e-journal

Deciphering the NMR Fingerprints of the Disordered System with Quantum Chemical Studies

---

Recent developments in solid-state NMR techniques helped acquire high-resolution NMR spectra for solid
systems with structural disorder. But the structural origin of the observed chemical shift nonequivalence in
these systems has not been revealed. We report a quantum chemical investigation of the solid-state NMR
spectrum in N,N-bis(diphenylphosphino)-N-((S)-R-methylbenzyl)amine, where eight nonequivalent 31P NMR
chemical shifts were resolved with a range of 13.0 ppm. Results from using different quantum chemical
methods, computational algorithms, intermolecular effects, and structures indicate that for the disordered
system, geometry optimization gives the best accord with experimental NMR chemical shifts, which has a
theory-versus-experiment correlation R2 = 0.949 and SD = 1.1 ppm, or R2 = 0.994 and SD = 0.4 ppm when
the average of two unassigned NMR shifts for each molecule is used. In addition, these calculations indicate
that the experimental chemical shift nonequivalence in this system is mainly a consequence of the different
geometries around the phosphorus atoms due to disordered environments. The experimental 31P NMR chemical
shifts are well correlated (R2 = 0.981) with two conformation angles and one bond length, each associated
with one of the three bonding interactions around the phosphorus atoms. These results will facilitate the use
of quantum chemical techniques in structural characterization of disordered solids and elucidation of NMR
properties.

---

Ketersediaan

Tidak ada salinan data

Informasi Detail

Judul Seri

J. Phys. Chem.

No. Panggil

-

Penerbit

Washington, DC : American Chemical Society., 2009

Deskripsi Fisik

J. Phys. Chem. A 2009, 113, 5993–5997

Bahasa

English

ISBN/ISSN

-

Klasifikasi

-

Tipe Isi

-

Tipe Media

-

Tipe Pembawa

-

Edisi

-

Subjek

KIMIA

Info Detail Spesifik

-

Pernyataan Tanggungjawab

agus

Versi lain/terkait

Lampiran Berkas

Komentar

---

Anda harus masuk sebelum memberikan komentar