Aqueous chemistry of platinum and palladium complexes. Part 2. Synthesis and crystal structure of a palladium hydroxo complex [Pd(terpy)(OH)]ClO4·H2O (terpy = 2,2′:6′,2″-terpyridine)

Abstract

The complex [Pd(terpy)(ONO₂)]NO₃(terpy = 2,2′:6′,2″-terpyridine) can be prepared from the reaction of Pd(NO₃)₂ with terpy in dilute nitric acid or from metathesis of [Pd(terpy)Cl]Cl using AgNO₃. It dissolves in water with hydrolysis of the co-ordinated nitrato group to form [Pd(terpy)(OH₂)]²⁺. Attempts to isolate this complex were unsuccessful. Addition of sodium perchlorate to a solution of [Pd(terpy)(ONO₂)]NO₃ at pH 10.5 afforded orange needles of [Pd(terpy)(OH)]ClO₄·H₂O. The Pd–OH bond distance is 1.966(3)Å, and the hydroxo group forms strong hydrogen bonds with the molecule of water of crystallisation.