187Os subspectra in 1H and 31P{1H} spectra of triosmium carbonyl clusters

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.     

1H and 13C NMR study of α-acetylenic PIII and PIV derivatives. Signs and magnitudes of J(P?C) and J(P?H)

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 P^IV 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 P^III 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.     

1H and 31P nuclear magnetic resonance spectra of compounds containing the PIII?N?PV skeleton

The ¹H and ³¹P NMR spectra of a series of compounds containing the P^III-N-P^V skeleton including Cl₂PNMeP(Z)Cl₂ (Z?O or S), Cl₂P·NMe·P(O)CINMe₂, P₄(NMe)₆Z_n (Z?S, n = 1?3; Z?Se, n = 1), XP(NBu^t)₂P(Z)X (X?Cl, Z?O or S; X?OMe, Z?S or Se; X?NMe₂, Z?S or Se; X?NEt₂, Z?Se), (X?O or S), and Ph₂PNRP(S)Ph₂ (R?Me, Et) have been obtained. ¹H-{³¹P} double resonance, and in selected cases, ³¹P-{¹H, ⁷⁷Se} and ³¹P-{¹H, ³¹P} triple resonance experiments, indicate that ²J(P^III NP^V) is positive in acyclic compounds, negative in most cyclic or cage compounds, and furthermore, is related to the conformation adopted by the P^III-N bond.     

31P-NMR-Daten heterocyclischer phosphine. Diastereomerenzuordnung an 1,3-Oxa-, 1,3-Aza- und 1,3-thiaphospholanen

The diastereomers of 16 1,3-oxa-, 1,3-aza- and 1,3- thiaphospholanes were assigned by means of the coupling constants ²J(P? C? H) and ³J(P? C? CH₃) and the linewidths of the ³¹P signals and ¹H chemical shifts of CH₃ groups. It is shown that the change in the ³¹P chemical shifts allows the estimation of the relative configuration in these compounds.     

Etude des Signes des Constantes de Couplage 3J(P?X?C?H) et 4J(F?P?X?C?H) dans les Diaza-, Dioxa- et Dithiaphospholanes Fluores

The NMR spectra of the trivalent fluorophospholanes ( 1, 2, 3 ) have been analysed at length. The absolute signs of the ³J(P? H) and ⁴J(F? H) coupling constants have been referred to the known negative sign of the ¹J(P? F) coupling constant from selective heteronuclear double resonance experiments. The ³J(P? O? C? H) and ³J(P? N? C? H) coupling are positive. The weak values observed for ³J(P? S? C? H) have opposite signs, the larger being positive. All the ⁴J(F? P? X? C? H) coupling constants are positive showing a lack of stereospecificity.     

Dérivés Alléniques du Phosphore. Influence de l'État de Coordination du Phosphore et de la Nature des Radicaux Liés au Phosphore sur les Signes de J(P?H)

The signs of the phosphorus-proton coupling constants in various allenic organophosphorus compounds have been determined by either analysis of the AB₂X spectra or double resonance. Probable absolute signs have been obtained by taking ³J(P? H) as positive. In allenic phosphine oxides, the following signs are obtained: ²J(P? H) +ve, ³J(P? H) +ve, ⁴J(P? H) ?ve, ⁵J(P? H) +ve and the ⁴J(P? H) coupling constant varies mostly with the inductive effect of the substituents bound to the phosphorus atom. In allenic phosphines, these sings are: ²J(P? H) +ve, ³J(P? H) +ve, ⁴J(P? H) ?ve and +ve and the ⁴J(P? H) coupling constant varies with both the inductive and resonance effects to the substituents. This coupling constant is negative except when the phosphorus atom is bound to groups which are electron-donating by resonance effects. These results are discussed in relation to the pπ? dπ bonding in phosphine.     

