Predicting Pt-195 NMR Chemical Shift and 1J(195Pt-31P) Coupling Constant for Pt(0) Complexes Using the NMR-DKH Basis Sets

Joyce H C E Silva,Diego F S Paschoal,Hélio F Dos Santos

doi:10.3390/magnetochemistry7110148

Abstract

Pt(0) complexes have been widely used as catalysts for important reactions, such as the hydrosilylation of olefins. In this context, nuclear magnetic resonance (NMR) spectroscopy plays an important role in characterising of new structures and elucidating reaction mechanisms. In particular, the Pt-195 NMR is fundamental, as it is very sensitive to the ligand type and the oxidation state of the metal. In the present study, quantum mechanics computational schemes are proposed for the theoretical prediction of the Pt-195 NMR chemical shift and 1J(195Pt–31P) in Pt(0) complexes. The protocols were constructed using the B3LYP/LANL2DZ/def2-SVP/IEF-PCM(UFF) level for geometry optimization and the GIAO-PBE/NMR-DKH/IEF-PCM(UFF) level for NMR calculation. The NMR fundamental quantities were then scaled by empirical procedures using linear correlations. For a set of 30 Pt(0) complexes, the results showed a mean absolute deviation (MAD) and mean relative deviation (MRD) of only 107 ppm and 2.3%, respectively, for the Pt-195 NMR chemical shift. When the coupling constant is taken into account, the MAD and MRD for a set of 33 coupling constants in 26 Pt(0) complexes were of 127 Hz and 3.3%, respectively. In addition, the models were validated for a group of 17 Pt(0) complexes not included in the original group that had MAD/MRD of 92 ppm/1.7% for the Pt-195 NMR chemical shift and 146 Hz/3.6% for the 1J(195Pt–31P).

Highlights

There is a great interest in the study of Pt compounds due to their application as anticancer drugs [1,2] and due to their use as heterogeneous or homogeneous catalysts [3]in modern organic chemistry [4,5]
For a set of 30 Pt(0) complexes, the results showed a mean absolute deviation (MAD) and mean relative deviation (MRD) of only 107 ppm and 2.3%, respectively, for the Pt-195 nuclear magnetic resonance (NMR) chemical shift
When the coupling constant is taken into account, the MAD and MRD for a set of 33 coupling constants in 26 Pt(0) complexes were of 127 Hz and 3.3%, respectively

Summary

Introduction

There is a great interest in the study of Pt compounds due to their application as anticancer drugs [1,2] and due to their use as heterogeneous or homogeneous catalysts [3]in modern organic chemistry [4,5]. There is a great interest in the study of Pt compounds due to their application as anticancer drugs [1,2] and due to their use as heterogeneous or homogeneous catalysts [3]. Pt(0) complexes and their structural diversity, the nuclear magnetic resonance (NMR) spectroscopy for the Pt-195 nucleus is an important tool used for mechanistic studies [13]. NMR can help in structural characterization of the complexes, cis/trans discrimination, stoichiometry, elucidation of reaction mechanisms, etc. The studies on NMR of Pt-195 date back to the 1960s, when the effect of structure on the Pt chemical shift was first described [14].

Methods

Results

Conclusion