Karplus-Type Equations for 1J(X−Y) in Molecules HmX−YHn:  (X, Y = N, O, P, S)

Bene, Janet E. Del; Elguero, José

doi:10.1021/jp066503u

Cited by 11 publications

(9 citation statements)

References 27 publications

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“…It is noteworthy that the NMR spectroscopic parameters of 19 are remarkably distinct from those reported for 2a , b . , Importantly, the absolute value of the 1 J (P A P A′ ) coupling constant in 19 (137.0 Hz) is distinctly smaller than the corresponding coupling constants observed for 2a , b ( a : 1 J (P A P A′ ) = 669 Hz; b : 1 J (P A P A′ ) = 467.5 Hz). This small coupling constant is in agreement with the substantially smaller sum of the bond angles (Σ) on the P A atoms of 19 (Σ = 286.6°) compared to the corresponding parameter of compounds 2a , b ( 2a : Σ = 347.2°; 2b : Σ = 327.1°) and, furthermore, indicates a predominantly antiperiplanar arrangement of the lone pairs of electrons on P A and P A′ in 19 in solution …”

Section: Resultssupporting

confidence: 80%

P–N/P–P Bond Metathesis for the Synthesis of Complex Polyphosphanes

Feldmann

Weigand

2012

J. Am. Chem. Soc.

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A unique hexaphosphane featuring a 2,2'-bi(1,2,3-triphosphacyclopentane) moiety (19) and an ethylene-bridged bis-isotetraphosphane (27(c,m)) were both selectively prepared in efficient one-pot syntheses from easily accessible tris(3,5-dimethyl-1-pyrazolyl)phosphane (14) and 1,2-bis(phenylphosphanyl)ethane (18(c,m)). The formation of 27(c,m) is an example of a highly efficient P-P bond formation via protolysis. In contrast, the formation of 19 comprises P-N/P-P bond metathesis steps. This constitutes a novel synthetic approach toward the preparation of complex polyphosphanes. Detailed spectroscopic investigations form the basis for a mechanistic understanding of this unprecedented methodology. Furthermore, the preparation of a unique dinuclear iron-carbonyl complex which features hexaphosphane 19 as a bridging ligand illustrates the potential use of complex polyphosphanes such as 19 as ligands in transition metal chemistry.

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Section: Resultssupporting

confidence: 80%

P–N/P–P Bond Metathesis for the Synthesis of Complex Polyphosphanes

Feldmann

Weigand

2012

J. Am. Chem. Soc.

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“…1p J (N–P) for the pnicogen complexes can be compared to 1 J (N–P) for the H 2 P–NH 2 molecule. A previous study of one-bond coupling constants in molecules H m X–YH n including H 2 P–NH 2 found that 1 J (X–Y) is extremely sensitive to rotation around the X–Y bond . This can also be seen from the values of 1 J (N–P) and their components in Table for the equilibrium C 1 structure of H 2 P–NH 2 and for an optimized C s trans structure.…”

Section: Resultsmentioning

confidence: 71%

“…A previous study of onebond coupling constants in molecules H m XÀYH n including H 2 PÀNH 2 found that 1 J(XÀY) is extremely sensitive to rotation around the XÀY bond. 36 This can also be seen from the values of 1 J(NÀP) and their components in Table 5 for the equilibrium C 1 structure of H 2 PÀNH 2 and for an optimized C s trans structure. The largest component of 1 J(NÀP) for the trans structure is a positive FC term, followed by smaller negative PSO and SD terms.…”

Section: Articlementioning

confidence: 65%

Structures, Energies, Bonding, and NMR Properties of Pnicogen Complexes H₂XP:NXH₂(X ═ H, CH₃, NH₂, OH, F, Cl)

et al. 2011

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Ab initio calculations have been carried out in a systematic investigation of P···N pnicogen complexes H(2)XP:NXH(2) for X ═ H, CH(3), NH(2), OH, F, and Cl, as well as selected complexes with different substituents X bonded to P and N. Binding energies for complexes H(2)XP:NXH(2) range from 8 to 27 kJ mol(-1) and increase to 39 kJ mol(-1) for H(2)FP:N(CH(3))H(2). Equilibrium structures have a nearly linear A-P-N arrangement, with A being the atom directly bonded to P. Binding energies correlate with intermolecular N-P distances as well as with bonding parameters obtained from AIM and SAPT analyses. Complexation increases (31)P chemical shieldings in complexes with binding energies greater than 19 kJ mol(-1). One-bond spin-spin coupling constants (1p)J(N-P) across the pnicogen interaction exhibit a quadratic dependence on the N-P distance for complexes H(2)XP:NXH(2), similar to the dependence of (2h)J(X-Y) on the X-Y distance for complexes with X-H···Y hydrogen bonds. However, when the mixed complexes H(2)XP:NX'H(2) are included, the curvature of the trendline changes and the good correlation between (1p)J(N-P) and the N-P distance is lost.

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“…In an EOM-CCSD study of H m X-YH n where X and Y are N, O, P or S, a Karplus-type dependence of 1 J XY on the dihedral angle was observed [232]. It was found that the presence of one or more electron pairs on X and Y determines the variation of 1 J XY with the dihedral angle.…”

Section: Conformational Studiesmentioning

confidence: 98%