Substituent effects on nuclear spin–spin carbon–carbon coupling constants in derivatives of acetylene

¹J(¹³C?¹³C) nuclear spin–spin coupling constants in derivatives of acetylene have been measured from natural abundance ¹³C NMR spectra and in one case (triethylsilyllithiumacetylene) from the ¹³C NMR spectrum of a ¹³C-enriched sample. It has been found that the magnitude of J(C?C) depends on the electronegativity of the substituents at the triple bond. The equation ¹J(¹³C?¹³C) = 43.38 E_x + 17.33 has been derived for one particular series of the compounds Alk₃SiC?CX, where X denotes Li, R₃Sn, R₃Si, R₃C, I, Br or Cl. The ¹J(C?C) values found in this work cover a range from 56.8 Hz (in Et₃SiC?Li) to 216.0 Hz (in PhC?CCI). However, the ¹J(C?C) vs E_x equation combined with the Egli–von Philipsborn relationship allows the calculation of the coupling constants in Li₂C₂ (32 Hz) and in F₂C₂ (356 Hz). These are probably the lowest and the highest values, respectively, which can be attained for ¹J(CC) across a triple bond. The unusually large changes of the ¹J(C?C) values are explained in terms of substituent effects followed by a re-hybridization of the carbons involved in the triple bond. INDO FPT calculations performed for two series of acetylene derivatives, with substituents varied along the first row of the Periodic Table, corroborate the conclusions drawn from the experimental data.     

Determination Rapide de la Configuration Cis Trans des Alcenes CH?CHCH? Utilisation des Complexes de Terres Rares

In Z? CH? CH?CH? Y compounds (Z or Y being an alkyl group) the ethylenic part of the spectra is often very complex and the ³J(H? C?C? H) coupling constant which is a good tool for determining the configuration, is not easily determined. We have studied such allylic derivatives and many configurations have been assigned through stereospecific synthesis. Except a very few cases, δ CH(Z) of the cis isomer is larger than δ CHZ of the trans isomer. In alcohols RCH?CH? CHOHR′ the stereoisomers behave differently in solutions with europium, praseodymium, holmium and dysprosium complexes. The spectra of the trans isomers remain strongly coupled but ³J(H? C?C? H) becomes easy to measure in the cis compounds.     

13C NMR spectra of phosphole–P(IV) dimers; ABX and AA′X 13C?31P coupling in some derived structures

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.     

Nuclear magnetic resonance spectroscopy. Analysis of the 1H and 13C spectra of Br13CH213CH2Br

The ¹H and ¹³C NMR spectra of 1,2-dibromoethane-¹³C₂ have been analyzed to determine the magnitude (38·9 Hz) and sign (positive) of ¹J(C? C) relative to those of ³J(H? H) (positive). This type of coupling appears to be rather insensitive to the presence of bromine or methyl as substituents on the carbons.     

Heterocycles Contenant du Phosphore—V. Analyse des Spectres de Resonance Magnetique Protonique des Oxo-2 Methoxy ou Phénoxy-2, Methyl-3, Oxazaphospholanes-1,3,2: Exemples de Spectres du type ABXY

The ³¹P decoupled PMR spectra of the title oxazaphospholanes give rise to well resolved ABXY patterns. Among the eight possible solutions, six can be readily eliminated from chemical shifts considerations and the choice between the remaining two is based on tickling experiments. Good fits are observed between experimental and calculated spectra. The relative signs of the ³J(P? O? C? H) and ³J(P? N? C? H) coupling constants are given by tickling and Indor experiments. The ring conformation is discussed.     

3J(PCNH) in phosphorus substituted thioformamides as a configurational probe

Coupling between P and (N)? H has been observed in the ¹H{¹⁴N}NMR spectra of a series of phosphorus substituted thioformamides, R¹₂/P(X)C(S)NHR². For R² = H one of the two couplings constants ³J(PCNH) is much larger than the other. The larger constant is assumed to be ³J(PCNH) (trans) and the magnitude of ³J(PCNH) for several compounds with R² = Me or Ph is used to assign the configuration about the C(S)? N bond.     

