Exploring the forces that control the P-C bond length in phosphamides and their complexes: The key role of hyperconjugation
Περίληψη
Τύπος
Είδος δημοσίευσης σε συνέδριο
Είδος περιοδικού
peer reviewed
Είδος εκπαιδευτικού υλικού
Όνομα συνεδρίου
Όνομα περιοδικού
Organometallics
Όνομα βιβλίου
Σειρά βιβλίου
Έκδοση βιβλίου
Συμπληρωματικός/δευτερεύων τίτλος
Περιγραφή
The factors tuning the R(P-C) bond length of the labile P-C bond in phosphamides have been explored by means of density functional theory, employing natural bond orbital (NBO) analysis. The second-order perturbation stabilization energy Delta E(2) due to hyperconjugation accounts well for the unusually long R(P-C) bond lengths in a series of phosphamides and related species. Favorable n(O) -> sigma*(P-C) interactions primarily affect the R(P-C) bond length through electron delocalization. Deleting these interactions from our calculations results in significant shortening of the P-C bond, to a bond length close to that of the P-C(sp(2)) bonds. This holds also true if n(O) is "screened" by protonation, while n(P) does not affect the strength of the P-C bond. Moreover, the linear correlations of R(P-C) vs Delta E(2) and of R(P-C) vs Delta E-del substantiate the validity of the concept that hyperconjugative interactions tune the P-C bond length in phosphamides and provide a novel explanation of P-C bond lability. It was found that the combination of electron- withdrawing substituents on the carbonyl C atom with electron- releasing substituents on the P atom strengthen the P-C bond, thus stabilizing phosphamides. Phosphamides could also be stabilized by coordination with early-transition-metal ions (e.g. [CpTiCl2{kappa O-1-H2PC(O)Me}](+)) but are destabilized upon coordination with late-transition-metal ions (e.g. [Ag{kappa O-1-MeC(O)PH2}](+) and [Cu{kappa P-2,O-MeC(O)PH2}](+)). The coordination of phosphamides with Rh(III) in [CpRhCl2{kappa P-1-H2PC-(OH)CH3}](+) only marginally affects the R(P-C) bond length. Finally, the interaction of phosphamides with the hard Li+, K+, and Tl+ cations does not affect significantly the n(O) -> sigma*(P-C) hyperconjugative interactions, and therefore, the R(P-C) bond length is only slightly shortened.
Περιγραφή
Λέξεις-κλειδιά
hydroformylation, phosphine, chemistry, catalysts, density
Θεματική κατηγορία
Παραπομπή
Σύνδεσμος
<Go to ISI>://000237592800014
http://pubs.acs.org/doi/abs/10.1021/om0600137
http://pubs.acs.org/doi/abs/10.1021/om0600137
Γλώσσα
en
Εκδίδον τμήμα/τομέας
Όνομα επιβλέποντος
Εξεταστική επιτροπή
Γενική Περιγραφή / Σχόλια
Ίδρυμα και Σχολή/Τμήμα του υποβάλλοντος
Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας