Bimetallic nickel complexes with bridging dithiolato Schiff base ligands: synthesis, mass spectral characterisation and electrochemistry

Schiff base dithiols with thiophene or phenyl linkers were prepared from condensation of the dialdehydes 2,5-(OHC)2C4H2S, 1,3-(OHC)2C6H4, 1,4-(OHC)2C6H4 and 1,4′-(OHC)2(C6H4)2 with 4-H2NC6H4(SH). The Schiff base dithiols readily reacted with Ni(η5-C5H5)(PR3)Br (R=Bu or Ph) in the presence of Et3N to form bimetallic complexes (η5-C5H5)(PR3)NiSC6H4NC(H)ArC(H)NC6H4SNi(PR3)(η5-C5H5) (Ar=C4H2S (6), 1,3-C6H4 (7), 1,4-C6H4 (8), 1,4′-(C6H4)2 (9). The bimetallic nature was established from elemental analysis and mass spectrometry. Cyclic voltammetry of complexes 6, 8 and 9 are indicative of electronic communication between the nickel centres via the bridging dithiolato Schiff base ligands.