13C n.m.r. spectroscopy of diethyl alkyl- and benzyl-phosphonates. A study of phosphorus–carbon spin–spin coupling constants over one to seven bonds

¹³C chemical shifts and ³¹P? ¹³C spin–spin coupling constants are reported for 10 alkyl-, 20 benzyl- and 3 (naphthylmethyl)-phosphonates. While in saturated aliphatic chains P–C couplings over more than four bonds cannot be resolved, couplings over up to seven bonds are observed in the benzyl type systems. Conformational and substituent effects on J(PC) are studied and discussed. ⁿJ(PF) (n = 4, 5, 6) are reported for the isomeric (fluorobenzyl)phosphonates and ⁿJ(PP) (n = 5, 6, 7) were obtained from the ¹³C satellites in the ³¹P n.m.r. spectra of the isomeric diphosphonates, C₆H₄[CH₂P(O)(OEt)₂]₂. Comparison of those ¹³C absorptions of the latter, which represent the X parts of ABX or AA′X spin systems, with the spectra of the corresponding (methylbenzyl)phosphonates, CH₃C₆H₄CH₂P(O)(OEt)₂, yielded the relative signs of ⁿJ(PC) (n = 2–6).     

Multiple magnetic resonance studies of some para-substituted derivatives of triphenyl phosphine

¹⁹F and ³¹P decoupling experiments are used to simplify the proton spectra of para-substituted derivatives of triphenyl phosphine, prior to ¹H-{¹H} tickling experiments. ³J(³¹P…?H) and ⁴J(³¹P…?H) are positive, and ⁵J(³¹P…?¹⁹F) is negative in the trivalent phosphorus derivatives, and all become more positive as the valency of the phosphorus atom is increased. A triple resonance experiment is used to show that ⁷J(³¹P…?H) in [p-CH₃C₆H₄CH₂P^⊕(C₆H₅)₃] is negative. The double resonance technique is used to relate the ³¹P chemical shifts to the tetramethylsilane resonant frequency.     

An Investigation of 1:1 Adducts of Gallium Trihalides with Triarylphosphines by Solid‐State 69/71Ga and 31P NMR Spectroscopy

Several 1:1 adducts of gallium trihalides with triarylphosphines, X₃Ga(PR₃) (X=Cl, Br, and I; PR₃=triarylphosphine ligand), were investigated by using solid‐state ^69/71Ga and ³¹P NMR spectroscopy at different magnetic‐field strengths. The ^69/71Ga nuclear quadrupolar coupling parameters, as well as the gallium and phosphorus magnetic shielding tensors, were determined. The magnitude of the ⁷¹Ga quadrupolar coupling constants (C_Q(⁷¹Ga)) range from approximately 0.9 to 11.0 MHz . The spans of the gallium magnetic shielding tensors for these complexes, δ₁₁?δ₃₃, range from approximately 30 to 380 ppm; those determined for phosphorus range from 10 to 40 ppm. For any given phosphine ligand, the gallium nuclei are most shielded for X=I and least shielded for X=Cl, a trend previously observed for In^III–phosphine complexes. This experimental trend, attributed to spin‐orbit effects of the halogen ligands, is reproduced by DFT calculations. The signs of C_Q(^69/71Ga) for some of the adducts were determined from the analysis of the ³¹P NMR spectra acquired with magic angle spinning (MAS). The ¹J(^69/71Ga,³¹P) and ΔJ(^69/71Ga, ³¹P) values, as well as their signs, were also determined; values of ¹J(⁷¹Ga,³¹P) range from approximately 380 to 1590 Hz. Values of ¹J(^69/71Ga,³¹P) and ΔJ(^69/71Ga,³¹P) calculated by using DFT have comparable magnitudes and generally reproduce experimental trends. Both the Fermi‐contact and spin‐dipolar Fermi‐contact mechanisms make important contributions to the ¹J(^69/71Ga,³¹P) tensors. The ³¹P NMR spectra of several adducts in solution, obtained as a function of temperature, are contrasted with those obtained in the solid state. Finally, to complement the analysis of NMR spectra for these adducts, single‐crystal X‐ray diffraction data for Br₃Ga[P(p‐Anis)₃] and I₃Ga[P(p‐Anis)₃] were obtained.     

