Solid-state EPR strategies for the structural characterization of paramagnetic NO adducts of frustrated Lewis pairs (FLPs)

Autor(es)

de Oliveira, Jr., Marcos ^[1] ; Wiegand, Thomas ^[2] ; Elmer, Lisa-Maria ^[3] ; Sajid, Muhammad ^[3] ; Kehr, Gerald ^[3] ; Erker, Gerhard ^[3] ; Magon, Claudio Jose ^[1] ; Eckert, Hellmut ^{[4, 1]}

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Fis Sao Carlos, BR-13560970 Sao Paulo - Brazil

^[2] ETH, Lab Phy Chem, CH-8049 Zurich - Switzerland

^[3] WWU Munster, Inst Organ Chem, D-48149 Munster - Germany

^[4] WWU Munster, Inst Phys Chem, D-48149 Munster - Germany

• Tipo de documento: Artigo Científico
• Fonte: Journal of Chemical Physics; v. 142, n. 12 MAR 28 2015.
• Citações Web of Science: 9

Resumo

Anisotropic interactions present in three new nitroxide radicals prepared by N, N addition of NO to various borane-phosphane frustrated Lewis pairs (FLPs) have been characterized by continuous-wave (cw) and pulsed X-band EPR spectroscopies in solid FLP-hydroxylamine matrices at 100 K. Anisotropic g-tensor values and B-11, N-14, and P-31 hyperfine coupling tensor components have been extracted from continuous-wave lineshape analyses, electron spin echo envelope modulation (ESEEM), and hyperfine sublevel correlation spectroscopy (HYSCORE) experiments with the help of computer simulation techniques. Suitable fitting constraints are developed on the basis of density functional theory (DFT) calculations. These calculations reveal that different from the situation in standard nitroxide radicals (TEMPO), the g-tensors are non-coincident with any of the nuclear hyperfine interaction tensors. The determination of these interaction parameters turns out to be successful, as the cw- and pulse EPR experiments are highly complementary in informational content. While the continuous-wave lineshape is largely influenced by the anisotropic hyperfine coupling to 14N and 31P, the ESEEM and HYSCORE spectra contain important information about the 11B hyperfine coupling and nuclear electric quadrupolar interaction. The set of cw- and pulsed EPR experiments, with fitting constraints developed by DFT calculations, defines an efficient strategy for the structural analysis of paramagnetic FLP adducts. (c) 2015 AIP Publishing LLC. (AU)

• Processo FAPESP: 13/07793-6 - CEPIV - Centro de Ensino, Pesquisa e Inovação em Vidros
• Beneficiário: Edgar Dutra Zanotto
• Modalidade de apoio: Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs
• Processo FAPESP: 13/23490-3 - Técnicas de ressonância magnética empregadas no estudo da correlação estrutura/propriedades em vidros e vitrocerâmicas fotônicos
• Beneficiário: Marcos de Oliveira Junior
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado