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1.
New Experimental Insight into the Nature of Metal−Metal Bonds in Digallium Compounds: J Coupling between Quadrupolar Nuclei
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Dr. Libor Kobera Scott A. Southern Dr. Gyandshwar Kumar Rao Prof. Dr. Darrin S. Richeson Prof. Dr. David L. Bryce 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(28):9565-9573
Multiple bonding between atoms is of ongoing fundamental and applied interest. Here, we report a multinuclear (1H, 13C, and 71Ga) solid‐state magnetic resonance spectroscopic study of digallium compounds which have been proposed, albeit somewhat controversially, to contain single, double, and triple Ga?Ga bonds. Of particular relevance to the nature of these bonds, we have carried out two‐dimensional 71Ga J/D‐resolved NMR experiments which provide a direct measurement of J(71Ga,71Ga) spin–spin coupling constants across the gallium?gallium bonds. When placed in the context of clear‐cut experimental data for analogous singly, doubly, and triply bonded carbon spin pairs or boron spin pairs, the 71Ga NMR data clearly support the notion of a different bonding paradigm in the gallium systems. Our findings are consistent with an increasing role across the purported gallane–gallene–gallyne series for classical and/or slipped π‐type bonding orbitals. 相似文献
2.
Three Lewis acid–base adducts t‐Bu3Ga–EPh3 (E = P 1 , As 2 , Sb 3 ) were synthesized by reactions of Ph3E and t‐Bu3Ga and characterized by heteronuclear NMR (1H, 13C (31P)) and IR spectroscopy, elemental analysis and single crystal X‐ray diffraction. Their structural parameters are discussed and compared to similar t‐Bu3Ga adducts. The strength of the donor‐acceptor interactions within 1 – 3 was investigated in solution by temperature‐dependent 1H NMR spectroscopy and by quantum chemical calculations. 相似文献
3.
High‐resolution solid‐state 109Ag and 31P NMR spectroscopy was used to investigate a series of silver dialkylphosphite salts, Ag(O)P(OR)2 (R = CH3, C2H5, C4H9 and C8H17), and determine whether they adopt keto, enol or dimer structures in the solid state. The silver chemical shift, CS, tensors and |J(109Ag, 31P)| values for these salts were determined using 109Ag (Ξ = 4.652%) NMR spectroscopy. The magnitudes of J(109Ag, 31P) range from 1250 ± 10 to 1318 ± 10 Hz and are the largest reported so far. These values indicate that phosphorus is directly bonded to silver for all these salts and thus exclude the enol structure. All 31P NMR spectra exhibit splittings due to indirect spin–spin coupling to 107Ag (I = 1/2, NA = 51.8%) and 109Ag (I = 1/2, NA = 48.2%). The 1J(109Ag, 31P) values measured by both 109Ag and 31P NMR spectroscopy agree within experimental error. Analysis of 31P NMR spectra of stationary samples for these salts allowed the determination of the phosphorus CS tensors. The absence of characteristic P?O stretching absorption bands near 1250 cm?1 in the IR spectra for these salts exclude the simple keto tautomer. Thus, the combination of solid‐state NMR and IR results indicate that these silver dialkylphosphite salts probably have a dimer structure. Values of silver and phosphorus CS tensors as well as 1J(109Ag, 31P) values for a dimer model calculated using the density functional theory (DFT) method are in agreement with the experimental observations. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
4.
《Magnetic resonance in chemistry : MRC》2003,41(4):253-259
Experiments for 1H‐detected heteronuclear 1H,X correlation spectroscopy with 31P‐relayed coherence transfer are described which allow the indirect detection of δX and nJ(X,P) even in the absence of a direct J(X,H) coupling. The use of these techniques for the assignments of 13C, 15N, and 183W NMR data of organophosphorus compounds is demonstrated. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
5.
《Magnetic resonance in chemistry : MRC》2002,40(2):107-113
A survey of the use of 187Os satellite subspectra in 1H and 31P{1H} spectra of triosmium carbonyl clusters is reported. By varying evolution delays in HMQC spectra of [Os3(µ‐H)2(CO)10] we have selectively extracted the values for 1J(Os,H) and 2J(Os,H), respectively. An analysis of the principal modes of phosphine coordination in triosmium clusters demonstrates that 31P{1H}187Os satellite subspectra are diagnostic for equatorial coordination [1J(Os,P) = 211–223 Hz] or for axial coordination (perpendicular to the plane of the cluster) [1J(Os,P) ≈ 147 Hz]. Chelating and bridging diphosphines yield 187Os satellite subspectra which are the sum of A2X and AA′X spin systems. If significant P–P coupling is present, the AA′X component requires simulation. All observed 2J(Os,P) trans‐equatorial couplings fall in the range 38–65 Hz. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
6.
