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1.
In situ reaction of Li[ closo-1-Ph-1,2-C 2B 10H 10] with 7-azabicyclo [4.1.0] heptane results in the formation of the disubstituted carborane, closo-1-Ph-2-(2′-aminocyclohexyl)-1,2-C 2B 10H 10 (1), in 63% yield. Decapitation of (1) with potassium hydroxide in refluxing ethanol produces the cage-opened nido-carborane, K[ nido-7-Ph-8-(2′-aminocyclohexyl)-7,8-C 2B 9H 10] − (2), in 80% yield. Deprotonation of the above monoanion with two equivalents of n-butyllithium followed by reaction with anhydrous MCl 4 · 2THF (M = Zr, Ti) provides d0-half-sandwich metallocarboranes, closo-1-M(Cl)-2-Ph-3-(2′- σ-(H) N-cyclohexyl)-2,3- η5-C 2B 9H 9 (3 M = Zr; 4 M = Ti) in 53% and 42% yields, respectively. The reaction of Li[ closo-1,2-C 2B 10H 11] with 7-azabicyclo [4.1.0] heptane in THF affords closo-1-(2′-aminocyclohexyl)-1,2-C 2B 10H 10 (5) in 59% yield. Immobilization of the carboranyl amino ligand (1) to an organic support, Merrifield’s peptide resin (1%), has been achieved by the reaction of the sodium salt of (5) with polystyryl chloride in THF to produce closo-1-(2′-aminocyclohexyl)-2-polystyryl-1,2-C 2B 10H 10 (6) in 87% yield. Further reaction of the dianion derived from (6) with anhydrous ZrCl 4 · 2THF led to the formation of the organic polystyryl supported d0-half-sandwich metallocarborane, closo-1-Zr(Cl)-2-(2′- σ-(H) N-cyclohexyl)-3-polystyryl-2,3-η 5-C 2B 9H 9 (7), in 38% yield. These new compounds have been characterized by elemental analyses, NMR, and IR spectra. Polymerizations of both ethylene and vinyl chloride with (3) and (7) have been performed in toluene using MMAO-7 (13% ISOPAR-E) as the co-catalyst. Molecular weights up to 32.8 × 10 3 ( Mw/ Mn = 1.8) and 9.5 × 10 3 ( Mw/ Mn = 2.1) were obtained for PE and PVC, respectively. 相似文献
2.
Thermolysis of [ arachno-4-SB 8H 12] (1) in boiling cyclohexane gives two isomers 2 and 3 of 18-vertex [S 2B 16H 16], together with known 12-vertex [ closo-1-SB 11H 11] (4) and known 11-vertex [ nido-7-SB 10H 12] (5). Compounds 2 and 3 are characterised by single-crystal X-ray diffraction analyses and single- and double-resonance 11B- and 1H-NMR spectroscopy. The [ n-S 2B 16H 16] isomer 2 takes the form of nido ten-vertex: nido ten-vertex [ anti-B 18H 22] with the 9 and 9′ positions occupied by S vertices, whereas the [ iso-S 2B 16H 16] isomer 3 takes the form of a nido 11-vertex {SB 10} subcluster fused via a common two-boron edge to a nido-type {B 8} subcluster that is additionally linked exo to the {SB 10} subcluster by a bridging S atom that is held endo to the {B 8} unit. Isomer 2 is readily deprotonated and its monoanion 6 is characterised by NMR spectroscopy and by a single-crystal X-ray diffraction analysis of its [tmndH] +[ n-S 2B 16H 15] salt 6b; deprotonation has occurred from an open-face B---H---B bridging site. 相似文献
3.
