Tetranuclear Rh4 chains supported by meso-Ph2PCH2P(Ph)CH2P(Ph)CH2PPh2 (meso-dpmppm) capturing H2 to afford Rh4H3 hydride complexes

• Published in: Journal of organometallic chemistry Vol. 939; p. 121771
• Main Authors: Tanase, Tomoaki, Morita, Yuka, Sato, Kazuki, Aoki, Risa, Yoshii, Akiko, Nakamae, Kanako, Ura, Yasuyuki, Nakajima, Takayuki
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2021
• Subjects: Hydride; Oxidative addition of hydrogen; Rhodium; Tetranuclear complex; Tetraphosphine; Tetranuclear complex; Hydride; Tetraphosphine; Rhodium; Oxidative addition of hydrogen
• ISSN: 0022-328X; 1872-8561
• DOI: 10.1016/j.jorganchem.2021.121771

•Tetraphosphine meso-dpmppm supports bent tetranuclear Rh4 chains.•The Rh4 core reacted with H2 (1 atm) to afford Rh4H3 hydride complexes.•The linear Rh4H3 structure was determined by XRD and DFT calculations. A linear tetraphosphine, meso-Ph2PCH2P(Ph)CH2P(Ph)CH2PPh2 (meso-dpmppm), was found to support a series of bent tetranuclear rhodium(I) arrays of [Rh4(μ−Cl)Cl2(CO)4(meso-dpmppm)2]Cl (1), [Rh4(μ−Cl)2(meso-dpmppm)2]X2 (X = PF6 (2a), BF4 (2b), TfO (2c), BPh4 (2d)), and [Rh4(μ−Cl)(CH3CN)2(CO)4(meso-dpmppm)2](TfO)3 (3) which are regarded as tetranuclear extended Vaska-type RhI complexes. Two meso-dpmppm ligands with mutual syn-arrangement established a flexible bending chains of {Rh4(meso-dpmppm)2}4+ which accommodated a variety of ligand sets of {(μ−Cl)Cl2(CO)4}3‒, {(μ−Cl)2(CO)4}2‒, and {(μ−Cl)(CH3CN)2(CO)4}‒ with Rh–Rh–Rh angles of 142.18(1)–161.54(1)°. The tetranuclear rhodium(I) core of 2 was interestingly reactive toward H2 (1 atm) under mild conditions at room temperature to afford {Rh4H3}3+ hydride complexes with linear RhI∙∙∙RhII–RhII∙∙∙RhI array, [Rh4(μ−Cl)2(μ−H)3(μ−CO)(CO)2(meso-dpmppm)2]X (X = PF6 (4a), BF4 (4b), TfO (4c)), where the positions of three hydride ligands were estimated with 1H, 1H{31P}, and 31P{1H} NMR spectra, a single crystal X-ray diffraction analysis, and DFT calculations. The linearly ordered {Rh4H3}3+ species that store four electrons from dihydrogen molecules is the first example of linear Rh hydride chains and would be useful platform for exploring cooperative reactions promoted by constrained multimetallic centers. [Display omitted]