Theoretical study of absorption spectrum of dirhodium tetracarboxylate complex [Rh2(CH3COO)4(H2O)2] in aqueous solution revisited

Kataoka, Yosuke; Kitagawa, Yasutaka; Saitô, Tôru; Nakanishi, Yoshito; Sato, Konomi; Miyazaki, Yuhei; Kawakami, Takashi; Okumura, Mitsutaka; Mori, Wasuke; Yamaguchi, Kizashi

doi:10.1080/10610278.2010.534553

Cited by 7 publications

(3 citation statements)

References 17 publications

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“…After considerable debate, [26] the so-called A band at the lowest energy, which is highly sensitive to the identity of the axial ligands, [18c,27] was ultimately assigned as the d(π*, Rh 2 )!d(σ*, Rh 2 ) excitation. [27][28] As such, better σ-donors and/or π-acceptors will increase the HOMO-LUMO gap and hence shift this band to higher energy. The second band, usually referred to as the B band, is largely invariant to axial ligand modifications and is due to a transition from the same RhÀ Rh dπ* orbitals to orbitals that are σ-antibonding with respect to the RhÀ O bonds of the equatorial carboxylate donors (d(π*, Rh 2 )!d(σ*, RhÀ O)).…”

Section: Spectroscopic Studiesmentioning

confidence: 99%

Synthesis and crystal structures of rhodium acetate paddle‐wheel complexes with anchor group‐functionalised and hydrogen bond‐supported axial ligands

Winter

Mang

Linseis

2022

Zeitschrift anorg allge chemie

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We report the synthesis and X‐ray structures of four Rh2(OAc)4(LAx)2 (OAc=acetate, CH3COO−) paddle‐wheel complexes (C1−C4) with methylthio‐modified axial ligands LAx derived from benzamidine (L1), anilinopyrimidine (L2) or isothiourea (L3, L4) that are capable of forming N−H⋅⋅⋅O hydrogen bonds to the equatorially bridging acetate ligands. This was done with the aim to suppress dissociation of the axial ligands and to make the complexes amenable to single‐molecule conductance measurements in a scanning tunneling microscope break‐junction (STM‐BJ) setup. The characteristic spectroscopic features (NMR, IR, vis), crystal structures, the hydrogen‐bonding motifs and a DFT‐based screening of their frontier molecular orbitals are presented. Our calculations suggest that hydrogen‐bonding stabilises axial ligand binding by 15 kJ/mol to 30 kJ/mol and that the HOMO of the rhodium paddle‐wheels is closer to the Au work function than the LUMO, so that the rhodium paddle‐wheels are expected to constitute hole conductors.

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Section: Spectroscopic Studiesmentioning

confidence: 99%

Synthesis and crystal structures of rhodium acetate paddle‐wheel complexes with anchor group‐functionalised and hydrogen bond‐supported axial ligands

Winter

Mang

Linseis

2022

Zeitschrift anorg allge chemie

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“…Quantum chemical methods have provided insights into the origin of activity and selectivity in the dirhodium-catalyzed reactions. − However, the large size, conformational flexibility, and complexity of the dirhodium catalyst make it challenging to carry out meaningful theoretical treatments using realistic structural models, even with modern-day computing resources. For such reasons, most of the computational studies in this area have been performed using simplified ligand models, such as dirhodium tetraforate Rh 2 (O 2 CH) 4 .…”

Section: Introductionmentioning

confidence: 99%

Computational Mechanism Study of Catalyst-Dependent Competitive 1,2-C→C, −O→C, and −N→C Migrations from β-Methylene-β-silyloxy-β-amido-α-diazoacetate: Insight into the Origins of Chemoselectivity

Yang

2015

ACS Catal.

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Doyle et al. [J. Am. Chem. Soc.201313512441247] recently reported an efficient catalyst-controlled chemoselectivity of competitive 1,2-C→C, −O→C, and −N→C migrations from β-methylene-β-silyloxy-β-amido-α-diazoacetates using dirhodium or copper catalysts. With the aid of density functional theory calculations, the present study systematically probed the mechanism of the aforementioned reactions and the origins of the catalyst-controlled chemoselectivity. Similar to the method reported in the literature, simplified catalyst models Rh2(O2CH)4 and Rh2(N-methylformamide)4 have been used in our initial calculations. However, using the Rh2(O2CH)4 model could not describe the energies of all possible pathways, and high selectivity of three competitive migrations could not be achieved. In order to appropriately describe this 1,2-migration system, real catalyst models Rh2(cap)4, Rh2(esp)2, and CuPF6 have been employed. It was found that the steric and electronic effects of ligands significantly influence the free energy barrier, which ultimately changes the chemoselectivity. In the CuPF6 system, the electronic effects, coupled with the steric factor, give a qualitative explanation for the exclusive chemoselectivity of 1,2-N→C migration over 1,2-C→C or −O→C migration. On the other hand, the bulky ligands of dirhodium catalysts result in the significant steric hindrance around the dirhodium centers and withdrawal of the empty space around the bulky −OTBS group. By analyzing the divergence of three different migration transition states using the distortion/interaction and natural bond orbital analyses, it was found that the 1,2-N→C migration will suffer from a high free energy barrier because of the steric repulsion between the carbonyl group and the carbonyl oxygen of the pyrazolidinone ring. For 1,2-C→C and −O→C migrations, changing the ligands of dirhodium catalysts can change the electronic properties of carbenes, and that is the reason for controlling the major product by changing the dirhodium catalysts. The mechanistic proposal is supported by the calculated chemoselectivities, which are in good agreement with the experimental results.

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“…To shed light on the origin of this unexpected experimental evidence, we investigated the reactivity and selectivity of the observed dirhodium tetraacetate/protein adduct (at His105) with a second Im by quantum chemistry, − within the framework of density functional theory (DFT; see the computational details in the Supporting Information).…”

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confidence: 99%

Unexpected Imidazole Coordination to the Dirhodium Center in a Protein Environment: Insights from X-ray Crystallography and Quantum Chemistry

et al. 2022

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Theoretical study of absorption spectrum of dirhodium tetracarboxylate complex [Rh₂(CH₃COO)₄(H₂O)₂] in aqueous solution revisited

Cited by 7 publications

References 17 publications

Synthesis and crystal structures of rhodium acetate paddle‐wheel complexes with anchor group‐functionalised and hydrogen bond‐supported axial ligands

Synthesis and crystal structures of rhodium acetate paddle‐wheel complexes with anchor group‐functionalised and hydrogen bond‐supported axial ligands

Computational Mechanism Study of Catalyst-Dependent Competitive 1,2-C→C, −O→C, and −N→C Migrations from β-Methylene-β-silyloxy-β-amido-α-diazoacetate: Insight into the Origins of Chemoselectivity

Unexpected Imidazole Coordination to the Dirhodium Center in a Protein Environment: Insights from X-ray Crystallography and Quantum Chemistry

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