13C and 207Pb NMR Chemical Shifts of Dirhodio- and Dilithioplumbole Complexes: A Quantum Chemical Assessment

Radhika Narayanan; Marisa Nakada; Minori Abe; Masaichi Saito; Masahiko Hada

doi:10.1021/acs.inorgchem.9b02367

¹³C and ²⁰⁷Pb NMR Chemical Shifts of Dirhodio- and Dilithioplumbole Complexes: A Quantum Chemical Assessment

Inorg Chem. 2019 Nov 4;58(21):14708-14719. doi: 10.1021/acs.inorgchem.9b02367. Epub 2019 Oct 21.

Authors

Radhika Narayanan¹, Marisa Nakada², Minori Abe¹, Masaichi Saito², Masahiko Hada¹

Affiliations

¹ Department of Chemistry, Graduate School of Science and Engineering , Tokyo Metropolitan University , 1-1 Minami-Osawa , Hachioji , Tokyo 192-0397 , Japan.
² Department of Chemistry, Graduate School of Science and Engineering , Saitama University , 255 Shimo-okubo , Sakura-ku, Saitama , Saitama City 338-8570 , Japan.

PMID: 31633917
DOI: 10.1021/acs.inorgchem.9b02367

Abstract

Density functional theory (DFT) and zeroth-order regular approximation DFT calculations were performed to investigate the electronic structures and ¹³C and ²⁰⁷Pb nuclear magnetic resonance (NMR) chemical shifts of metal-coordinated plumboles, namely, monorhodioplumbole ([Rh-plumbole]^-), dirhodioplumbole (Rh₂-plumbole), and dilithioplumbole (Li₂-plumbole), which have a five-membered ring containing lead. The molecular orbital correlation diagram and extended transition state-natural orbitals for chemical valence analysis of the [Rh-plumbole]^- and Rh₂-plumbole complexes showed that the plumbole is primarily a π-donor, with π-donation being dominant in the Rh₂-plumbole complex. The present calculations show that the Pb-C_α internuclear distances are longer in the Rh₂-plumbole complex than in [Rh-plumbole]^- because of the combined effect of strong π-donation and weak π-back-donation in the Rh₂-plumbole complex. The calculated ²⁰⁷Pb and ¹³C_α NMR chemical shifts agree with the experimental trends reasonably well. The influences of the relativistic effect, role of the functional, effect of the solvent, and dependence of the exact exchange admixture on the calculated ²⁰⁷Pb and ¹³C_α NMR chemical shifts were investigated. The NMR chemical shift trend of the ²⁰⁷Pb atom in the complexes originates from the paramagnetic and spin-orbit contributions. NMR component analysis revealed that the upfield shift of the ¹³C_α atoms of the [Rh-plumbole]^- and Rh₂-plumbole complexes compared to that of the Li₂-plumbole complex is mainly due to the decrease in the paramagnetic term.