Synthesis of Enantiomerically Pure 1,5,5‐Trideuterated cis‐ and trans‐2,4‐Dioxa‐3‐phosphadecalins. 31P‐NMR Evidence of Covalent‐Bond Formation and the Stereochemical Implications in the Course of the Inhibition of δ‐Chymotrypsin

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.     

Structural studies on aryl‐substituted enaminoketones and their thio analogues. Part II. Experimental and DFT calculated carbon–carbon coupling constants,nJ(CC)'s (n = 1–3)

Spin–spin carbon–carbon coupling constants across one, two and three bonds, J(CC), have been measured for a series of aryl‐substituted Z‐s‐Z‐s‐E enaminoketones and their thio analogues. As a result, a large set, altogether 178, of J(CC)s has been obtained. It consists of 82 couplings across one bond, 31 couplings across two bonds and 65 couplings across three bonds. Independently, the DFT calculations at the B3PW91/6‐311++G(d,p)//B3PW91/6‐311++G(d,p) level yielded a set of theoretical J(CC) values. A comparison of these two sets of data gave an excellent linear correlation with parameters a and b close to ideal; a = 0.9978 which is not far from unity and b = 0.22 Hz which is close to zero. The ¹J(CC) couplings determined for the crucial fragment of the molecules, i.e. ? C?C? C?O (or ? C?C? C?S), are: ¹J(C?C) ≈ 68 Hz (67 Hz) and ¹J(C? C) = 60.5 Hz (60.0 Hz). The corresponding couplings found for the Z‐s‐Z‐s‐E isomer of the parent enaminoketone, 4‐methylamino‐but‐3‐en‐2‐one are 64.1 and 59.3 Hz, respectively. The most sensitive towards substitution of the oxygen atom by sulfur are two‐bond couplings between the α‐vinylic and aromatic C_ipso carbon atoms, which attain 12 Hz in the enaminoketone derivatives and decrease to 5 Hz in their thio analogues. Copyright © 2009 John Wiley & Sons, Ltd.     

Multinuclear NMR Studies and Spin System Analyses on Dibenzo[c.e][1,2]Oxaphosphorine 2‐Oxides

2H‐Dibenzo[c.e][1,2]oxaphosphorine 2‐oxide (HDOPO), 2‐(N,N‐diethylamino)‐dibenzo[c.e][1,2]oxaphosphorine 2‐oxide (DEADOPO), and 2‐ethoxy‐dibenzo[c.e][1,2]oxaphosphorine 2‐oxide (EtODOPO) are fully characterized in CDCl₃ by ¹H, ¹³C, ³¹P, and ¹⁵N NMR spectroscopy on 800‐ and 500‐MHz instruments. A strategy enabling their unambiguous signal assignment is presented, with special emphasis on 2D ¹H,¹³C HMBC spectra. Additional line‐shape iterations of the aromatic ¹H multiplets (ABCDX and ABCDEX spin systems) provided all long‐range ⁿJ_H,H and ⁿJ_P,H coupling constants with utmost precision. The experimental results augmented with those of the model compound phenylphosphonous acid clearly demonstrate that ⁿJ_H,H couplings of the PH proton as well as the ⁿJ_P,C values do not decrease in a monotonic manner with the number of intervening bonds from the phosphorus atom. This fact may potentially lead signal misassignments, if the analysis starts out from the coupling constants, as it occurred for HDOPO in the recent publication by Wagner et al. (Phosphorus, Sulfur and Silicon, 187, 2012, 781–798). The corrected assignment will be given in the present paper. Finally, the A₂M₃X or ABM₃X type ¹H spectral patterns of ethyl groups are also analyzed and explicit equations are derived to evaluate the strongly coupled ABM₃X multiplets in EtODOPO.     

