STERIC AND ELECTRONIC DESTABILIZATION OF THE P—Se BOND IN TRIARYLPHOSPHINE SELENIDE SYSTEMS

Abstract

Electronic and steric effects in SeP(Ar), compounds are discussed with the assistance of ¹J(⁷⁷Se-³¹P) correlations with d(P—Se) values and the pKa of the arylphosphines.     

Tris(dimethylamino)phosphine Selenide Complexes of Cadmium(II): Synthesis and Multinuclear (31P, 77Se,and 113Cd) NMR Characterization in Solution

The complexes CdL₄(ClO₄)₂ (1), CdL₂(NO₃)₂ (2), and CdL₂Cl₂ (3) (L = (Me₂N)₃P(Se)) have been prepared and characterized by elemental analysis, conductivity measurements, IR, and multinuclear (³¹P, ⁷⁷Se, and ¹¹³Cd) NMR spectroscopy. ³¹P and ⁷⁷Se NMR data were informative of changes associated with complex formation. The structure of the prepared complexes was further confirmed in solution by their ¹¹³Cd NMR spectra, which show a quintuplet for the perchlorate complex and a triplet for each of the nitrate and chloride complexes due, respectively, to coupling with four and two equivalent phosphorus atoms, consistent with a four coordinate tetrahedral geometry for the cadmium center. The NMR data are discussed and compared with those reported for related complexes.     

Tris(dialkylamino)phosphine Chalcogenide Complexes of Tin(IV) Chloride: A Multinuclear (31P, 77Se,and 119Sn) NMR Characterization

Abstract

Four octahedral complexes of the type SnCl₄.2L [L = (R₂N)₃P(E): E = Se; R = Me(1), Et(2) and E = S; R = Me(3), Et(4)] have been studied in solution by multinuclear (³¹P, ⁷⁷Se, and ¹¹⁹Sn) NMR spectroscopy. ³¹P and ⁷⁷Se NMR data were informative of changes associated with complex formation. The solution structure of the complexes was confirmed by their ¹¹⁹Sn NMR spectra that showed two triplet features for each complex, attributed to a mixture of the expected cis and trans isomers. The triplet signal is due to the coupling with two equivalent phosphorus atoms, consistent with an octahedral geometry around the tin center. In addition, density functional theory (DFT)/B3LYP calculations have been carried out to support the interpretations of NMR data. The results are discussed and compared with those reported for related complexes.

GRAPHICAL ABSTRACT      

Di-tert-butyl(N-pyrrolyl)phosphane,-sulfide, and-selenide, studied by multinuclear magnetic resonance

 Di-tert-butyl(N-pyrrolyl)phosphane (1),-sulfide (2) and-selenide (3) were studied by ¹H, ¹³C, ¹⁵N, ³¹P and ⁷⁷Se NMR spectroscopy in solution. Restricted rotation about the P–N bond was observed for 1 (ΔG^≠ _C≈58.5 kJ/mol) and 2, 3 (ΔG^≠ _C≈45 kJ/mol) by ¹H and ¹³C NMR at variable temperature. The fairly high pyrrolyl rotation barrier in 1 is ascribed to the expected steric effects exerted by the tert-butyl groups and to repulsion between the lone pairs of electrons at the phosphorus and nitrogen atoms. These repulsive forces are reduced in 2 or 3, or in di-tert-butyl(phenyl) phosphane (ΔG^≠ _C≈44 kJ/mol). Signs of coupling constants ⁿJ(³¹P, ¹³C) and ⁿ⁺¹J(³¹P, ¹H) (n=2, 3) were determined by two-dimensional (2D) ¹³C/¹H heteronuclear shift correlations. The preferred orientation of the pyrrolyl group in 1 is evident from the coupling constants ²J(³¹P, ¹³C(2))=+35.4 Hz and ²J(³¹P, ¹³C(5))=−9.3 Hz, typical of C(2) in syn and C(5) in anti position with respect to the assumed axis of the phosphorus lone pair. Hahn-echo extended (HEED) polarization transfer pulse sequences served for measuring ¹J(³¹P, ¹⁵N) and isotope induced chemical shifts ¹Δ^15/14N(³¹P) from ³¹P NMR spectra. Received: 4 April 1996/Revised: 6 May 1996/Accepted: 11 May 1996     

Di-tert-butyl(N-pyrrolyl)phosphane,-sulfide, and-selenide, studied by multinuclear magnetic resonance