The reactions of RNHSi(Me) 2Cl (1, R= t-Bu; 2, R=2,6-(Me 2CH) 2C 6H 3) with the carborane ligands, nido-1-Na(C 4H 8O)-2,3-(SiMe 3) 2-2,3-C 2B 4H 5 (3) and Li[ closo-1-R′-1,2-C 2B 10H 10] (4), produced two kinds of neutral ligand precursors, nido-5-[Si(Me) 2N(H)R]-2,3-(SiMe 3) 2-2,3-C 2B 4H 5, (5, R= t-Bu) and closo-1-R′-2-[Si(Me) 2N(H)R]-1,2-C 2B 10H 10 (6, R= t-Bu, R′=Ph; 7, R=2,6-(Me 2CH) 2C 6H 3, R′=H), in 85, 92, and 95% yields, respectively. Treatment of closo-2-[Si(Me) 2NH(2,6-(Me 2CH) 2C 6H 3)]-1,2-C 2B 10H 11 (7) with three equivalents of freshly cut sodium metal in the presence of naphthalene produced the corresponding cage-opened sodium salt of the “carbons apart” carborane trianion, [ nido-3-{Si(Me) 2N(2,6-(Me 2CH) 2C 6H 3)}-1,3-C 2B 10H 11] 3− (8) in almost quantitative yield. The reaction of the trianion, 8, with anhydrous MCl 4 (M=Ti and Zr) in 1:1 molar ratio in dry tetrahydrofuran (THF) at −78 °C, resulted in the formation of the corresponding half-sandwich neutral d 0-metallacarborane, closo-1-M[(Cl)(THF) n]-2-[1′-η 1σ-N(2,6-(Me 2CH) 2C 6H 3)(Me) 2Si]-2,4-η 6-C 2B 10H 11 (M=Ti (9), n=0; M=Zr (10), n=1) in 47 and 36% yields, respectively. All compounds were characterized by elemental analysis, 1H-, 11B-, and 13C-NMR spectra and IR spectra. The carborane ligand, 7, was also characterized by single crystal X-ray diffraction. Compound 7 crystallizes in the monoclinic space group P2 1/ c with a=8.2357(19) Å, b=28.686(7) Å, c=9.921(2) Å; β=93.482(4)°; V=2339.5(9) Å 3, and Z=4. The final refinements of 7 converged at R=0.0736; wR=0.1494; GOF=1.372 for observed reflections. 相似文献
4.
A new series of rigid-rod alkynylferrocenyl precursors with central fluoren-9-one bridge, 2-bromo-7-(2-ferrocenylethynyl)fluoren-9-one (1b), 2-trimethylsilylethynyl-7-(2-ferrocenylethynyl)fluoren-9-one (2) and 2-ethynyl-7-(2-ferrocenylethynyl)fluoren-9-one (3), have been prepared in moderate to good yields. The ferrocenylacetylene complex 3 can provide a direct access to novel heterometallic complexes, trans-[(η 5-C 5H 5)Fe(η 5-C 5H 4)CCRCCPt(PEt 3) 2Ph] (4), trans-[(η 5-C 5H 5)Fe(η 5-C 5H 4)CCRCCPt(PBu 3) 2CCRCC(η 5-C 5H 4)Fe(η 5-C 5H 5)] (5), [(η 5-C 5H 5)Fe(η 5-C 5H 4)CCRCCAu(PPh 3)] (6) and [(η 5-C 5H 5)Fe(η 5-C 5H 4)CCRCCHgMe] (7) (R=fluoren-9-one-2,7-diyl), following the CuI-catalyzed dehydrohalogenation reactions with the appropriate metal chloride compounds. All the new complexes have been characterized by FTIR, 1H-NMR and UV–vis spectroscopies and fast atom bombardment mass spectrometry. The solid state molecular structures of 3, 5, 6 and 7 have been established by X-ray crystallography. The redox chemistry of these mixed-metal species has been investigated by cyclic voltammetry and oxidation of the ferrocenyl moiety is facilitated by the presence of the heavy metal centre and increased conjugation in the chain through the ethynyl and fluorenone linkage units. 相似文献
5.
