Versatile Reactivity of Half-Sandwich Rhodium(III) Iminophosphonamide Complexes

Roman I Nekrasov; Tat'yana A Peganova; Ivan V Fedyanin; Evgenii I Gutsul; Oleg A Filippov; Natalia V Belkova; Alexander M Kalsin

doi:10.1021/acs.inorgchem.2c02478

Versatile Reactivity of Half-Sandwich Rhodium(III) Iminophosphonamide Complexes

Inorg Chem. 2022 Oct 10;61(40):16081-16092. doi: 10.1021/acs.inorgchem.2c02478. Epub 2022 Sep 23.

Authors

Roman I Nekrasov¹, Tat'yana A Peganova¹, Ivan V Fedyanin¹, Evgenii I Gutsul¹, Oleg A Filippov¹, Natalia V Belkova¹, Alexander M Kalsin¹

Affiliation

¹ A.N. Nesmeyanov Institute of Organoelement Compounds of Russian Academy of Sciences, 28 Vavilov Street, 119334 Moscow, Russian Federation.

PMID: 36149890
DOI: 10.1021/acs.inorgchem.2c02478

Abstract

Novel 18e̅ and 16e̅ pentamethylcyclopentadienyl rhodium(III) complexes [(η⁵-C₅Me₅)RhX(NPN)] (1a,b, X = Cl; 2a-c, X = PF₆, BAr₄^F) with chelating zwitterionic iminophosphonamide (NPN) ligands (Ph₂P(NR)(NR'); a, R = R' = p-Tol; b, R = p-Tol, R' = Me; c, R = R' = Me) were synthesized and characterized by single-crystal X-ray diffraction. In the 16e̅ complexes 2, the rhodium (Rh) atom is efficiently stabilized by π-donation of unshared N electrons, thus hampering coordination of the external ligands and rendering the 18e̅ complexes labile. Due to low coordination enthalpy, the cationic 18e̅ monocarbonyl and pyridine adducts 2a·L are stable only at low temperatures. At room temperature, 2·CO adducts readily give stable carbonyl-carbamoyl complexes [(η⁵-C₅Me₅)Rh(CO){(CO(NR')Ph₂P(NR)}]⁺ (4) formed as a result of CO insertion into the Rh-N bond, thus showing high nucleophilicity of the N atoms in 18e̅ complexes. High basicity of the Na⁺NPN^- precursors caused side deprotonation of the η⁵-C₅Me₅ ligand during the synthesis of 1 that yields unstable fulvene Rh(I) complexes [(η⁴-C₅Me₄CH₂)Rh{Ph₂P(NR)(NR')₂}] (3a,b). Complex 3a undergoes a facile reaction with isoprene to yield an unusual [(η⁵:η¹-C₅Me₄(CH₂)C(Me)═CHCH₂)Rh(NPN)] complex─the first example of intermolecular 1,4-metallacycloaddition of diene to the Rh-fulvene complex.