Me2N Group Research Articles

Effect on chair-chair equilibrium of 3-substituted-1,3,2-oxazaphosphorinanes of replacement of Me2N substituent on phosphorus by isoPr2N

The chair-chair conformational equilibria (A ⇌ B) f a series of 1,3,2-dioxaphosphorinanes featuring three-coordinated phosphorus substituted with an isoPr2N group (1–6) have been studied by 1H NMR spectroscopy. Substituents at N(3) included Ph, Me, and isoPr. Compared to the analogous series with an Me2N group on phosphorus, 1–6 populate the chair conformation B with R2N equatorial to a greater extent. This is interpreted to mean that conformer A is more destabilized by the greater steric size of isoPr2N than is conformer B. Thus, the repulsive interactions between equatorial Me2N and the substituent on N3, believed to be responsible for depopulation of B that results in an unexpectedly high population of A with Me2N on phosphorus, is overcome by destabilization of A by the axial isoPr2N. The apparent size effect of substituents on N3 in destabilization of B follows the order Ph > isoPr > Me, as observed earlier for the series with a Me2N group on phosphorus. © 1996 John Wiley & Sons, Inc.

Das 2-Halogen-5,6-benzo-1,3,2-dioxaphosphorinan-4-on-Ringsystem / The 2-Halogeno-5,6-benzo-1,3,2-dioxaphosphorinan-4-one Ring System

The reaction of salicylic acid with phosphorus trichloride furnished the previously known 2-chloro-5,6-benzo-1,3,2-dioxaphosphorinan-4-one heterocycle 1 which was unambiguously characterized, for the first time, by NMR spectroscopy and mass spectrometry. The fluorine and bromine analogues of 1, 2 and 3 were synthesized from 1, using exchange reactions. The iodo derivative, 4, owing to its instability, could be identified only in the reaction mixture by 1H and 31P NMR spectroscopy. The amine derivatives 5-8 were obtained from 1 using standard exchange reactions, either with silylated amines or with secondary amines in the presence of base. There was no evidence by 1H NMR spectroscopy for intramolecular Me2N→P coordination in 6. The 31P NMR investigation of 7 revealed the presence of two rotational isomers, presumably as a result of steric hindrance at the P–N bond by the methyl substituent of the piperidine group. The reaction of 6 with methyl iodide led to methylation at the nitrogen atom of the Me2N group, producing the ammonium iodide, 9. The reactions of 5,6 and 8 with norbornadiene tetracarbonyl molybdenum failed to furnish isolable products.

Unusual formation of a λ 6P‐tetrafluorophosphate involving intramolecular donor–acceptor interaction; x‐ray crystal structure analysis and temperature‐dependent NMR‐spectra

AbstractThe N,N,N′‐trimethylethylenediaminetetrafluorophosphate, 4, was formed in the unusual reaction of N,N,N′‐trimethyl‐N′‐trimethylsilylethylenediamine, 1, with the NP‐bonded tetrafluorophosphoranes, dimethylaminotetrafluorophosphorane, 2, or morpholinotetrafluorophosphorane, 3. There was no evidence for the cleavage of a PF bond in the tetrafluorophosphoranes (with formation of Me3SiF); instead, the SiN compounds, R2NSiMe3 (R2 = Me2 or O(CH2CH2)2) were formed. The 19F and 31P NMR spectra of 4 at room temperature indicated dynamic behavior. The X‐ray crystal structure analysis of 4 revealed the presence of a five‐membered ring, formally as a result of intramolecular donor–acceptor interaction (PN = 196.5 pm) between the nitrogen atom of the Me2N group and phosphorus.

Structure of 4-(dimethylamino)pyridine cyanoborane adduct

C7H~oNa.BHaCN, Mr = 161.0, monoclinic, 12/a, a = 13.773 (4), b = 9.635 (3), c = 14.430 (3) ~, fl = 99.67 (2) °, V = 1888 (2) A 3, Z = 8, Dx = 1-13 gcm -3, a(Mo Ka) =0.71073/~, /z = 0.7 cm -l, F(000)=688, 294K. Final R=0.047 for 809 observed reflections. The non-hydrogen atoms in the (dimethylamino)pyridine residue are essentially co- planar; the nitrogen atom (N7) of the Me2N group has sp 2 hybridization. There is substantial localized double bonding involving N7 and the pyridine ring. The N 1--BH2CN section of the molecule has N 1--B 1.574(4), B--C 1-573(5), C--N 1-130 (4) A, N1--B---C 109.4 (3), B--C--N 178-2 (3) °. Introduction. There is considerable current interest in amine adducts of cyanoboranes as precursors to boron-containing analogues of amino acids (Spielvogel, Ahmed, Silvey, Wisian-Neilson &

INTRAMOLECULAR DONOR-ACCEPTOR-INTERACTION INN,N,N′-TRIMETHYL-N′-HALOPHOSPHINOETHYLENDIAMINES AND INN,N,N′-TRIMETHYL-N′-DIFLUOROARSINOETHYLENDIAMINE