 Di-tert-butyl(N-pyrrolyl)phosphane (1),-sulfide (2) and-selenide (3) were studied by ¹H, ¹³C, ¹⁵N, ³¹P and ⁷⁷Se NMR spectroscopy in solution. Restricted rotation about the P–N bond was observed for 1 (ΔG^≠ _C≈58.5 kJ/mol) and 2, 3 (ΔG^≠ _C≈45 kJ/mol) by ¹H and ¹³C NMR at variable temperature. The fairly high pyrrolyl rotation barrier in 1 is ascribed to the expected steric effects exerted by the tert-butyl groups and to repulsion between the lone pairs of electrons at the phosphorus and nitrogen atoms. These repulsive forces are reduced in 2 or 3, or in di-tert-butyl(phenyl) phosphane (ΔG^≠ _C≈44 kJ/mol). Signs of coupling constants ⁿJ(³¹P, ¹³C) and ⁿ⁺¹J(³¹P, ¹H) (n=2, 3) were determined by two-dimensional (2D) ¹³C/¹H heteronuclear shift correlations. The preferred orientation of the pyrrolyl group in 1 is evident from the coupling constants ²J(³¹P, ¹³C(2))=+35.4 Hz and ²J(³¹P, ¹³C(5))=−9.3 Hz, typical of C(2) in syn and C(5) in anti position with respect to the assumed axis of the phosphorus lone pair. Hahn-echo extended (HEED) polarization transfer pulse sequences served for measuring ¹J(³¹P, ¹⁵N) and isotope induced chemical shifts ¹Δ^15/14N(³¹P) from ³¹P NMR spectra. Received: 4 April 1996/Revised: 6 May 1996/Accepted: 11 May 1996     

Bis(Tetramethylselenophosphoramidoyl) Methylamine Complexes of Cd(Ii) and Zn(Ii): Synthesis and Multinuclear (31P, 77Se,and 113Cd) Nmr Characterization in Solution

Abstract

Five new complexes ZnL₂(ClO₄)₂ (1), CdL₂(ClO₄)₂ (2), CdL₂(BF₄)₂ (3), CdLCl₂ (4), and CdL(NO₃)₂ (5) [L = ((Me₂N)₂PSe)₂NMe] have been synthesized and characterized by elemental analysis, infrared (IR) and multinuclear (³¹P, ⁷⁷Se, and ¹¹³Cd), and nuclear magnetic resonance (NMR) spectroscopy. The ³¹P and ⁷⁷Se NMR data showed that the title ligand is coordinated in a bidentate fashion to the metal center via its both P=Se groups. The solution structure of the cadmium complexes was further confirmed by its ¹¹³Cd NMR spectra, which displayed a quintuplet for the perchlorate complex and a triplet for each of the nitrate and chloride complexes, respectively due to coupling with four (two ligands) and two (one ligand) equivalent phosphorus nuclei, consistent with a four-coordinate tetrahedral geometry for the cadmium center. The results are discussed and compared with the corresponding oxo and thio analogues.     

31P–31P SPIN-SPIN COUPLINGS IN SYMMETRICAL AND UNSYMMETRICAL DERIVATIVES OF P(NMeNMe)3P

Abstract

The syntheses and characterization of seven new unsymmetrical derivatives of the type YP(NMeNMe)₃PZ are reported. Where Y = O or NPh: Z = S, Se, Br⁺ and where Y = a lone pair, Z = Br⁺ Also reported are the new symmetrical derivatives where Y = Z = (OC)₅W or (OC)₃Ni and the new monovalent cage cations YP(NMeCH₂)₃CMe⁺ where Y = Ph₃C and Br. Conductivity and ³¹P nmr evidence for the formulation of the phosphonium cations is presented. ³J³¹P³¹P couplings, obtained directly from the ³¹P nmr spectra of the unsymmetrical derivatives, are found to rise upon successively oxidizing the phosphorus atoms, and a rationale is offered. This coupling is also extracted from the ¹⁸³W and ⁷⁷Se satellite peaks in the ³¹P spectra of the symmetrical derivatives where Y = Z = (OC)₅W and Se, respectively.

A self-consistent set of assignments of the ³¹P chemical shifts is arrived at for YP(NMeNMe)₃PZ compounds and the useful role of LIS reagents in analyzing their proton spectra is delineated. The ¹³C nmr spectral parameters of these derivatives are also presented.     

