Tetranuclear Zirconium and Hafnium Polyhydride Complexes Composed of the “CpMH<sub>2</sub>” Units

Hu, Shaowei; Shima, Takanori; Luo, Yi; Hou, Zhaomin

doi:10.1021/om400012a

Cited by 19 publications

(15 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Theopold and co-workers previously reported the C 5 Me 5 - and C 5 Me 4 Et-ligated chromium polyhydride complexes [(C 5 Me 4 R)Cr(μ-H)] 4 (R = Me, Et) , and [{(C 5 Me 4 Et)Cr} 4 (μ-H) 5 (μ 3 -H) 2 ], which showed no activity for N 2 . We previously found that the sterically demanding C 5 Me 4 SiMe 3 group can serve as a unique supporting ligand for a wide range of rare-earth (group 3 and lanthanide) − and group 4 multimetallic polyhydride complexes. , In particular, the C 5 Me 4 SiMe 3 -ligated trinuclear titanium polyhydride complex [(C 5 Me 4 SiMe 3 Ti) 3 (μ 3 -H)(μ-H) 6 ] exhibits an extremely high activity for the activation of some very stable chemical bonds, such as splitting N 2 and aromatic rings − at ambient temperature. These findings have provoked our interest in exploring later transition-metal hydride complexes bearing the C 5 Me 4 SiMe 3 ligands.…”

Section: Introductionmentioning

confidence: 99%

“…We previously found that the sterically demanding C 5 Me 4 SiMe 3 group can serve as a unique supporting ligand for a wide range of rare-earth (group 3 and lanthanide) 71−73 and group 4 multimetallic polyhydride complexes. 48,74 In particular, the C 5 Me 4 SiMe 3 -ligated trinuclear titanium polyhydride complex [(C 5 Me 4 SiMe 3 Ti) 3 (μ 3 -H)(μ-H) 6 ] exhibits an extremely high activity for the activation of some very stable chemical bonds, such as splitting N 2 48 and aromatic rings 75−77 (2) in 95% yield (Scheme 1). In contrast, when the reaction was carried out in a concentrated solution (0.2 M) or without a solvent under a higher pressure of H 2 (10 atm), the trinuclear mixed-valence Cr(II)/Cr(III) tetrahydride complex [(Cp′Cr) 3 (μ 3 -H)(μ-H) 3 ] (3) was formed exclusively (89%).…”

Section: ■ Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Dinitrogen Activation and Hydrogenation by C₅Me₄SiMe₃-Ligated Di- and Trinuclear Chromium Hydride Complexes

et al. 2020

Self Cite

View full text Add to dashboard Cite

Activation of dinitrogen (N2) by well-defined metal hydrides is of much interest and importance, but studies in this area have remained limited to date. We report here N2 activation and hydrogenation by C5Me4SiMe3-ligated di- and trinuclear chromium polyhydride complexes. Hydrogenolysis of [Cp′Cr(μ-Me)2CrCp′] (Cp′ = C5Me4SiMe3) (1) with H2 in a dilute hexane solution under N2-free conditions affords the dichromium dihydride complex [Cp′Cr(μ-H)2CrCp′] (2), while hydrogenolysis of 1 in a concentrated solution or without solvent provides the trinuclear chromium tetrahydride complex [(Cp′Cr)3(μ3-H)(μ-H)3] (3). When the reaction is carried out in the presence of N2 in a dilute hexane solution, the tetranuclear diimide/dihydride complex [(Cp′Cr)4(μ3-NH)2(μ3-H)2] (4) is formed via N–N bond cleavage and N–H bond formation. The reaction of 2 with N2 at room temperature gives the tetranuclear imide/nitride/dihydride complex [(Cp′Cr)3(C5Me3(CH2)SiMe3)Cr(μ3-NH)(μ3-N)(μ-H)2] (5) via N2 cleavage and hydrogenation and C–H bond activation of a Cp methyl group. At –30 °C, the reaction of 2 with N2 affords the dinitride intermediate [(Cp′Cr)4(μ3-N)2(μ3-H)2] (6), which is quantitatively transformed to 5 at room temperature. Complex 5 reversibly converts to the stereoisomer 5′. The hydrogenation of a mixture of 5 and 5′ with H2 affords 4. The reaction of 3 with N2 proceeds at 100 °C to afford [(Cp′Cr)3(μ3-NH)2] (7). This transformation has also been investigated by DFT calculations. Both experimental and computational studies suggest that N2 incorporation into the chromium hydride cluster is involved in the rate-determining step. This work represents the first example of N2 cleavage and hydrogenation by well-defined chromium hydride complexes.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Dinitrogen Activation and Hydrogenation by C₅Me₄SiMe₃-Ligated Di- and Trinuclear Chromium Hydride Complexes

et al. 2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…The story of GRRM will be continued. Applications to excited states and photochemical processes,35,53,170 and also to various aspects of chemical reactions have been in progress 171–179. Developments in computational technologies extend the area of GRRM.…”

