Coupling of Arylamines with Coordinated Arylazopyrimidines in Palladium(II) Complexes

2-(Arylazo)pyrimidine (1) reacts with palladium chloride and gives Pd(aapm)Cl<INF>2</INF> (2) which undergoes a palladium(II)-mediated novel carbon−nitrogen bond formation reaction of the aromatic amines to the ortho-C−H function of the pendant aryl ring in the coordinated 2-(arylazo)pyrimidine. The reactant, Pd(papm)Cl<INF>2</INF> (2a) and the product, Pd(papm-N-C<INF>6</INF>H<INF>4</INF>-OCH<INF>3</INF>-p)Cl (5a) have been characterised by X-ray crystal structure. The coupled products exhibit low energy transitions (NIR region) unlike the parent complex, Pd(aapm)Cl<INF>2</INF>. The cyclic voltammogram shows an oxidation couple at positive potential to SCE. The EHMO calculation suggests that the spectral feature in Pd(aapm)Cl<INF>2</INF> (2) is due to the MLCT [d(Pd)&rlarr2;π*(azo)] whereas in Pd(aapm-N-C<INF>6</INF>H<INF>4</INF>-X-p)Cl (3−6) the transition at the NIR region is due to the intravalence charge transfer (IVCT) transition. <ADDLMAT>Supporting information for this article is available on the WWW under <URL HREF="http://www.wiley-vch.de/contents/jc_2005/2002/i01280_s.pdf">http://www.wiley-vch.de/contents/jc_2005/2002/i01280_s.pdf</URL> or from the author.</ADDLMAT>