Trans‐Amidate Platinum Complexes Anchoring Water and N‐donor Molecules. The Importance of Hydrogen Bonding

• Published in: European journal of inorganic chemistry Vol. 2022; no. 22
• Main Authors: Gimeno‐Prat, Antonio, Martín, Antonio, Baya, Miguel, Casas, José M.
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 08.08.2022
• Subjects: Amidate; Bonding strength; Dehydration; Halogens; Hydrogen bonding; Hydrogen bonds; Inorganic chemistry; Ligands; Magnesium sulfate; Molecular sieves; N-donor ligands; Oxidation; Platinum; Water; Water chemistry
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.202200163

The square planar bisnitrile platinum(II) derivatives PtCl2(NCR)2 (R=Ph (1 a); Et (1 b); p‐C6H4F (1 c); p‐C6H4tBu (1 d); m‐C6H3Me2 (1 e); o,p‐C6H2Me3 (1 f)) react with tetrabutylammonium hydroxide to render the monoaquo [NBu4][trans‐PtCl(HNCOR)2(OH2)] (2 a–2 f). The water molecule is σ‐coordinated to platinum and the binding is reinforced by two strong hydrogen bonds to the neighboring amidate ligands (OH⋅⋅⋅OC). Substitution of water in 2 a by N‐donor ligands can be efficiently achieved only in the presence of a dehydrating agent as magnesium sulphate or 4 Å molecular sieves. By following this strategy, compounds [NBu4][trans‐PtCl(HNCOPh)2(NH2R’)] (R’=H (3), NH2 (4), tBu (5 a), p‐C6H4Me (5 b) have been isolated. The incoming ligands are σ‐coordinated to platinum and also establish strong hydrogen bonds to the amidates (NH⋅⋅⋅OC). Treatment of 2 a with halogens causes oxidation at the metal center, rendering the platinum(IV) derivatives [NBu4][PtClX2(HNCOPh)2(OH2)] (X=Cl (6 a), Br (6 b), I (6 c)). A series of novel trans‐amidate platinum(II) and platinum(IV) complexes are described herein. The ligand system allows to coordinate selectively one water, ammonia, hydrazine, or primary amine to the metal center. Strong hydrogen bonds are formed with the amidates, reinforcing the ligand binding to the platinum center and distorting the initially expected trans effect.