Palladium(ii) Dppe Arylazoimidazole Complexes: Synthesis, and Spectroscopic Characterization

Understanding photo induced electron transfer is a major scientific objective and is of technological impor tance for the design of synthetic molecular devices [1–3]. It is clear that the ability to mimic the natural photosyn thesis process in the laboratory would have great techno logical significance in terms of solar energy conversion and storage. Synthetic porphyrin based assemblies have been extensively used as models for molecular organiza tion and energy/electron transfer processes [4–8]. Many clever and ingenious reaction center models have been prepared, and it is clear that the sophistication of synthet ic multicomponent species that mimic the primary events of natural photosynthesis has increased tremen dously. However, as the types and numbers of compo nents are increased, the level of complexity also expands, and model systems become more difficult to prepare. To a large extent, progress in this area is still significantly synthesis limited. Most of the existing model systems are linked through organic spacers [5–7]. The synthetic methods for these systems typically are multistep pro cesses, and yields are often extremely low. Recently some attempts have been turned to developing new strategies for designing assemblies that can achieve sequential mul tistep electron transfer processes. Sessler et al. have pre pared model systems that linked donors and acceptors through hydrogen bonds [9, 10]. Sauvage et al. have de signed bis(terpyridyl)porphyrins and utilized the terpy ridyl group to build donor/acceptor array. In this paper, the reaction of RaaiR' with lower case Palladium(II) dppe derivatives was examined and the products, [Pd(dppe)(RaaiR')](OTf)3 [RaaiR' = p R–C6H4– N=N–C3H2–NN–1–R', (1–3), abbreviated as a N,N' chelator, where N(imidazole) and N(azo) are represent ed by N and N', respectively; R = H (a), Me (b), Cl (c) and R' = Me (1), CH2CH3 (2), CH2Ph (3), OSO2CF3 is the triflate anion] were isolated. The complexes were well charecterised by IR, 1H NMR (1D & 2D) and mass spectrometry.