The reaction of the labelled carborane ligand [3-Et-7,8-Ph 2-7,8- nido-C 2B 9H 8] 2− with a source of {Pt(PMe 2Ph) 2} 2+ affords non-isomerised 1,2-Ph 2-3,3-(PMe 2Ph) 2-6-Et-3,1,2- closo-PtC 2B 9H 8 (1). The analogous reaction between [3-F-7,8-Ph 2-7,8- nido-C 2B 9H 8] 2− and {Pt(PMe 2Ph) 2} 2+ yields 1,8-Ph 2-2,2-(PMe 2Ph) 2-4-F-2,1,8- closo-PtC 2B 9H 8 (3). Compound 1 has a heavily slipped structure ( Δ 0.72 Å), which to some degree obviates the need for C atom isomerisation. However, that it is a kinetic product of the reaction is evident from the fact that it reverts to isomerised 1,8-Ph 2-2,2-(PMe 2Ph) 2-4-Et-2,1,8- closo-PtC 2B 9H 8 (2) slowly at room temperature but more rapidly with gentle warming. The heteroatom and labelled-B atom positions in the isomerised compounds 2 and 3 may be explained most simply by the rotation of a CB 2 face of an intermediate based on the structure of 1. Compounds 1–3 were characterised by a combination of spectroscopic and crystallographic techniques. 相似文献
6.
Nine compounds, namely Li 3BO 3, -Li 4B 2O 5, β-Li 4B 2O 5, Li 6B 4O 9, -LiBO 2, Li 2B 4O 7, Li 3B 7O 12, LiB 3O 5 and Li 2B 8O 13 in the Li 2O–B 2O 3 system have been synthesized and characterized. The unit-cell parameters, density and solubility in water at room temperature of all the compounds are reported. The densities of the compounds were found to be in the 1.90–2.50 g cm −3 range, while their solubility in water at room temperature was in the 0.91–8.64×10 −2 g cm −3 range. Determination of the thermal stability of the compounds by quenching and differential thermal analysis (DTA) showed that only -LiBO 2 and Li 2B 4O 7 retained their original symmetry up to their congruent melting at 1121 and 1188 K, respectively, in air. 相似文献
7.
In the reaction of cis-(CO) 4(SnPh 3)Re[C(OEt)NR 2] (R = ipr (isopropyl), chex (cyclohexyl)) with BI 3 the Lewis acid attacks the triphenylstannyl ligand. Substitution of a phenyl for a iodine group leads to equilibrium mixtures of rhenium carbene complexes of general formula cis-(CO) 4(SnPh 3−χI χ)Re[C(OEt)NR 2] (χ = 1−3; R = ipr, chex). By changing the solvent and ratio of can be shifted such that only one major product is formed. Thus this reaction pathway can be used for the preparation of cis-(CO) 4(SnPhI 2)Re[C(OEt)NR 2] (R = ipr, chex). Even when a large excess of BI 3 is present electrophilic attack by the Lewis acid on the carbene ligand is not observed. Synthesis of cis-(CO)4(SnPh3−χIχ)Re[C(OEt)NR2] (χ = 1−3; R --- ipr, chex) can be achieved in high yield by reaction of cis-(CO)4(SnPh3)Re[C(OEt)NR2] (R = ipr, chex) with one, two or three equivalents of HI. This reaction, with successive rupture of the tin-carbon bonds in the triphenylstannyl ligand and the simultaneous formation of benzene, affords the desired substitution product irreversibly. Reaction of cis-(CO)4(SnPh3)Re[C(OEt)NR2] (R = ipr, chex) with I2 gives the compounds, cis-(CO)4(SnI3)Re[C(OEt)NR2] (R = ipr, chex), in relatively low yields. 相似文献
8.
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
9.
The new 11-vertex nido-diphosphaborane, 7,9-Ph 2- nido-7,9-P 2B 9H 9, has been synthesized by the reaction of Me 4N +[ nido-B 9H 12−] with PhPCl 2 in the presence of NaH. A single crystal X-ray diffraction determination and DFT/GIAO/NMR methods have both established that the compound has an open cage structure containing the phosphorus atoms in non-adjacent positions on the open face. 相似文献
10.
Effects of sintering atmospheres on properties of SrCo 0.4Fe 0.5Zr 0.1O 3−δ mixed-conducting membranes were in detail studied in terms of sintering behavior, electrical conductivity and oxygen permeability. The sintering atmospheres were 100% N 2, 79% N 2–21% O 2, 60% N 2–40% O 2, 40% N 2–60% O 2, 20% N 2–80% O 2 and 100% O 2 (in vol.%), and the prepared membranes were correspondingly denoted as S-0, S-21, S-40, S-60, S-80 and S-100, respectively. It was found that the properties of membranes were strongly dependent on the sintering atmosphere. As the oxygen partial pressure in the sintering atmosphere ( PO2) increased, sintering ability, electrical conductivity and oxygen permeability decreased at first, which was in the order of S-0 > S-21 > S-40. However, as PO2 increased further, sintering ability, electrical conductivity and oxygen permeability increased gradually: S-40 < S-60 < S-80 < S-100. And the S-100 membrane had the best sintering ability, electrical conductivity and oxygen permeability in all membranes. 相似文献
11.
An S,S′-thioether—thioester chelating ligand [7,8- μ-SCH 2C(O)S-7,8-C 2B 9H 10] − (L 1), incorporating the unit [—(C) 2B 9H 10] − has been synthesized. Reactions have been conducted with RhCl(PPh 3) 3 and PdCl 2(PPh 3) 2 complexes in ethanol. With Rh, L 1 maintains its original cyclic nature and most probably chelation via thioether—thioester takes place. The carborane negative charge may stabilize this original thioether—thioester complex. The other two Rh positions are occupied by two PPh 3 ancillary ligands forming [Rh(L 1)(PPh 3) 2]. The reaction of L 1 with Pd induces ligand modifications and the cyclic nature of L 1 is lost. A transesterification process leading to a dianionic ligand L 2, [7-S-8-SCH 2C(O)OCH 2CH 3−7,8-C 2B 9H 10] 2− has taken place. In this way L 2 is capable of compensating the dipositive Pd charge. The other two Pd positions are occupied by two PPh 3. This reaction has been extended to methanol and isopropanol solvents. The crystal structure of [Pd(L 2)(PPh 3) 2] has been determined. 相似文献
12.
Reaction of cis-[Ptph 2(SMe 2) 2] with Me 2PCH 2PMe 2 (dmpm) gave cis-[PtPh 2(dmpm-P) 2] (1) or cis,cis-[Pt 2Ph 4(μ-dmpm) 2] (2) and reaction of 1 with [Pt 2Me 4(μ-SMe 2) 2] gave cis,cis-[Ph 2Pt(μ-dmpm) 2PtMe 2] (3). Reaction of 1 with trans-[PtClR(SMe 2) 2] gave cis, trans-[Ph 2Pt(μ-dmpm) 2PtClR], R = Me (5) or Ph (6), and in polar solvents, these isomerized to give [Ph 2Pt(μ-dmpm) 2PtR] +Cl −. When R = Me, further isomerization via the phenyl group transfer gave [PhMePt(μ-dmpm) 2PtPh] +Cl −. Oxidative addition of methyl iodide occurred reversibly at the cis-[PtMe 2P 2 unit of 3 to give cis, fac-[Ph 2Pt(μ-dmpm) 2PtIMe 3] but complex 2 failed to react with MeI. A comparison with similar known complexes of Ph 2PCH 2PPh 2 (dppm) is made and differences are attributed primarily to the lower steric hindrance of dmpm. 相似文献
13.