The synthesis,NMR (1H, 13C, 119Sn) and IR spectral studies of some di‐ and tri‐organotin(IV) sulfonates: X‐ray crystal structure of [(n‐C4H9)2Sn(OSO2C6H4CH3‐4)2·2H2O]

A number of alkyltin(IV) paratoluenesulfonates, R_nSn(OSO₂C₆H₄CH₃‐4)_4?n (n = 2, 3; R = C₂H₅, n‐C₃H₇, n‐C₄H₉), have been prepared and IR spectra and solution NMR (¹H, ¹³C, ¹¹⁹Sn) are reported for these compounds, including (n‐C₄H₉)₂Sn(OSO₂X)₂ (X = CH₃ and CF₃), the NMR spectra of which have not been reported previously. From the chemical shift δ(¹¹⁹Sn) and the coupling constants ¹J(¹³C, ¹¹⁹Sn) and ²J(¹H, ¹¹⁹Sn), the coordination of the tin atom and the geometry of its coordination sphere in solutions of these compounds is suggested. IR spectra of the compounds are very similar to that observed for the paratoluenesulfonate anion in its sodium salt. The studies indicate that diorganotin(IV) paratoluenesulfonates, and the previously reported compounds (n‐C₄H₉)₂Sn(OSO₂X)₂ (X = CH₃ and CF₃), contain bridging SO₃X groups that yield polymeric structures with hexacoordination around tin and contain non‐linear C? Sn? C bonds. In triorganotin(IV) sulfonates, pentacoordination for tin with a planar SnC₃ skeleton and bidentate bridging paratoluenesulfonate anionic groups are suggested by IR and NMR spectral studies. The X‐ray structure shows [(n‐C₄H₉)₂Sn(OSO₂C₆H₄CH₃‐4)₂·2H₂O] to be monomeric containing six‐coordinate tin and crystallizes from methanol–chloroform in monoclinic space group C2/c. The Sn? O (paratoluenesulfonate) bond distance (2.26(2) Å) is indicative of a relatively high degree of ionic character in the metal–anion bonds. Copyright © 2003 John Wiley & Sons, Ltd.     

Characterization of five [C4H7O]+ Ion structures. Fragmentation of the 2-pentanone molecular ion

The [C₄H₇0]⁺ ions [CH₂?CH? C(?OH)CH₃]⁺ (1), [CH₃CH?CH? C(?OH)H]⁺ (2), [CH₂?C(CH₃)C(?OH)H]⁺ (3), [Ch₃CH₂CH₂C?O]⁺ (4) and [(CH₃)₂CHC?O]⁺ (5) have been characterized by their collision-induced dissociation (CID) mass spectra and charge stripping mass spectra. The ions 1–3 were prepared by gas phase protonation of the relevant carbonyl compounds while 4 and 5 were prepared by dissociative electron impact ionization of the appropriate carbonyl compounds. Only 2 and 3 give similar spectra and are difficult to distinguish from each other; the remaining ions can be readily characterized by either their CID mass spectra or their charge stripping mass spectra. The 2-pentanone molecular ion fragments by loss of the C(1) methyl and the C(5) methyl in the ratio 60:40 for metastable ions; at higher internal energies loss of the C(1) methyl becomes more favoured. Metastable ion characteristics, CID mass spectra and charge stripping mass spectra all show that loss of the C(1) methyl leads to formation of the acyl ion 4, while loss of the C(5) methyl leads to formation of protonated vinyl methyl ketone (1). These results are in agreement with the previously proposed potential energy diagram for the [C₅H₁₀O]⁺˙ system.