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

Abstract

Dedicated to Professor Rinaldo Poli on the occasion of his 65th birthday. The square planar bisnitrile platinum(II) derivatives PtCl 2 (NCR) 2 (R = Ph (1 a); Et (1 b); p-C 6 H 4 F (1 c); p-C 6 H 4 t Bu (1 d); m-C 6 H 3 Me 2 (1 e); o,p-C 6 H 2 Me 3 (1 f)) react with tetrabutylammonium hydroxide to render the monoaquo [NBu 4 ][trans-PtCl(HNCOR) 2 (OH 2 )] (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 [NBu 4 ][trans-PtCl(HNCOPh) 2 (NH 2 R')] (R' = H (3), NH 2 (4), t Bu (5 a), p-C 6 H 4 Me (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 [NBu 4 ][PtClX 2 (HNCOPh) 2 (OH 2 )] (X = Cl (6 a), Br (6 b), I (6 c)).