Two novel 3d (Ni)/4 f (Dy and Y) metal ions and polydentate organic ligands (H2L1 and H2L2) based tetranuclear coordination complexes, [(L1)4NiII2DyIII2(DMF)2(NO3)2]⋅DMF (1) and [(L2)4NiII2YIII2(DMF)2(NO3)2]⋅DMF⋅H2O (2), have been synthesized and characterized using IR, elemental analysis and single crystal X-ray diffraction studies. The application of these complexes as C−C bond coupling homogeneous catalysts has been logically shown. The complex 1 acts as an excellent catalyst (with a very low catalyst loading of 0.17 mol%) for the syntheses of a wide range of bis(indolyl)methane derivatives in good yields using various indoles and aromatic/hetero aromatic aldehydes under optimized reaction conditions. A plausible reaction mechanism has been proposed showing the coordinative binding of the aromatic aldehyde at NiII centre along with the associative π-stacking interaction between the ligand (H2L1) and the phenyl ring of the aromatic aldehyde and/or indole leading to the formation of the desired bis(indolyl)methanes under the metal assisted C−C bond forming reaction with subsequent elimination of water molecule in polar protic solvent. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim