Synthesis and structural study of some new phosphorus(v) hydrazide compounds: spectroscopic evidence and a theoretical approach

Abstract

New phosphorus(V) hydrazide compounds containing the [-P(O)NHNHC(O)OR] fragment have beenprepared by the reaction of mono-and di-chloro phosphoryl intermediates with methyl (R = CH 3 , 1-5) and tert-butyl (R = C(CH 3 ) 3 , 6-9) carbazates, and characterized by IR and multinuclear NMR spectroscopy.Molecular structures of 1, 2, and 5 have been established by X-ray diffraction analysis to investigate the relative orientation of the present moieties, resulting hydrogen bonding motifs and stabilizing intermolecular interactions. The impact of the intermolecular contacts on crystal packing has been further studied by Hirshfeld surface analysis. The dependence of experimental d 31 P and 2 J PNH values on phosphorus substituents has been explored using natural bond orbital (NBO) analysis. Likewise, the reasons for maintaining the tetrahedral geometry around the phosphorus atom in the synthesized compounds and not rearranging to a trigonal bipyramidal one (in comparison with spirophosphoranes) have been investigated theoretically. Overall, the NBO results reveal the influential role of electronic delocalization and s-content in hybridization for the above-mentioned experimental evidence.

On the roles of close shell interactions in the structure of acyl-substituted hydrazones: An experimental and theoretical approach

“…% Transmitance The Natural Bond Orbital (NBO) population analysis allow for the calculations of donor acceptor interactions estimated by the second order perturbation theory [20]. In particular, the electrostatic contribution for "classical" C=O···H-N hydrogen bonds [48], can be associated with the partial transfer of a lone pair of electrons of the oxygen atom to the N-H antibonding orbital [49,50]. Such a hyperconjugative interaction can operate between remote orbitals determinaning the conformational landscape of simple molecules [51,52], as well as the backbone conformation of peptides [53].…”