B-H Bond Activation in a Rh(III) Hydrido Borohydride Complex Rh(H)(K2-BH4)tBu4(PNCNP) Gives a Rh(I) �-Dihydrogen Complex Rh(η2-H2)tBu4(PNCNP): An Experimental and Theoretical Study

Selvarasu, S and Joshi, G and Senthurpandi, D and Nethaji, M and Jemmis, ED and Jagirdar, BR (2024) B-H Bond Activation in a Rh(III) Hydrido Borohydride Complex Rh(H)(K2-BH4)tBu4(PNCNP) Gives a Rh(I) �-Dihydrogen Complex Rh(η2-H2)tBu4(PNCNP): An Experimental and Theoretical Study. In: Organometallics .

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Abstract

Rh(III) pincer hydrido chloride and borohydride complexes Rh(H)CltBu4(PNCNP) (1) tBu4(PNCNP) = 2,6-bis((di-tert-butylphosphaneyl)amino)benzen-1-ide and Rh(H)(K2-BH4)tBu4(PNCNP) (2) have been synthesized and characterized. Heating the Rh(H)(K2-BH4)tBu4(PNCNP) complex (2) at 336 K in tetrahydrofuran (THF) afforded the Rh(I) �-H2 complex, Rh(η2-H2)tBu4(PNCNP) (3), and H3B·THF via the B-H bond activation of the borohydride. The Rh(η2-HD)tBu4(PNCNP) (3-HD) isotopomer was also prepared by heating the Rh(H)(K2-BD4)tBu4(PNCNP) complex (2-BD4) at 336 K in THF. The formation of Rh(η2-H2)tBu4(PNCNP) (3) was established using 1JH,D coupling constant and variable temperature spin-lattice relaxation time measurements and supported by density functional theory (DFT) calculations. At 273 K, the Rh(η2-H2)tBu4(PNCNP) complex (3) reverted back to the Rh(H)(K2-BH4)tBu4(PNCNP) complex (2) upon reaction with H3B·THF. The Rh(η2-H2)tBu4(PNCNP) complex (3) was also obtained independently by two alternative routes. The reaction of Rh(η2-H2)tBu4(PNCNP) (3) with N2 at 273 K afforded the Rh(N2)tBu4(PNCNP) complex (4); this reaction was found to be reversible. The reaction of Rh(η2-H2)tBu4(PNCNP) (3) with CH3CN, CO, and O2 occurred instantaneously and yielded the corresponding products Rh(CH3CN)tBu4(PNCNP) (5), Rh(CO)tBu4(PNCNP) (6), and Rh(η2-O2)tBu4(PNCNP) (7), respectively. These observations together with computational studies showed that the binding strengths of CH3CN, CO, and O2 with the Rh center are significantly greater than those of H2 and N2. © 2024 American Chemical Society.

Item Type:	Journal Article
Publication:	Organometallics
Publisher:	American Chemical Society
Additional Information:	The copyright for this article belongs to the publisher.
Keywords:	Activation analysis; Chemical activation; Complexation; Relaxation time; Rhodium compounds; Spectroscopic analysis; Synthesis (chemical); Thorium compounds, Bond activation; Borohydride complexes; Borohydrides; Chloride complexes; Dihydrogen complexes; H-bonds; Synthesised; Tetra-hydrofuran; Tetrahydrofurans; Theoretical study, Spin-lattice relaxation
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	24 Oct 2024 11:39
Last Modified:	24 Oct 2024 11:39
URI:	http://eprints.iisc.ac.in/id/eprint/86609

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