Conformational analysis and stereochemical dependences of ³¹P–¹H spin–spin coupling constants of bis(2‐phenethyl)vinylphosphine and related phosphine chalcogenides

Abstract

Theoretical energy-based conformational analysis of bis(2-phenethyl)vinylphosphine and related phosphine oxide, sulfide and selenide synthesized from available secondary phosphine chalcogenides and vinyl sulfoxides is performed at the MP2/6-311G** level to study stereochemical behavior of their (31)P-(1)H spin-spin coupling constants measured experimentally and calculated at different levels of theory. All four title compounds are shown to exist in the equilibrium mixture of two conformers: major planar s-cis and minor orthogonal ones, while (31)P-(1) H spin-spin coupling constants under study are found to demonstrate marked stereochemical dependences with respect to the geometry of the coupling pathways, and to the internal rotation of the vinyl group around the P(X)-C bonds (X = LP, O, S and Se), opening a new guide in the conformational studies of unsaturated phosphines and phosphine chalcogenides.

Trivinylphosphine and trivinylphosphine chalcogenides: stereochemical trends of 31P1H spin-spin coupling constants

“…It follows that a very good agreement is achieved between all experimental and conformationally averaged calculated couplings in 1-4 with the exception of 2 J(P,H X ) in 3 and 4, the latter being underestimated by 4-5 Hz, in line with our previous results. [1] The same underestimation (i.e. giving less positive/more negative values) of geminal couplings of the other types within the SOPPA approach has also been found for proton-proton, carbon-proton and carbon-carbon coupling constants.…”

“…The title trivinylphosphine (1) and three related trivinylphosphine chalcogenides (2-4) were synthesized by the known methods. [7] Thus, trivinylphosphine (1) was obtained by the Grignard method using vinylmagnesium bromide and PCl 3 .…”

“…[7] Thus, trivinylphosphine (1) was obtained by the Grignard method using vinylmagnesium bromide and PCl 3 . [7a] Further oxidation of 1 by elemental S or Se led to trivinylphosphine sulfide (3) and trivinylphosphine selenide (4), respectively, [7b] as shown in Scheme 2.…”

“…In continuation of our previous study [1] of the stereochemical behavior of 31 P-1 H spin-spin coupling constants in monovinylphosphines and monovinylphosphine chalcogenides by means of second-order polarization propagator approach (SOPPA) calculations in comparison with experiment, we now report our further results for the series of the newly synthesized trivinylphosphine (1) and three related phosphine chalcogenides -trivinylphosphine oxide (2), sulfide (3) and selenide (4) -providing even more interesting and complicated conformational behavior (Scheme 1).…”

“…[11] The correlation consistent triple-zeta-contracted basis set augmented with tight s-functions and optimized for calculation of spin-spin coupling constants, aug-cc-pVTZ-J, originally proposed by Sauer et al [12] was used in all calculations of 31 P-1 H spin-spin coupling constants. It is this level of theory, namely SOPPA/augcc-pVTZ-J, which demonstrated very high performance in the calculations of spin-spin coupling constants, and those involving phosphorus nuclei in particular, as shown recently in our previous publication [1] where a number of methods and basis sets have been examined to evaluate the best combination. It is well known that standard energy-optimized basis sets are in general not flexible enough to represent the operators involved in the calculation of indirect nuclear spin-spin coupling constants correctly, and augcc-pVTZ-J basis set was designated to account for these effects.…”