Fedushkin IL Nikipelov AS Morozov AG Skatova AA Cherkasov AV Abakumov GA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(1):255-266
Acetylene, phenylacetylene, and alkylbutynoates add reversibly to (dpp‐bian)Ga–Ga(dpp‐bian) (dpp‐bian=1,2‐bis[(2,6‐diisopropylphenyl)‐imino]acenaphthene) to give addition products [dpp‐bian(R1C?CR2)]Ga–Ga[(R2C?CR1)dpp‐bian]. The alkyne adds across the Ga? N? C section, which results in new carbon–carbon and carbon–gallium bonds. The adducts were characterized by electron absorption, IR, and 1H NMR spectroscopy and their molecular structures have been determined by single‐crystal X‐ray analysis. According to the X‐ray data, a change in the coordination number of gallium from three [in (dpp‐bian)Ga–Ga(dpp‐bian)] to four (in the adducts) results in elongation of the metal–metal bond by approximately 0.13 Å. The adducts undergo a facile alkynes elimination at elevated temperatures. The equilibrium between [dpp‐bian(PhC?CH)]Ga–Ga[(HC?CPh)dpp‐bian] and [(dpp‐bian)Ga–Ga(dpp‐bian) + 2 PhC?CH] in toluene solution was studied by 1H NMR spectroscopy. The equilibrium constants at various temperatures (298≤T≤323 K) were determined, from which the thermodynamic parameters for the phenylacetylene elimination were calculated (ΔG°=2.4 kJ mol?1, ΔH°=46.0 kJ mol?1, ΔS°=146.0 J K?1mol?1). The reactivity of (dpp‐bian)Ga–Ga(dpp‐bian) towards alkynes permits use as a catalyst for carbon–nitrogen and carbon–carbon bond‐forming reactions. The bisgallium complex was found to be a highly effective catalyst for the hydroamination of phenylacetylene with anilines. For instance, with [(dpp‐bian)Ga–Ga(dpp‐bian)] (2 mol %) in benzene more than 99 % conversion of PhNH2 and PhC?CH into PhN?C(Ph)CH3 was achieved in 16 h at 90 °C. Under similar conditions, the reaction of 1‐aminoanthracene with PhC?CH catalyzed by (dpp‐bian)Ga–Ga(dpp‐bian) formed a carbon–carbon bond to afford 1‐amino‐2‐(1‐phenylvinyl)anthracene in 99 % yield. 相似文献
7.
All J(P? H) and J(P? C) values, including signs, have been obtained in acetylenic and propynylic phosphorus derivatives, R2P(X)? C?C? H and R2P(X)? C?C? CH3 (X ? oxygen, lone pair and R ? C6H5, N(CH3)2, OC2H5, N(C6H5)2, Cl) from 1H and 13C NMR spectra. In PIV derivatives the following signs are obtained: 1J(P? C)+, 2J(P? C)+, 3J(P? C)+, 3J(P? H)+, 4J(P? H)? . Linear relations are observed between 1J(P? C), 2J(P? C) and 3J(P? C) versus 3J(P? H), indicating that these coupling constants are mainly dependent on the Fermi contact term, though the other terms of the Ramsey theory do not seem to be negligible for 1J(P? C) and 2J(P? C). In PIII derivatives these signs are: 1J(P? C)- and +, 2J(P? C)+, 3J(P? C)-, 3J(P? H)-, 4J(P? H)+. Only 3J(P? C) and 3J(P? H) reflect a small contribution of the Fermi contact term while in 1J(P? C) and 2J(P? C) this contribution seems to be negligible relative to the orbital and/or spin dipolar coupling mechanisms. 相似文献
8.