Synthesis and Characterization of New N-(Diphenylphosphino)-Naphthylamine Chalcogenides: X-Ray Structures of (1-NHC10H7)P(Se)Ph2 and Ph2P(S)OP(S)Ph2

Abstract

The reaction of 1-naphthylamine with one equivalent of chlorodiphenylphosphine in the presence of triethylamine gave the (1-NHC₁₀H₇)PPh₂ (1) ligand. Refluxing of 1 with elemental sulfur or grey selenium in toluene (1:1 molar ratio) afforded (1-NHC₁₀H₇)P(S)Ph₂ (2) and (1-NHC₁₀H₇)P(Se)Ph₂ (3), respectively. Moreover, the byproduct {Ph₂P(S)}₂O (4) was isolated from the reaction of 1 with elemental sulfur. Compounds 1–3 were identified and characterized by multinuclear (¹H, ¹³C, ³¹P, ⁷⁷Se) NMR spectroscopy, mass spectrometry, and elemental analysis. Crystal structure determinations of 3 and 4 were carried out.     

Spectroscopic characterization and <Emphasis Type="Italic">Ab initio</Emphasis> calculations of new diazaphosphole and diazaphosphorinane

Phosphoryl chloride is used as a starting material to synthesize new diazaphosphole, (1) and diazaphosphorinane, (2). The products are characterized by ¹H, ¹³C, ³¹P NMR, and IR spectroscopy. A high value ² J(PNH) = 17.0 Hz, 17.2 Hz is measured for two non-equivalent NH protons of endocyclic nitrogen atoms in compound 1, while it greatly decreases to 4.5 Hz in 2. Also, great amounts are obtained for two ² J(P,C) as well as two ³ J(P,C) in the ¹³C NMR spectrum of 1, but they are zero in 2. Here, the effect of ring strain and ring size on the structural and spectroscopic parameters is observed. The ³¹P NMR spectra reveal that δ(³¹P) of compound 1 is far much more downfield (12.63 ppm) relative to that of compound 2 (−10.39 ppm). Furthermore, ab initio quantum chemical calculations are performed to optimize the structures of these molecules by density functional theory (B3LYP) and Hartree-Fock (HF) methods, using the standard 6−31+G** basis set. The stabilization energies are calculated by the equation ΔE _{stabilization} = E _molecule − ΣE _i , where i = atom. To obtain the atomic hybridizations, NBO computations are made at the B3LYP/6−31+G** level. Also, by NMR calculations the ¹H, ¹³C, ³¹P chemical shifts are obtained and compared with the experimental ones.     

Correlated ab initio calculations of one-bond 31P?77Se and 31P?125Te spin–spin coupling constants in a series of PSe and PTe systems accounting for relativistic effects (part 2)

Synthetic chalcogen–phosphorus chemistry permanently makes new challenges to computational Nuclear Magnetic Resonance (NMR) spectroscopy, which has proven to be a powerful tool of structural analysis of chalcogen–phosphorus compounds. This paper reports on the calculations of one-bond ³¹P ⁷⁷Se and ³¹P ¹²⁵Te NMR spin–spin coupling constants (SSCCs) in the series of phosphine selenides and tellurides. The applicability of the combined computational approach to the one-bond ³¹P ⁷⁷Se and ³¹P ¹²⁵Te SSCCs, incorporating the composite nonrelativistic scheme, built of high-accuracy correlated SOPPA (CC2) and Coupled Cluster Single and Double (CCSD) methods and the Density Functional Theory (DFT) relativistic corrections (four-component level), was examined against the experiment and another scheme based on the four-component relativistic DFT method. A special J-oriented basis set (acv3z-J) for selenium and tellurium atoms, developed previously by the authors, was used throughout the NMR calculations in this work at the first time. The proposed computational methodologies (combined and ‘pure’) provided a reasonable accuracy for ³¹P ⁷⁷Se and ³¹P ¹²⁵Te SSCCs against experimental data, characterizing by the mean absolute percentage errors of about 4% and 1%, and 12% and 8% for selenium and tellurium species, respectively. The present study reports typical relativistic corrections to ⁷⁷Se ³¹P and ¹²⁵Te ³¹P SSCCs, calculated within the four-component DFT formalism for a broad series of tertiary phosphine selenides and tellurides with different substituents at phosphorus.     