Section: Epiloguementioning

confidence: 99%

Study of Potential Energy Surfaces towards Global Reaction Route Mapping

Ohno

2016

The Chemical Record

View full text Add to dashboard Cite

The potential energy surface (PES) is just a theoretical construct based on the Born-Oppenheimer approximation, but it underlies various phenomena, including molecular vibrations, collisional ionizations, and chemical reactions. This account describes how a new idea for global reaction route mapping (GRRM), which had seemed to be impossible for chemical systems with more than three atoms, was born and has been developed during the course of the study of the PES. GRRM has pioneered new fields of chemistry. Furthermore, techniques for GRRM are still developing, and GRRM is further extending its application to various areas of chemistry and chemical physics.

show abstract

“…As part of our research project on understanding of the synergistic effects of multimetallics, we previously reported computational studies of the structure and reactivity of a series of multinuclear rare-earth and transition-metal complexes, − including the activation of dinitrogen (N 2 ) by the titanium hydride cluster 1 . In this paper, we wish to report the DFT studies of the reaction of benzene with the trinuclear titanium hydride cluster 1 (Figure b) .…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Insights into Ring Cleavage and Contraction of Benzene over a Titanium Hydride Cluster

Kang

Luo

et al. 2016

J. Am. Chem. Soc.

Self Cite

View full text Add to dashboard Cite

Carbon-carbon bond cleavage of benzene by transition metals is of great fundamental interest and practical importance, as this transformation is involved in the production of fuels and other important chemicals in the industrial hydrocracking of naphtha on solid catalysts. Although this transformation is thought to rely on cooperation of multiple metal sites, molecular-level information on the reaction mechanism has remained scarce to date. Here, we report the DFT studies of the ring cleavage and contraction of benzene by a molecular trinuclear titanium hydride cluster. Our studies suggest that the reaction is initiated by benzene coordination, followed by H2 release, C6H6 hydrometalation, repeated C-C and C-H bond cleavage and formation to give a MeC5H4 unit, and insertion of a Ti atom into the MeC5H4 unit with release of H2 to give a metallacycle product. The C-C bond cleavage and ring contraction of toluene can also occur in a similar fashion, though some details are different due to the presence of the methyl substituent. Obviously, the facile release of H2 from the metal hydride cluster to provide electrons and to alter the charge population at the metal centers, in combination with the flexible metal-hydride connections and dynamic redox behavior of the trimetallic framework, has enabled this unusual transformation to occur. This work has not only provided unprecedented insights into the activation and transformation of benzene over a multimetallic framework but it may also offer help in the design of new molecular catalysts for the activation and transformation of inactive aromatics.

show abstract

Tetranuclear Zirconium and Hafnium Polyhydride Complexes Composed of the “CpMH₂” Units

Cited by 19 publications

References 54 publications

Dinitrogen Activation and Hydrogenation by C₅Me₄SiMe₃-Ligated Di- and Trinuclear Chromium Hydride Complexes

Dinitrogen Activation and Hydrogenation by C₅Me₄SiMe₃-Ligated Di- and Trinuclear Chromium Hydride Complexes

Study of Potential Energy Surfaces towards Global Reaction Route Mapping

Mechanistic Insights into Ring Cleavage and Contraction of Benzene over a Titanium Hydride Cluster

Contact Info

Product

Resources

About

Tetranuclear Zirconium and Hafnium Polyhydride Complexes Composed of the “CpMH2” Units

Cited by 19 publications

References 54 publications

Dinitrogen Activation and Hydrogenation by C5Me4SiMe3-Ligated Di- and Trinuclear Chromium Hydride Complexes

Dinitrogen Activation and Hydrogenation by C5Me4SiMe3-Ligated Di- and Trinuclear Chromium Hydride Complexes

Study of Potential Energy Surfaces towards Global Reaction Route Mapping

Mechanistic Insights into Ring Cleavage and Contraction of Benzene over a Titanium Hydride Cluster

Contact Info

Product

Resources

About

Tetranuclear Zirconium and Hafnium Polyhydride Complexes Composed of the “CpMH₂” Units

Dinitrogen Activation and Hydrogenation by C₅Me₄SiMe₃-Ligated Di- and Trinuclear Chromium Hydride Complexes

Dinitrogen Activation and Hydrogenation by C₅Me₄SiMe₃-Ligated Di- and Trinuclear Chromium Hydride Complexes