Abstract The reaction of Me2NCH2CH2N(Me)SiMe3 with MePCl2, ButPCl2 and AsF3 was found to proceed with formation of the trimethylsilyl halides, Me3SiX (X=Cl, F), and of the phosphorus-nitrogen (or arsenic-nitrogen)-bonded compounds, Me2NCH2CH2N(Me)P(Me)Cl, Me2NCH2CH2N(Me)P(But)Cl, and Me2NCH2CH2N(Me)AsF2, respectively. When PBr3, Et2NPCl2, and Et2NPBr2 were allowed to react with Me2NCH2CH2N(Me)SiMe3 the ionic, intramolecularly coordinated compounds, [Me2NCH2CH2N(Me)PBr]+Br−, [Me2NCH2CH2N(Me)PNEt2]+Cl, and [Me2NCH2CH2N(Me)PNET2]+ Br− were formed. The high- and low-temperature 1H- and 19F-n.m.r. spectra of these compounds were investigated. Their interaction with Lewis acids has been shown in the case of some acyclic, covalent phosphorylated derivatives of N.N.N′-trimethyl-ethylendiamine to induce intramolecular complexation between phosphorus and the nitrogen of the Me2N group. The spiro compound, [(Me2NCH2CH2N(Me))2P]+[BPh4]−, was obtained from the monocyclic product, [Me2NCH2CH2N(Me)PCl]+ Cl−, with Na[BPh...

13C and 31P NMR studies of some aminophosphonium chlorides

AbstractThe multinuclear NMR spectral data for an homologous series of tertiary phosphines, R3‐nP(NMe2)n, aminophos‐phonium ions, [R3PNR′R″]+, and phosphonium ions, [R4‐nPMe]+, where R = Me, Et, n‐Pr and Ph, R′ and/or R″ = H, Me and n = 0 and 1 are reported and discussed. Quaternization by alkylation or chloramination causes an increase in the 31P chemical shift (Δ δP is positive), a decrease in the 13C chemical shift (Δ δC is negative) for all carbons, an increase in the magnitudes of 1J(PC), 3J(PC), 3J(PNCH) and 2J(PCH) and a decrease in the magnitude of 2J(PC). Substitution of a Me2N group for an alkyl or aryl group produces an increase in the 31P chemical shift and in the magnitude of 1J(PC). α‐ and β‐deshielding and γ‐shielding effects are noted in the 13C NMR spectra and β‐deshielding and γ‐shielding effects are noted in the 31P NMR spectra with substitution on the phosphorus and nitrogen atoms.

Influence of Ionic and Polar Solutes upon ΔG≠ and ΔV≠ of the Amide Rotation in Aqueous Solutions of Dimethylacetamide

As a probe for changes in hydrate structure one can use the pressure‐dependence of the activation volume ΔV≠ for rotation of the Me2N group in dimethyl acetamide (DMA). In dilute solutions ΔV≠ for DMA is practically pressure‐independent, but is increased by ionic solutes. This could indicate an open hydrate sheath in which the rotation can take place without the water molecules in the surroundings being re‐ordered.

Phosphinohydrazines. Part IV. Coordination compounds of N,N-dimethyl,N′-diphenylphosphinohydrazine and N,N-dimethyl-N′-diphenylthiophosphinatohydrazine

A study of complexes of (a) N,N-dimethyl,N′-diphenylphosphinohydrazine, DPH, viz., Pd(DPH)Cl2, Pd(DPH)2Cl2, [Pd(DPH)2Cl]ClO4, Pt(DPH)2Cl2, Pt(DPH)Cl4, Hg(DPH)Cl2; (b) N,N-dimethyl,N´-diphenylthiophosphinatohydrazine, DPS, viz., Pd(DPS)Cl2, Pt(DPS)Cl4, Ag(DPS)NO3, Zn(DPS)Cl2, Cd(DPS)Cl2, and Hg(DPS)Cl2, and (c) N,N-dimethylhydrazine, DMH, viz., Zn(DMH)2Cl2 and Cd(DMH)Cl2, has been carried out using conductivity, molecular weight, infrared, and nuclear magnetic resonance measurements. DPH functions mostly as a unidentate ligand, with the phosphorus atom as the preferred donor site. Thus Pd(DPH)Cl2 is a chlorobridged dimer in solution in weakly polar solvents, while the monomeric form in polar solvents is of uncertain structure. A trans, four-coordinate structure is consistent for Pd(DPH)2Cl2. For [Pd(DPH)2Cl]ClO4, however, one DPH ligand is chelating through the phosphorus and terminal nitrogen atoms, while the second ligand is unidentate; the compound is a monomeric uni–univalent electrolyte in nitrobenzene. The ligand DPS appears to chelate via the sulfur and central nitrogen atoms, giving four-membered ring structures; a cis configuration is suggested for Pd(DPS)Cl2. Zn(DMH)2Cl2 is monomeric in solution, with the Me2N group coordinated to the metal.

THE INFRARED SPECTRA OF ORGANO-PHOSPHORUS COMPOUNDS: II. THE 1–2.6 μ REGION

The application of near infrared spectra to the study of phosphorus compounds has been investigated. It has been found that each type of radical gives a characteristic set of bands, which are not appreciably affected by changes in the molecule more than two atoms distant. Characteristic group frequencies are given for MeO, EtO, n-PrO, i-PrO, n-BuO, Me, Et, Me2N, Et2N, and i-Pr2N groups attached to phosphorus. Only the MeP bands are noticeably altered by the nature of the substitution on the phosphorus atom. Qualitative predictions of the spectra of compounds containing more than one type of C—H group may be made by summing the contributions of the components.