Double-resonance¹⁷O NMR experiments reveal unique configurational information for surface organometallic complexes

Abstract

Obtaining three-dimensional (3D) configurational information of surface organometallic complexes is a persistent challenge due to the low spatial sensitivity of most spectroscopic methods. We show that employing 17O-enriched supports enables...

On the use of NMR distance measurements for assessing surface site homogeneity

“…Solid-state NMR All solid-state NMR experiments were carried out using a 400 MHz/264 GHz Bruker MAS-DNP spectrometer equipped with an AVANCE III console and a 3.2 mm probe. The probe was tuned in a double-resonance configuration and a REDOR box was used to split the channel into two, such that 1 H- 13 C- 27 Al triple-resonance experiments could be performed. 26 Samples were impregnated with a 16 mM solution of TEKPol 27 in dry perdeuterated 1,1,2,2-tetrachloroethane (TCE-d2), 28,29 packed into sapphire rotors in an Ar glovebox, and spun at an MAS rate of 10 kHz.…”

“…26 Samples were impregnated with a 16 mM solution of TEKPol 27 in dry perdeuterated 1,1,2,2-tetrachloroethane (TCE-d2), 28,29 packed into sapphire rotors in an Ar glovebox, and spun at an MAS rate of 10 kHz. Hyperpolarized 1 H magnetization was excited using a 2.5 μs 90°pulse and transferred to 13 C using 1 ms of cross-polarization (CP). 13 C- 27 Al dipolar interactions were reintroduced using REDOR recoupling 18 with 8 μs 13 C inversion pulses.…”

“…Hyperpolarized 1 H magnetization was excited using a 2.5 μs 90°pulse and transferred to 13 C using 1 ms of cross-polarization (CP). 13 C- 27 Al dipolar interactions were reintroduced using REDOR recoupling 18 with 8 μs 13 C inversion pulses. A 150 μs, 100 kHz, 27 Al saturation pulse was applied to prevent the refocusing of dipolar interactions in the rotational-echo saturation-pulse double-resonance (RESPDOR) experiments.…”

“…8,9 The latter strategy has been applied to a growing number of supported metal complexes and has made use of surface 17 O, 27 Al, 29 Si, 133 Cs, and 207 Pb nuclei. [8][9][10][11][12][13][14] Recently, Jabbour et al have applied the strategy introduced by Berruyer et al to study the surface structure of an Ir NHC complex. 11 Using a 13 C-labelled NHC, they could detect the simultaneous presence of free and coordinated ligands, and a 13 C- 13 C correlation experiment also showed the existence of surface Ir centers coordinated to two NHC ligands.…”

“…[8][9][10][11][12][13][14] Recently, Jabbour et al have applied the strategy introduced by Berruyer et al to study the surface structure of an Ir NHC complex. 11 Using a 13 C-labelled NHC, they could detect the simultaneous presence of free and coordinated ligands, and a 13 C- 13 C correlation experiment also showed the existence of surface Ir centers coordinated to two NHC ligands. A similar observation was later made on an analogous Pt complex.…”