Reaction of phenyl magnesium bromide with the ,β-unsaturated ketone 3-methyl-2,3,4,5,6,7-hexahydroind-8(9)-en-1-one, followed by an aqueous work-up, generates the pro-chiral tetra-substituted cyclopentadiene, 1-phenyl-3-methyl-4,5,6,7-tetrahydroindene, Cp ‡H, a precursor to the η 5-cyclopentadienyl ligand in (Cp ‡) 2Fe and [(Cp ‡)Fe(CO)] 2(μ-CO) 2. Both complexes were generated as mixtures of rac-( RR and SS)- and meso-( RS)-isomers, and in either case pure meso-isomer was isolated by crystallisation and characterised by single crystal X-ray structure, both molecules having crystallographic Ci symmetry. Reduction with Na/Hg cleaves meso-( RS)-[(Cp ‡)Fe(CO)] 2(μ-CO) 2 and the resulting mixture of ( R)- and ( S)-[(Cp ‡)Fe(CO) 2] − anions reacts with MeI to give racemic (Cp ‡)Fe(CO) 2Me, which was characterised by the X-ray crystal structure. The Cp ‡ ligand is more electron donating than (η-C 5H 5) as revealed by the reduction potential of the (Cp ‡) 2Fe +/(Cp ‡) 2Fe couple, E°=−0.127 V (vs. Ag AgCl). Reaction of LiCp ‡ with ZrCl 4 yields the zirconocene dichloride [Zr(Cp ‡) 2Cl 2] as mixture of rac- and meso-isomers, from which pure rac-isomer is obtained as a mixture of RR and SS crystals by recrystallisation. The reaction of rac-[Zr(Cp ‡) 2Cl 2] with LiMe gives rac-[Zr(Cp ‡) 2Me 2]. The structures of RR-[Zr(Cp ‡) 2Cl 2] and rac-[Zr(Cp ‡) 2Me 2] have been determined by X-ray diffraction. The structural studies reveal the influence of the bulky substituted cyclopentadienyl ligand on the metal---Cp ‡ distances and other metric parameters. 相似文献
14.
An investigation of the frontier molecular orbitais of o- and p-RC 6H 4NC (R=H, CH 3, NO 2, F, Cl, CF 3, OCH 3) was carried out so that a thorough understanding of the intricacies of σ donation and π acceptance could be developed and used to modify subtly the electron density on metal centers. The results of this study-Indicate that the substituent position (ortho vs. para ) does alter the electron density in the ligand appreciably and that substitution of the phenyl ring with the groups indicated has a smaller effect on the σ-donating ability than it does on the π-accepting ability of the isonitrile ligand. The π-accepting abilities of the isonitrile ligands increase in the order o-, p-CH3OC6H4NC, o-, p-CH3C6H4NC, o-, p-C6H5NC, o-, p-FC6H4NC, o-, p-CF3C6NC, o-, p-ClC6H4NC, o-, p-NO2C6H4NC while the σ-donating ability decreases in this order. The energies of the σ-donor and π-acceptor orbitais are shown to correlate well with observed E
values of Cr(RC6H4NC)6 and Mn(RC6H4NC)6+1 complexes. This demonstrates how the theoretical results can be useful in understanding the observed physical properties of isonitrile-metal complexes. 相似文献
15.
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
16.
The influence of the –NH 2 group position in the pyridine ring on the proton donor ability of N–H groups in hydrogen bonding as well as on the spectral behaviour of stretching and bending vibrations of aminopyridines has been studied. The proton donor ability was shown to increase in the row: meta-, ortho-, and para-aminopyridines. It was established tha N–H bonds in ortho-aminopyridine were not equivalent, and the evaluation of their dynamic nonequivalence was made. The influence of temperature on the spectral characteristics of the absorption bands of the stretching vibrations of amine groups in the free and hydrogen bonded molecules in CCl4 has been studied (in temperature range 290–330 K), the formation constants of the complexes have been determined, enthalpy of the 1:1 complexes formation (−ΔH1) between ortho- and meta-aminopyridines with dimethylformamide, dimethylsulphoxide and hexamethylphosphoramide has been calculated in temperature range 290–330 K. The 1:2 complexes of ortho-, meta- and para-aminopyridines with acetonitrile, tetrahydrofurane, dimethylsulphoxide, hexamethylphosphoramide were studied at the indoor temperature. Enthalpy of the 1:2 complex (−ΔH2) was estimated on the basis of ‘intensity rule’; −ΔH1=ΔB1/2 assuming that parameter does not depend on the composition of a complex. The vibrational and electrooptical tasks were solved for the free and H-bounded molecules of aminopyridines as well as its complexes of the 1:1 and 1:2 compositions. Dynamic, electrooptical and energetic nonequivalency of NH bonds of aminogroups in aminopyridines was studied quantitatively. The independent calculations of dynamic constants proved mentioned above nonequivalency of NH bonds. Correlations between spectral characteristics of the absorption bands, geometric, dynamic and electrooptical parameters of –NH2 group in aminopyridines in the free and hydrogen bonded molecules have been established. Those correlations allow to determine the most important molecular characteristics obtained on the basis of spectral measurements in the range of the absorption bands of the stretching vibrations of aminogroup. 相似文献
17.
