Premium
Isomerism of Amides Coordinated to Platinum – X‐ray Crystal Structure of O ‐Bonded Acetamide in a Platinum(II) Complex
Author(s) -
Cini Renzo,
Intini Francesco P.,
Maresca Luciana,
Pacifico Concetta,
Natile Giovanni
Publication year - 1998
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/(sici)1099-0682(199809)1998:9<1305::aid-ejic1305>3.0.co;2-9
Subject(s) - chemistry , platinum , protonation , amide , deprotonation , acetamide , isomerization , pyridine , steric effects , moiety , crystallography , stereochemistry , medicinal chemistry , organic chemistry , catalysis , ion
O‐ bonded amide complexes of platinum(II), which are stable in acetone solution and which undergo solvolysis in neat water with a rate constant as slow as 8.7·10 −5 s −1 , are reported. The structure of a sample compound [Pt(Me 5 dien){ O‐ MeC(O)NH 2 }](CF 3 SO 3 ) 2 has been solved by X‐ray diffraction allowing comparison with related N‐ bonded (amide)platinum complexes. Isomerization from O‐ amide to N‐ amidate species takes place instantaneously under basic conditions. Protonation of the amidate species leads to the N‐ bonded amide. N‐ bonded amides, like the N‐ bonded amidates, represent the thermodynamically preferred species due to the higher affinity of platinum for nitrogen donors. In contrast O‐ bonded amides owe their stability to their kinetic inertness, where a high pH is required for deprotonation of the NH 2 moiety, the leading step in the isomerization process. In the case of the 2‐pyridone complex, the O‐ bonded form is unstable and isomerizes spontaneously to the N‐ bonded form, due to the higher acidity of the protonated pyridine‐like nitrogen atom. Two rotamers are present in both the N‐ pyridone and N‐ pyridonate species. Hindered rotation stems from the steric rigidity of both rotating moieties [(Me 5 dien)Pt and pyridone/pyridonate].