Square‐Planar Pt^II versus Octahedral Pt^IV Halido Complexes: ¹⁹⁵Pt NMR Explained by a Simple Empirical Approach

Abstract

In this work, we show by a simple empirical approach that a linear relationship between observed 195Pt NMR frequencies and the overall sum of the ionic radii of the coordinated halido ligands [Σ(rh)] exists in square‐planar PtII complexes of the type [PtXnY4–n]2– (1 ≤ n ≤ 4; X, Y = Cl, Br, I). Another finding was that such square‐planar complexes could be empirically described as octahedral complexes, with the two lobes of the 5dz² orbital above and below the coordination plane acting as two pseudo‐halido ligands, each showing a constant apparent radius of around 207 pm. According to our approach, the overall apparent radius of around 415 pm produces constant 195Pt NMR shielding for all [PtXnY4–n]2– complexes of about 10450 ppm. This result is 1) consistent with the theoretically calculated overall 5d shell lone‐pair shielding observed in square‐planar PtII with respect to octahedral PtIV complexes and 2) almost coincident with the already measured chemical shift anisotropy (CSA) of the K2[PtCl4] complex both in solution and in the solid state (single crystal).

Platinum-Nucleos(t)ide Compounds as Possible Antimetabolites for Antitumor/Antiviral Therapy: Properties and Perspectives

“…They can act as prodrugs and, once introduced inside cells by the plasma membrane nucleoside transporters, require intracellular phosphorylation to generate their pharmacologically active triphosphate form [ 38 ]. Many investigations have focused on the study of the synthesis, structural features, and antitumor and/or antiviral biological effects of platinated nucleotides [ 74 , 79 , 89 , 126 , 127 , 128 , 129 , 130 , 131 , 132 , 133 ]. Recently, our research efforts were devoted to a deeper comprehension of the cellular metabolic mechanisms involving some model platinated nucleos(t)ides, to confirm their potential as antimetabolites.…”

Predicting 195Pt NMR Chemical Shifts in Water‐Soluble Inorganic/Organometallic Complexes with a Fast and Simple Protocol Combining Semiempirical Modeling and Machine Learning

“…It is used for effectively establishing chemical structures and elucidating catalytic mechanisms. Pt complexes are notable in this regard, as magnetic 195 Pt nuclei exhibit NMR signals in an extremely wide range from −6000 to 7000 ppm, or wider [2–4] . At the same time, Pt complexes are well‐established (pre)catalysts widely used in the laboratory and industry.…”

“…Pt complexes are notable in this regard, as magnetic 195 Pt nuclei exhibit NMR signals in an extremely wide range from À 6000 to 7000 ppm, or wider. [2][3][4] At the same time, Pt complexes are well-established (pre)catalysts widely used in the laboratory and industry. Platinum catalysts for reactions such as C-Si [5][6][7][8] and C-B [7,[9][10][11][12][13] bond formation and allylic alcohol amination [14][15][16][17] were thoroughly developed.…”

“…Contrary to the cases of 1 H and 13 C, only machine learning established for individual classes of Pt complexes exists. Among them are linear models for Pt halides [4,80] and a pioneering neural network-based model for Pt complexes with amine, pyridine, and carboxylate ligands from 2006. [81] A widely used approach in the past decade is to use quantum chemical (QC) modeling to predict NMR data for Pt complexes (see Refs.…”

Measuring Self‐Association of Pt Complexes by 195Pt NMR

“…The intramolecular effect of attachment of halogen ligand to Pt atoms on 195 Pt chemical shift is a relatively well investigated [7] whereas the intermolecular effect of Pthalogen moiety on 195 Pt chemical shift in partner molecule in dimer at this stage cannot be interpreted. We consider that the deshielding may be the consequence of a small charge delocalization from the Pt atom due to the action of the large dipole of the Pt-halogen moiety of the partner molecule in aggregate located directly above (see Figure 2).…”