Palladacycles having normal and spiro chelate rings designed from bi- and tridentate ligands with an indole core: structure, synthesis and applications as catalystsElectronic supplementary information (ESI) available: Crystal data and refinement parameters (Tables S1 and S3), bond lengths and angles (Tables S4 and S5), and distances of non-covalent interactions (Tables S6 and S7). Fig. S1 and S2: molecular structure of A/B. Figures of secondary interaction of A, B, L1 and L3 (Fig. S3-S6). Figure

1-Pyridin-2-ylmethyl-1 H -indole-3-carbaldehyde and 1-((1-benzyl-1 H -1,2,3-triazol-4-yl)methyl)-1 H -indole-3-carbaldehyde were synthesized. Their condensation with benzyl amine resulted in indole core containing Schiff bases benzyl-(1-pyridin-2-ylmethyl-1 H -indol-3-ylmethylene)amine ( L1 ) and benzyl-[1-(1-benzyl-1 H -[1,2,3]triazole-4-ylmethyl)-1 H -indol-3-yl methylene]amine ( L2 ) respectively, unknown hitherto. The K 2 CO 3 -promoted sulfenylation of the indole formed 3-(pyridin-2-ylsulfanyl)-1 H -indole ( L3 ), also unknown so far. The yield of L1-L3 was 72-93%. L1 and L2 on reaction with sodium tetrachloropalladate( ii ) in the presence of CH 3 COONa give complexes [Pd( L1 / L2 -H)Cl] ( 1 / 2 ) in which they bind in a tridentate (N, C − , N′) pincer mode. L3 on reaction with [(MeCN) 2 PdCl 2 ] results in a dimeric palladacycle [Pd( L3 -H)Cl] 2 ( 3 ) with a spiro ring. The precursor aldehydes, L1-L3 and the Pd( ii )-complexes derived from them, were characterized using 1 H and 13 C{ 1 H} NMR and HR-MS. Complexes 2 and 3 , ligands L1 and L3 and the precursor aldehydes of L1 and L2 were authenticated with single crystal X-ray diffraction. The Pd-C bond distances (Å) are 1.932(8)/2.115(3) ( 2 / 3 ). The Pd-N bond lengths (Å) are: 2.063(7) and 2.028(7) for 2 and 2.053(3) and 2.019(3) for 3 . These complexes have been found to be efficient as catalysts for the Suzuki-Miyaura coupling of ArCl ( 3 as a catalyst) and ArBr and allylation of a variety of aldehydes ( 1 and 2 as catalysts). The optimum loading of the complexes as catalysts is 0.001-0.01 and 1 mol% respectively for the two reactions, which appear to follow a homogeneous pathway. Palladacycles with normal and spiro rings catalyze Suzuki-Miyaura coupling of ArBr/ArCl/allylation of aldehydes at 0.001/1 mol% loading.