Synthesis and Structural Characterization of β‐Ketoiminate‐Stabilized Gallium Hydrides for Chemical Vapor Deposition Applications
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Dr. Peter Marchand Dr. David Pugh Prof. Ivan P. Parkin Prof. Claire J. Carmalt 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(33):10503-10513
Bis‐β‐ketoimine ligands of the form [(CH2)n{N(H)C(Me)?CHC(Me)?O}2] (LnH2, n=2, 3 and 4) were employed in the formation of a range of gallium complexes [Ga(Ln)X] (X=Cl, Me, H), which were characterised by NMR spectroscopy, mass spectrometry and single‐crystal X‐ray diffraction analysis. The β‐ketoimine ligands have also been used for the stabilisation of rare gallium hydride species [Ga(Ln)H] (n=2 ( 7 ); n=3 ( 8 )), which have been structurally characterised for the first time, confirming the formation of five‐coordinate, monomeric species. The stability of these hydrides has been probed through thermal analysis, revealing stability at temperatures in excess of 200 °C. The efficacy of all the gallium β‐ketoiminate complexes as molecular precursors for the deposition of gallium oxide thin films by chemical vapour deposition (CVD) has been investigated through thermogravimetric analysis and deposition studies, with the best results being found for a bimetallic gallium methyl complex [L3{GaMe2}2] ( 5 ) and the hydride [Ga(L3)H] ( 8 ). The resulting films ( F5 and F8 , respectively) were amorphous as‐deposited and thus were characterised primarily by XPS, EDXA and SEM techniques, which showed the formation of stoichiometric ( F5 ) and oxygen‐deficient ( F8 ) Ga2O3 thin films. 相似文献
9.
Anna Grünberg Dr. Xu Yeping Dr. Hergen Breitzke Dr. Gerd Buntkowsky Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(23):6993-6998
The Wilkinson’s catalyst [RhCl(PPh3)3] has been immobilized inside the pores of amine functionalized mesoporous silica material SBA‐3 and The structure of the modified silica surface and the immobilized rhodium complex was determined by a combination of different solid‐state NMR methods. The successful modification of the silica surface was confirmed by 29Si CP‐MAS NMR experiments. The presence of the Tn peaks confirms the successful functionalization of the support and shows the way of binding the organic groups to the surface of the mesopores. 31P‐31P J‐resolved 2D MAS NMR experiments were conducted in order to characterize the binding of the immobilized catalyst to the amine groups of the linkers attached to the silica surface. The pure catalyst exhibits a considerable 31P‐31P J‐coupling, well resolvable in 2D MAS NMR experiments. This J‐coupling was utilized to determine the binding mode of the catalyst to the linkers on the silica surface and the number of triphenylphosphine ligands that are replaced by coordination bonds to the amine groups. From the absence of any resolvable 31P‐31P J‐coupling in off‐magic‐angle‐spinning experiments, as well as slow‐spinning MAS experiments, it is concluded, that two triphenylphosphine ligands are replaced and that the catalyst is bonded to the silica surface through two linker molecules. 相似文献
10.
Donor‐stabilized Galliumdihalides Ga2X4·2D (X = Cl, Br; D = Donor): An Experimental Contribution on the Variation of the Gallium‐Gallium Single Bond During the disproportionation of metastable GaX‐solutions (X= Cl, Br) donor‐stabilized galliumdihalides are formed as oxidized products. According to X‐ray structure analyses they all exhibit dimeric entities DX2Ga‐GAX2D (D= THF, NHEt2, NEt3, 4‐tButylpyridin or Br‐), which means these compounds are isoelectronic with ethane and could schematically be regarded as representatives of catenulate or alkane‐like gallium subhalides: Gan(X, D)2n+2. The gallium‐gallium bond in these compounds is shorter than in the organometallic compounds such as R2Ga‐GaR2. The comparison of the bonding situation in the galliumdihalides, particularly of the gallium‐gallium bond, shows clearly the influence by donor molecules as well as by halogen ligands. 相似文献
11.
