An Unsymmetric Imino-Phosphanamidinate Ligand and its Y(III) Complex: Synthesis, Characterization, and Catalytic Hydroboration of Carbonyl Compounds

Srinivas Anga; Joydev Acharya; Vadapalli Chandrasekhar

doi:10.1021/acs.joc.0c02383

An Unsymmetric Imino-Phosphanamidinate Ligand and its Y(III) Complex: Synthesis, Characterization, and Catalytic Hydroboration of Carbonyl Compounds

J Org Chem. 2021 Feb 5;86(3):2224-2234. doi: 10.1021/acs.joc.0c02383. Epub 2020 Dec 2.

Authors

Srinivas Anga¹, Joydev Acharya^{1

2}, Vadapalli Chandrasekhar^{1

2}

Affiliations

¹ Tata Institute of Fundamental Research Hyderabad, Gopanpally 500046, Hyderabad, India.
² Department of Chemistry, IIT Kanpur, Kanpur 208016, India.

PMID: 33290079
DOI: 10.1021/acs.joc.0c02383

Abstract

An imino-phosphanamide ligand, [NHI^iPr2Me2P(Ph)NH-2,6-ⁱPr₂C₆H₃] (LH), containing two different N-substituents was prepared by the direct reaction of the lithium salt of N-heterocyclic imine (NHI) with phenylchloro-2,6-diisopropylphenyl phosphanamine, PhP(Cl)NH-2,6-ⁱPr₂-C₆H₃. Reaction of LH with Y(N(SiMe₃)₂)₃ afforded the heteroleptic complex, [{L}Y(N(SiMe₃)₂)₂] (1), by elimination of HN(SiMe₃)₂. Compound 1 was characterized by multinuclear NMR and X-ray crystallography. In the complex, the Y(III) center was found to be tetracoordinate in a distorted tetrahedral geometry. The ligand, imino-phosphanamidinate, [L]^-, functions in a chelating manner, and its coordination to Y(III) results in a distorted 4-membered YPN₂ ring. As a proof of principle of its activity, 1 was used as a precatalyst for the hydroboration of various aldehydes and ketones using HBpin as the hydrogen source. The hydroboration reaction was rapid and clean even with low catalyst loadings (0.01-0.1 mol %). In addition, a very good functional group tolerance was observed in these reactions.