10.1021/om010449g.s002 Jonathan W. Slater Jonathan W. Slater Donocadh P. Lydon Donocadh P. Lydon Nathaniel W. Alcock Nathaniel W. Alcock Jonathan P. Rourke Jonathan P. Rourke Doubly Cyclometalated Pyridazines:  Contrasting Behavior with Palladium and Platinum American Chemical Society 2001 metal source cycloplatination cyclometalation chloride palladium 2001-09-11 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Doubly_Cyclometalated_Pyridazines_Contrasting_Behavior_with_Palladium_and_Platinum/3766491 The cyclometalation of 3,6-diphenylpyridazines with palladium and platinum has been studied. When palladium acetate is used as the metal source, two sequential cyclometalations are observed, with the first cyclometalation deactivating the system toward a second cyclometalation. Both monocyclopalladated and dicyclopalladated species have been isolated and characterized as their acetylacetonate derivatives. When potassium tetrachloroplatinate is used as the metal source, only double cycloplatination is observed:  the first cycloplatination activates the system toward a second cycloplatination through a combination of nitrogen coordination and a chloride bridging two platinums. A doubly cycloplatinated compound has been isolated as its triphenylphosphine derivative, which has been fully characterized:  the single-crystal X-ray structure shows that the two platinums are bridged by a chloride.