Simultaneous determination of the magnitude and the sign of multiple heteronuclear coupling constants in 19 F or 31P‐containing compounds
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The presence of a highly abundant passive nucleus (Z = 19 F or 31P) allows the simultaneous determination of the magnitude and the sign of up to three different heteronuclear coupling constants from each individual cross‐peak observed in a 2D 1H‐X selHSQMBC spectrum. Whereas J(HZ) and J(XZ) coupling constants are measured from E.COSY multiplet patterns, J(XH) is independently extracted from the complementary IPAP pattern generated along the detected F2 dimension. The incorporation of an extended TOCSY transfer allows the extraction of a complete set of all these heteronuclear coupling constants and their signs for an entire 1H subspin system. 1H‐X/1H‐Y time‐shared versions are also proposed for the simultaneous measurement of five different couplings (J(XH), J(YH), J(XZ), J(YZ), and J(ZH)) for multiple signals in a single NMR experiment. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
12.
The irreversible inhibition of δ‐chymotrypsin with the enantiomerically pure, P(3)‐axially and P(3)‐equatorially X‐substituted cis‐ and trans‐configurated 2,4‐dioxa‐3‐phospha(1,5,5‐2H3)bicyclo[4.4.0]decane 3‐oxides (X=F, 2,4‐dinitrophenoxy) was monitored by 31P‐NMR spectroscopy. 1H‐Correlated 31P{2H}‐NMR spectra enabled the direct observation of the vicinal coupling (3J) between the P‐atom of the inhibitor and the CH2O moiety of Ser195 (=‘Ser195’(CH2O)), thus establishing the covalent nature of the ‘Ser195’(CH2O? P) bond in the inhibited enzyme. The stereochemical course of the phosphorylation is dependent on the structure of the inhibitor, and neat inversion, both inversion and retention, as well as neat retention of the configuration at the P‐atom was found. 相似文献
13.
Bruce W. Tattershall Julian G. Knight Mark J. Andrews Claire L. Booth 《无机化学与普通化学杂志》2006,632(3):425-432
Reactions of bicyclic α‐P4S3I2 with Hpthiq gave solutions containing α‐P4S3(pthiq)I and α‐P4S3(pthiq)2, where Hpthiq is the conformationally constrained chiral secondary amine 1‐phenyl‐1,2,3,4‐tetrahydroisoquinoline. The expected diastereomers have been characterised by complete analysis of their 31P{1H} NMR spectra. Hindered P–N bond rotation in the amide iodide α‐P4S3(pthiq)I caused greater broadening of peaks in the room‐temperature spectrum of one diastereomer than in that of the other. At 183 K, spectra of two P–N bond rotamers for each diastereomer were observed and analysed. The minor rotamers showed strong evidence for steric crowding, having large diastereomeric differences in 1J(P–P) and 2J(P–S–P) couplings (49 Hz, 16 % of value, and 4.4 Hz, 19 % of value, respectively). 相似文献
14.
A novel fairly stable N‐trimethylsilylamino(dichloro)phosphine was prepared, in which the nitrogen atom bears a 9‐borabicyclo[3.3.1]nonyl group. The gas phase structures of various amino‐ and silylaminophosphines including a phosphenium cation and an amino(imono)phosphine were optimized at the B3LYP/6‐311+G(d,p) level of theory, and NMR parameters were calculated. Both magnitude and sign of the two‐bond coupling constants 2J(31P,N,13C) and 2J(31P,N,29Si), known to be sensitive towards the respective conformation, are well reproduced by the calculations. This also holds for 1J(31P,15N), although calculated values 1K(31P,15N) (all < 0) are slightly more negative [1J(31P,15N) more positive] than experimental values. 相似文献
15.
Louis D. Quin Keith A. Mesch Ryszard Bodalski K. Michal Pietrusiewicz 《Magnetic resonance in chemistry : MRC》1982,20(2):83-91
The easily obtained dimers of phosphole oxides, sulfides and methiodides give 13C NMR spectra where carbons within three (sometimes four) bonds of each 31P nucleus are doublets of doublets and thus constitute X in an AMX spectrum. Most of the spectra have been completely interpreted with the aid of spectral measurements at two magnetic fields. Saturation of the double bonds in dimers of methylphosphole–P(IV) derivatives causes the 31P nuclei to have very similar chemical shifts, with Δν not adequately different from 3J(PP) to give first-order coupling. When both 31P nuclei couple with a given 13C, a second-order (ABX) 31C NMR spectrum is obtained. The presence of the effect is revealed by running the 13C NMR spectra at high magnetic field; J(AX)+J(BX) is constant at all fields, but spacing between the lines of the multiplet varies. The spectrum of the oxide, with Δν/J=1.44 for the 31P spectrum at 36.43 MHz, approaches first order character at 75 MHz; the methiodide spectrum (Δν/J=4.55) is second order at 15 MHz but clearly first order at 50 MHz, and the sulfide (Δν/J=5.6) is nearly first order at 15 MHz. [2 + 2]-Photochemical intramolecular cyclization of the dimer oxides provides cage-like structures where the 31P nuclei are chemically equivalent, but magnetically non-equivalent, making the 13C signals have the characteristics of X in an AA′X coupling pattern. 相似文献
16.