Constituents of fruit pulp of <Emphasis Type="Italic">Maytenus salicifolia</Emphasis> and complete 1D/2D NMR data of 3<Emphasis Type="Italic">β</Emphasis>-hydroxy-D:B-friedo-olean-5-ene

A mixture of long-chain hydrocarbons constituted by nonacosane (29C, 7.5%), hentriacontane (31C, 48.3%), and tritriacontane (33C, 30.1%), the ester 1′-acetyloxymethylpentacosa-20′-enyl 10-hydroxydecanoate (2), β-amyrin (3), friedelin (4), and lupeol (5), and 3β-hydroxy-D:B-friedo-olean-5-ene (6) were identified as constituents of fruits of Maytenus salicifolia Reissek (Celastraceae). The structural formula and the stereochemistry of compound 6 were established by the data obtained through ¹H and ¹³C NMR spectroscopy, including DEPT-135 and 2D (HMQC, HMBC, and NOESY) experiments. By analysis of the spectral data, it was possible to correct seven chemical shift assignments of compound 6, which were erroneous attributed and published in the scientific literature.     

Palladium(II)-dppe-arylazoimidazole complexes: Synthesis,and spectroscopic characterization

Reaction of [Pd(dppe)Cl₂/Br₂] with AgOTf in a dichloromethane medium followed by ligand addition led to [Pd(dppe)(OSO₂CF₃)₂] and then [Pd(dppe)(RaaiR)](OSO₂CF₃)₂ [RaaiR′ = p-R-C₆H₄-N=N-C₃H₂-NN-1-R′, (1–3), abbreviated as a N,N′-chelator, where N(imidazole) and N(azo) are represented by N and N′, respectively; R = H (a), Me (b), Cl (c) and R′ = Me (1), CH₂CH₃ (2), CH₂Ph (3), OSO₂CF₃ is the triflate anion, dppe = 1,2-bis-(diphenylphosphinoethane)]. ³¹P “¹H” NMR confirmed that due to the two phosphorus atom interaction in the azoimine symmetrical environment one sharp peak was formed. The ¹H NMR spectral measurements suggest that azo-imine link with lot of phenyl protons in the aromatic region. ¹³C (¹H) NMR spectrum, ¹H, ¹H COSY and ¹H, ¹³C HMQC spectrum assign the solution structure and stereo-retentive conformation in each complex.     

Multinuclear NMR Studies of the Substitlent Effects in N-Phenyl-P,P,P-Triarylphospha-λ5-Azenes,Triaryl-Phosphines and Triarylphosphine Oxides

Abstract

A series of N-phenyl-P,P,P-triarylphospha-λ⁵-azenes (1) as well as their ^l5N labeled analogs was synthesized. The ¹³C, ³¹P, and ¹⁵N NMR spectra of this series and those of two other series of related compounds, namely triarylphosphines (2) and triarylphosphine oxides (3), were measured and are reported. Many satisfactory correlations using the mono-substituent parameter (MSP) and the Taft dual-substituent parameter (DSP) treatments with the ¹³C substituent chemical shifts (SCS), ³¹P SCS, ¹⁵N SCS and the one bond P-N, P-C and C-N coupling constants were observed and will be discussed. Thus, for example, the ³¹P and ¹⁵N chemical shifts in 1 correlated with [sgrave]^?with negative slopes while the ³¹P chemical shifts in 3 correlated with those in 1 with a slope of 2.0. The ¹³C chemical shifts in 1 correlated excellently with the corresponding ones in 3 with slopes very close to unity. The substituent effects on the chemical shifts of the various nuclei were shown to be mainly due to changes in the charge distribution on those nuclei. In 1 the one bond P-N and P-C coupling constants correlated with [sgrave]_p and [sgrave]_R respectively. The one bond P-C coupling constants of 1 correlated quite well with those of 3 with a slope of 0.93 while the corresponding correlation of 1 with 2 was quite poor. Taft DSP treatment of ¹J_PCin 1 and 3 were quite similar, ρI and ρR were both negative and ρR was much larger than ρI. Series 2 showed behavior which was different from that shown by 1 and 3 but similar to that shown by other systems with a lone electron pair on the atom bound to the phenyl ring. The substituent effects on the one bond P-N, P-C and C-N coupling constants will be discussed in terms of bonding and hybridization changes between the directly bonded nuclei.     

Is the 1 J PSe Coupling Constant a Reliable Probe for the Basicity of Phosphines? A 31P NMR Study

Abstract

The influence of different heteroaryl and functionalized aryl substituents on the electron-donating ability and basicity of the phosphorus atoms in heteroaryl phosphines and diphosphines has been determined by the use of the direct ¹J_PSe coupling constants of the corresponding selenides. The generality of the use of ³¹P–⁷⁷Se spin–spin coupling constants as probe for the basicity of phosphines is discussed as well as the scope and limits of this concept.

