetallic cluster complexes with the formulae [{Cd(phen 2) 2V 4O 12]·5H 2O (1) and [Ni(phen) 3] 2[V 4O 12]·17.5H 2O (2). Crystal data: C 48H 52Cd 2N 8O 22V 4 (1), triclinic.
a=10.3366(10), b=11.320(3), c=13.268(3) Å, =103.888(17)°, β=92.256(15)°, γ=107.444(14)°, Z=1; C 72H 131N 12Ni 2O 29.5V 4 (2), triclinic.
a=12.305(3), b=13.172(6), c=15.133(4), =79.05(3)°, β=76.09(2)°, γ=74.66(3)°, Z=1. Data were collected on a Siemens P4 four-circle diffractometer at 293 K in the range 1.59° <θ<26.02° and 2.01°<θ<25.01° using the ω-scan technique, respectively. The structure of 1 consists of a [V 4O 12] 4− cluster covalently attached to two {Cd(phen) 2} 2+ fragments, in which the [V 4O 12] 4− cluster adopts a chair-like configuration. In the structure of 2, the [V 4O 12] 4− cluster is isolated. And the complex formed a layer structure via hydrogen bonds between the [V 4O 12] 4− unit and crystallization water molecules. 相似文献
18.
The first carbonyl molybdenum-(O) and -(II) complexes with phenylbis(2-pyridyl)phosphine (PPhpy 2) have been synthesized. PPhpy 2 reacts with [Mo(CO) 5(NCMe)] to give [Mo(CO) 5(PPhpy 2- P)]. With [Mo(CO) 4(NBD)] (NBD = norbornadiene) it gives [Mo(CO) 4(PPhpy 2- P) 2] when a 2 : 1 ratio is used, or [MO(CO) 4(py 2PhP--- N, N′)] for a 1 : 1 ratio. Decarbonylation of any of these pyridylphosphine complexes leads to an oligomer of formula {MO(CO) 3(μ-PPhpy 2)} n, which is also obtained after heating [MO(CO) 6] in solution with an equimolar amount of PPhpy 2. The oligomer undergoes oxidative addition by iodine or allylbromide to give [MoI 2(CO) 3(py 2PhP--- N, N′)], or [MoBr(η 3-CH 2CHCH 2)(CO) 2(py 2PhP--- N, N′)], respectively. These complexes are also obtained by addition of equimolar amounts of PPhpy 2 to solutions of [MoI 2(CO) 3(NCMe) 2] and MoBr(η 3-CH 2CH CH 2)(CO) 2(NCMe) 2, respectively. The ligand tends to act as a P-donor towards molybdenum(O) substrates, and as a chelating N, N′-donor in molybdenum (II) complexes. 相似文献
19.
Structure—gas chromatographic retention time models were developed for 26 tetra- n-alkylsilanes, 26 tetra- n-alkylgermanes, and the mixed set of silanes and germanes using topological indexes. The topological indexes used were molecular connectivity indexes, the new Kier—Hall total topological indexes, and the new Kier—Hall electrotopological state atom index, S, for the silicon and germanium atoms. For the mixed data set, a model based on 1χ, 3χ c, and S gave r = 0.999 and s = 0.033. In two cases the residual was more than twice the standard error. Replacement of 1χ by TTV, the new Kier—Hall total topological index using δ v values for the silicon and germanium atoms, also gave r = 0.999 and s = 0.033 but in no case was there a residual greater than twice the standard error. A two-variable model based on 0χ r, which uses δ r values for the metal atoms, and 4χ pcv, which uses δ v values for the metal atoms gave r = 0.999 and s = 0.035. The results demonstrate the adequacy of the Kier—Hall electrotopological state atom index for encoding the atomic characteristics of silicon and germanium in a mixed data set. The results show that the Kier—Hall total topological indexes can be used in place of 1χ to encode the size and skeletal branching of silanes and germanes. 相似文献
20.
A Doppler-based velocity selection technique has been used to measure the relative velocity dependence of the cross sections σ ji,Δ(ν r) for rotationally inelastic collisions from level ji to ji + Δν 1 = 8,22,42) in 7Li *2 A 1Σ +u)—Xe. The σ jν±2(ν r) are strongly attenuated at a smaller ν r by “torque averaging” due to molecular rotation; in contrast, for large |Δ|, σ jiΔ = ν r−n (1 n 2). An empirical intermolecular potential which reproduces these types of behavior for 3-D classical trajectories is exhibited. 相似文献
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