Raymond Haran Jean-Pierre Laurent Grard Commenges 《Magnetic resonance in chemistry : MRC》1973,5(10):463-468
From an NMR (1H) study of various systems chloroalkylgallium/Lewis bases, it appears that the four types of gallium compounds (ClnR3?nGa) form adducts with trialkylamines, trialkylphosphines, ethers and sulphides, and that in all cases the 1:1 complex seems to be the only existing one. Its stability mainly depends on the number of chlorine atoms bound to the gallium and on the nature of the donor site. 相似文献
17.
Matthias Westerhausen Stefan Schneiderbauer Manfred Hartmann Marcus Warchhold Heinrich Nth 《无机化学与普通化学杂志》2002,628(2):330-332
The metalation of HP(SiMe3)2 with Y[CH(SiMe3)2]3 gives the homoleptic {Y[P(SiMe3)2]3}2 (1) which crystallizes from toluene in the monoclinic space group P21/c. The yttrium atoms are in a distorted tetrahedral environment with Y‐P bond lengths of 267.7 and 284.8 pm to the terminal and bridging substituents, respectively. The metathesis reaction of [1, 3‐(Me3Si)2C5H3]2YCl with KPSitBu3 yields (tetrahydrofuran‐O)‐1, 1', 3, 3'‐tetrakis(trimethylsilyl)yttrocene‐tri(tert‐butyl)silylphosphanide ( 2 ). The molecular structure of 2 in solution was deduced by NMR spectroscopy and X‐ray crystallography. The coupling constants 1J(Y, P) and 1J(P, H) show values of 144.0 Hz and 201.0 Hz, respectively. 相似文献
18.
Jean-Pierre Albrand Didier Gagnaire Jean Martin Jean-Bernard Robert 《Magnetic resonance in chemistry : MRC》1973,5(1):33-41
The proton NMR spectral analysis of eight different 1,3,2-dithiaphospholanes with various groups attached to the phosphorus atom has been performed. The AA′BB′X (X phosphorus atom) system shows that the two 3J(P? S? C? H) coupling constants have a small magnitude and opposite signs. Using the 3J(HH) values, the torsion about the C4—C5 bond has been evaluated. The conformational requirements in the two isomers of the 2 phenyl-4-methyl-1,3,2-dithiaphospholane are also discussed. 相似文献
19.
《Magnetic resonance in chemistry : MRC》2002,40(9):589-594
The 31P chemical shift (CS) tensors of the 1,3,2‐diazaphospholenium cation 1 and the P‐chloro‐1,3,2‐diazaphospholenes 2 and 3 and the 31P and 19F CS tensors of the P‐fluoro‐1,3,2‐diazaphospholene 4 were characterized by solid‐state 31P and 19F NMR studies and quantum chemical model calculations. The computed orientation of the principal axes system of the 31P and 19F CS tensors in the P‐fluoro compound was found to be in good agreement with experimentally derived values obtained from evaluation of P–F dipolar interactions. A comparison of the trends in the chemical shifts of 1 – 4 with further available literature data confirms that the unique high shielding of δ11 in the cation 1 can be related to the effective π‐conjugation in the five‐membered heterocycle, and that a further systematic decrease in δ11 for the P‐halogen derivatives 2 – 4 is attributable to the increased perturbation of the π‐electron distribution by interaction with the halide donor. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
20.
The diamide exo, exo‐β‐P4S3(NHCH(Me)Ph)2 has been made in solution using enantiomerically pure or racemic PhCH(Me)NH2, and its three diastereomers characterised by complete analysis of their 31P{1H} NMR spectra.The unsymmetric diastereomer contains phosphorus atoms, made chemically non‐equivalent by the chirality of the substituents, which show a large 2J(P—P—P) coupling to each other (225.2 Hz). 相似文献