51 V NMR Spectroscopy and Ring-Size Effects on Catalytic Oxidative Alcohol Dehydrogenation in {V(O)(μ 2 –O)(pin F )} n Oligomers

Previously published (NMe4)2[V2(O)2(μ2-O)2(pinF)2], (NMe4)2[2], has been shown to aerobically catalyze the oxidation of benzylic and allylic alcohols under mild conditions. Herein, we report syntheses of [V3(O)3(μ2-O)3(pinF)3]3- trimers, which are also active in OAD catalysis. Trimer formation requires an ammonium cation with at least two hydrogen atoms per cation (e.g., H2NR2+ or H3NR+ but not HNR3+). The trimers (H2pip)3[V3(O)3(μ2-O)3(pinF)3], (H2pip)3[3], and (H3NAd)3[V3(O)3(μ2-O)3(pinF)3], (H3NAd)3[3], are reported herein along with the dimer (HNEt3)2[V2(O)2(μ2-O)2(pinF)2], (HNEt3)2[2]. Trimer formation is nearly quantitative with NH4+, H3NR+, and H2NR2+ salts, whereas HNR3+ and NR4+ salts did not result in trimer formation, as studied by 51V NMR. Monomer (NMe4)[V(O)2(pinF)(DMAP)], (NMe4)[1-DMAP], was also prepared to understand solution speciation. OAD catalysis of benzyl alcohol to benzaldehyde by trimers (H3NAd)3[3] and (NH4)3[3], formed in situ, is slower than (NMe4)2[2]; however, (H3NAd)3[3] is more robust to degradation than (NMe4)2[2] and (NH4)3[3]. The difference may correspond to the geometric differences in the {V(O)(μ2-O)}n rings that give rise to distinct reaction thermodynamics and kinetics. The stoichiometric reaction of (H3NAd)3[3] with 9-fluorenol results in net HAT and the formation of mixed-valent (H3NAd)3[V3(O)3(μ2-OH)(μ2-O)2(pinF)3], (H3NAd)3[5a] containing one V(4+) and two V(5+) centers. SCXRD characterization for trimers (H2pip)3[3], (H3NAd)3[V3(O)3(μ2-O)3(pinF)3], (H3NAd)3[3], (H3NAd)3[V3(O)3(μ2-OH)(μ2-O)2(pinF)3], (H3NAd)3[5a], dimer (HNEt3)2[V2(O)2(μ2-O)2(pinF)2], (HNEt3)2[2], and monomer (NMe4)[V(O)2(pinF)(DMAP)], (NMe4)[1-DMAP], are reported herein.

Authors

Douglas Fraser (ORCID: https://orcid.org/0000-0001-5313-1483)
Arnold L. Rheingold (ORCID: https://orcid.org/0000-0003-4472-8127)
Linda H. Doerrer (ORCID: https://orcid.org/0000-0002-2437-6374)
Aaron B. Beeler (ORCID: https://orcid.org/0000-0002-2447-0651)
Jessica K. Elinburg (ORCID: https://orcid.org/0000-0003-3064-3771)
Geoffrey Spencer
Jeffrey W. Bacon (ORCID: https://orcid.org/0000-0002-5206-3762)
Shawn M. Moore (ORCID: https://orcid.org/0000-0001-7752-4564)
John E. Cerritelli (ORCID: https://orcid.org/0009-0006-6945-3667)
Caroline S. M. Sabanos
Maggie I. Kitt

Institutions

Boston University (US)
University of California San Diego (US)

Publication Details

Journal: Inorganic Chemistry
Published: 2025-09-09
DOI: https://doi.org/10.1021/acs.inorgchem.5c02333
Citations: 1
Primary Topic: Catalysis and Oxidation Reactions
Type: article
Field-Weighted Citation Impact: 0.39

<sup>51</sup> V NMR Spectroscopy and Ring-Size Effects on Catalytic Oxidative Alcohol Dehydrogenation in {V(O)(μ <sub>2</sub> –O)(pin <sup>F</sup> )} <sub>n</sub> Oligomers

Authors

Institutions

Publication Details

⁵¹ V NMR Spectroscopy and Ring-Size Effects on Catalytic Oxidative Alcohol Dehydrogenation in {V(O)(μ ₂ –O)(pin ^F )} _n Oligomers

⁵¹ V NMR Spectroscopy and Ring-Size Effects on Catalytic Oxidative Alcohol Dehydrogenation in {V(O)(μ ₂ –O)(pin ^F )} _n Oligomers

Abstract

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