Indirectly detected heteronuclear correlation solid-state NMR spectroscopy of naturally abundant 15N nuclei

Althaus, Stacey M.; Mao, Kanmi; Stringer, John A.; Kobayashi, Takeshi; Pruski, Marek

doi:10.1016/j.ssnmr.2013.11.001

Cited by 56 publications

(88 citation statements)

References 51 publications

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“…Figure 4B). 57 In agreement with the DNP-based experiment, the idHetcor measurement showed a dominant correlation between the 1 H NMR signal at ∼2.4 ppm and NMe 2 groups resonating at around −355 ppm. A minor peak at −370 ppm most likely represents small concentration of free HNMe 2 left within the pores.…”

Section: ■ Results and Discussionsupporting

confidence: 80%

Mesoporous Silica-Supported Amidozirconium-Catalyzed Carbonyl Hydroboration

et al. 2015

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The hydroboration of aldehydes and ketones using a silica-supported zirconium catalyst is reported. Reaction of Zr(NMe2)4 and mesoporous silica nanoparticles (MSN) provides the catalytic material Zr(NMe2)n@MSN. Exhaustive characterization of Zr(NMe2)n@MSN with solid-state (SS)NMR and infrared spectroscopy, as well as through reactivity studies, suggests its surface structure is primarily ≡SiOZr(NMe2)3. The presence of these nitrogen-containing zirconium sites is supported by 15N NMR spectroscopy, including natural abundance 15N NMR measurements using dynamic nuclear polarization (DNP) SSNMR. The Zr(NMe2)n@MSN material reacts with pinacolborane (HBpin) to provide Me2NBpin and the material ZrH/Bpin@MSN that is composed of interacting surface-bonded zirconium hydride and surface-bonded borane ≡SiOBpin moieties in an approximately 1:1 ratio, as well as zirconium sites coordinated by dimethylamine. The ZrH/Bpin@MSN is characterized by 1H/2H and 11B SSNMR and infrared spectroscopy and through its reactivity with D2. The zirconium hydride material or the zirconium amide precursor Zr(NMe2)n@MSN catalyzes the selective hydroboration of aldehydes and ketones with HBpin in the presence of functional groups that are often reduced under hydroboration conditions or are sensitive to metal hydrides, including olefins, alkynes, nitro groups, halides, and ethers. Remarkably, this catalytic material may be recycled without loss of activity at least eight times, and air-exposed materials are catalytically active. Thus, these supported zirconium centers are robust catalytic sites for carbonyl reduction and that surface-supported, catalytically reactive zirconium hydride may be generated from zirconium-amide or zirconium alkoxide sites. ABSTRACT: The hydroboration of aldehydes and ketones using a silica-supported zirconium catalyst is reported. Reaction of Zr(NMe 2 ) 4 and mesoporous silica nanoparticles (MSN) provides the catalytic material Zr(NMe 2 ) n @MSN. Exhaustive characterization of Zr(NMe 2 ) n @MSN with solidstate (SS)NMR and infrared spectroscopy, as well as through reactivity studies, suggests its surface structure is primarily  SiOZr(NMe 2 ) 3 . The presence of these nitrogen-containing zirconium sites is supported by 15 N NMR spectroscopy, including natural abundance 15

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Section: ■ Results and Discussionsupporting

confidence: 80%

Mesoporous Silica-Supported Amidozirconium-Catalyzed Carbonyl Hydroboration

et al. 2015

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“…12)). 1 H-13 C correlations can be measured in a few minutes for some favorable cases and 1 H-15 N correlations can be a few hours to overnight measurements in natural abundance samples 69 . A few attempts in the past have been made to use CRAMPS in order to achieve 1 H inverse detection at moderate MAS rate 18,70 .…”

Section: Sensitivitymentioning

confidence: 99%

Fast magic-angle sample spinning solid-state NMR at 60–100 kHz for natural abundance samples

Nishiyama

2016

Solid State Nuclear Magnetic Resonance

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“…out under fast MAS at a rate of νrot = 40 kHz using the idHETCOR pulse sequence shown in Figure S5 and described in detail in earlier studies. 54 In short, the experiment commenced with 1 H  15 N CP transfer, followed by a t1 period during which 15 (Tables S4 and S5, respectively).…”

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confidence: 99%

Natural abundance ¹⁴N and ¹⁵N solid-state NMR of pharmaceuticals and their polymorphs

Veinberg

Johnston

Jaroszewicz

et al. 2016

Phys. Chem. Chem. Phys.

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Indirectly detected heteronuclear correlation solid-state NMR spectroscopy of naturally abundant 15N nuclei

Cited by 56 publications

References 51 publications

Mesoporous Silica-Supported Amidozirconium-Catalyzed Carbonyl Hydroboration

Mesoporous Silica-Supported Amidozirconium-Catalyzed Carbonyl Hydroboration

Fast magic-angle sample spinning solid-state NMR at 60–100 kHz for natural abundance samples

Natural abundance ¹⁴N and ¹⁵N solid-state NMR of pharmaceuticals and their polymorphs

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Indirectly detected heteronuclear correlation solid-state NMR spectroscopy of naturally abundant 15N nuclei

Cited by 56 publications

References 51 publications

Mesoporous Silica-Supported Amidozirconium-Catalyzed Carbonyl Hydroboration

Mesoporous Silica-Supported Amidozirconium-Catalyzed Carbonyl Hydroboration

Fast magic-angle sample spinning solid-state NMR at 60–100 kHz for natural abundance samples

Natural abundance 14N and 15N solid-state NMR of pharmaceuticals and their polymorphs

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Natural abundance ¹⁴N and ¹⁵N solid-state NMR of pharmaceuticals and their polymorphs