[H(DMSO) 2][ trans-RuCl 4(DMSO) 2] (1) reacts with 2,2′-bipyridine in ethanol at room temperature resulting in the formation of a major compound, mer-[RuCl 3(DMSO)(bpy)] (bpy = 2,2′-bipyridine) 3 and a known minor compound, cis-[RuCl 2(DMSO) 4] (4). The compounds 3 and 4 are formed via an anticipated intermediate mer-[RuCl 3(DMSO) 3] (2). The reaction of 3 and mer-[RuCl 3(TMSO)(bpy)] (5) with small molecules like imidazole, carbon monoxide and KSCN yield, mer-[RuCl 3(bpy)(im)] · 2DMSO (im = imidazole) (6) and cis-[RuCl 2(TMSO)(CO)(bpy)] (7), cis-[RuCl 2(DMSO)(CO)(bpy)] (8) and K[RuCl 3(bpy)(SCN)] (9), respectively. The formations of 3, 6 and 7 have been authenticated by single crystal structure determinations. Compound 6 is formed by the substitution of DMSO or TMSO from 3 and 5, respectively, whereas 7 and 8 are formed by unprecedented one-electron reductions of 5 and 3. The reactions of 3 and 5 with KSCN resulted in the same compound, K[RuCl 3(NCS)(bpy)] (9). DFT calculations were performed to distinguish whether the thiocyanate ligand is bound to ruthenium through S or N. In the ruthenium bipyridine systems, the HOMO contains ruthenium d-orbitals and the LUMO is typically π *-orbitals of the bipyridine ring. Complexes 3, 6 and 7 are redox active in acetone and DMSO solvent showing prominent a reduction peak and corresponding oxidation peak. 相似文献
18.
Ultra-soft X-ray fluorescence spectra of ortho- and meta-carborane C 2B 10H 12 were obtained. Ab initio self-consistent field (SCF) quantum-chemical calculations of these molecules were performed to interpret BK and CK spectra. Distinctions between electronic structure of closo-carboranes 1,2- and 1,7-C 2B 10H 12 are caused by different efficiency in the interaction of carbon and boron atoms. Location of boron atom between carbon atoms leads to stronger delocalization of electron density in meta-carborane molecule. The correlation between molecular orbitals (MOs) of the anion B 12H 122− and the closo-carboranes was carried out. 相似文献
19.
For a closed-shell MO configuration with 2 n electrons which occupy n non-degenerate canonical MOs, it is deduced that the RHF energy, Σ ni=1[2 H0n+Σ nj-1(2 Jij-K ij)], may be expressed in Hückel-like form as 2Σ ni-1ε, −Σ ni-1[ ji(λ+1)+1,(λ+2)] with λ=2( n- i). The l i(λ+1) and Ii(λ+2) are the ionization potentials for the HOMO ψ, which arises after λ and λ+1 electrons have been successively removed from the initial configuration. 相似文献
20.
The molecular and crystal structure of the nido-6-tungstadecaborane [6,6,6,6-(CO) 2(PPh 3) 2- nido-6-WB 9H 13] (1) has been determined showing that the tungsten atom is incorporated into the 6-position of a nido 10-vertex (WB 9) cage. The tungsten atom has a seven-coordinate capped trigonal prismatic environment and is bonded to two hydrogen and three boron atoms of the {B 9H 13} cage, in addition to two CO groups and two PPh 3 ligands. Variable-temperature (−90°C to +50°C) 31P{ 1H} NMR spectroscopy of 1 reveals that the exo-polyhedral ligands about the tungsten atom are fluxional with respect to PPh 3 site exchange with an activation energy (Δ G‡), at the coalescence temperature (−73°C), of <38 kJ mol −1. 相似文献
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