GRAPHICAL ABSTRACT      

Synthesis,characterization, structures,and DFT study of zinc(II) complexes with tributylphosphine chalcogenides

Four new zinc(II) complexes of the type [ZnCl₂(n-Bu₃PE)₂] (E=O (1), S (2), Se (3), or Te (4)) have been synthesized from zinc(II) chloride and the ligands n-Bu₃PE giving yields of 56–88%. The adducts were characterized by multinuclear (³¹P, ¹³C, and ⁷⁷Se) NMR, conductivity, IR spectroscopy and by X-ray analyses. Zinc complexes 1–4 are compriseS of two ligands coordinated to the metal center in a distorted tetrahedral arrangement. The P=E bond lengths of 1.497(7) (E=O), 2.000(4) (E=S), and 2.178(2) Å (E=Se) in these complexes are slightly elongated compared to those in the free ligand. In addition, a DFT/B3LYP theoretical study on the geometry optimization of the title ligands and their zinc complexes has been carried out in order to support and complement the experimental data and to further investigate the nature of the chalcogenide-metal interaction. The results show good agreement between the experimental and theoretical data.     

Nepetadiol,a new triterpenediol from <Emphasis Type="Italic">Nepeta suavis</Emphasis>

Nepetadiol, a new tetracyclic triterpene diol (1), was isolated from the chloroform-soluble portion of the whole plant of Nepeta suavis. In addition, lawsonin (2) and lawsonic acid (3) have been isolated for the first time from this species. The structures of the isolated compounds were based on ¹H and ¹³C NMR spectra, including two-dimensional NMR techniques like COSY, HMQC, and HMBC, and comparison with the literature data.     

31P Sold-State NMR Investigations on Phosphonic Acids and Phosphonates

Abstract

As known from ³¹P solid-state NMR investigations of inorganic phosphates there is a correlation between chemical shift anisotropy parameters and crystal lattice parameters. For phosphonic acids and phosphonates similar correlations are not known.     

15N, 31P,and 13C NMR Spectroscopy of N-Arylsulfonyl-and N-Arylcarbonyl-P,P,P-triphenylphospha-λ-Azenes. Substituent Effects and Electronic Structure

Abstract

The ¹⁵N, ³¹P and ³¹C NMR spectra of several series of phospha-λ⁵-azenes are reported. For the N-arylsulfonyl-P,P,P-triphenylphospha-δ⁵-azene series (R-C₆H₄N-SO₂-PPh₃), the ³¹P chemical shifts, various ¹³C chemical shifts and ¹J_PN were observed to correlate linearly with the Hammett σ constants. Interestingly, the ¹⁵N chemical shifts did not correlate acceptably with any σ or with the Taft dual substituent parameter equation, and 1J_PC was invariant with substituent. For the N-arylcarbonyl-P,P,P-triphenylphospha-λ⁵-azene series (R-C₆H₄-CO-N=PPh₃), δ_31P and various δ_13C's were observed to linearly correlate with the δ constants, while δ_15N, ¹J_PN and ¹J_PC correlated with both the σ and σ constants. For the N-phenyl-P,P,P-triarylphospha-λ⁵-azene series [Ph-N=P(C₆H₄-R)₃] the best correlations were observed between ³¹P, ¹⁵N and several ¹³C chemical shifts and the σ constants.     

THE ASSIGNMENT OF ACYCLIC STEREOISOMERS. 11. CONFORMATIONAL ANALYSIS OF 3-PHOSPHONYL-2- BENZOYLAMINOPROPIONIC ACID METHYL-ESTERS

Abstract

The conformational analysis of 3-phosphonyl-2-benzoylaminopropionic acid methyl esters, which occur as diastereomeric pairs of enantiomers owing to two present chiral centres, has been managed successfully by means of ³¹P, ¹³C, ¹H and ¹⁵N chemical shifts as well as the characteristically different coupling constants between the ¹H, ¹³C and ³¹P nuclei. In this light, the diastereomers involved could be assigned readily.     

1D to 3D NMR study of microporous alumino‐phosphate AlPO4‐40

From one‐ to two‐ and three‐dimensional MAS NMR solid‐state experiments involving ³¹P and ²⁷Al, we show that the structure of microporous alumino‐phosphate AlPO₄‐40 contains at least four times more sites than expected, and we attribute two types of Al_IV sites. The newly described ²⁷Al‐³¹P MQ‐HMQC opens new possibilities of describing details of three‐dimensional bounded networks. Copyright © 2009 John Wiley & Sons, Ltd.