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

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 )).