The Schiff base, 2-[(2,3-dihydro-1H-inden-4-ylimino)methyl]-5-nitrophenol coordinates to Mn(II), Cu(II), Zn(II), and Pd(II) ions through the phenolic O and imine N atoms. The complexes are characterized by physicochemical and spectroscopic methods. The metal complexes formed as [ML2]xH2O with exception of the Cu(II) complex which is anhydrous. Spectroscopic data corroborate the adoption of a four-coordinate, tetrahedral geometry for the Mn(II), and Zn(II) complexes, and a four-coordinate, square planar geometry for the Cu(II) and Pd(II) complexes. None is an electrolyte in DMSO. The in vitro anticancer activities of the metal free ligand, Cu(II), Zn(II), and Pd(II) complexes against MCF-7 (human breast adenocarcinoma) and HT-29 (colon carcinoma) cells reveal that the Pd(II) complex has the best cytotoxic activity against MCF-7 cells with an IC50 of 5.94？μM, which is within the same order of activity as cisplatin. Furthermore, the ligand and the Zn(II) complex exhibit broad-spectrum activity against two gram-positive bacteria, three gram-negative bacteria, and a fungus with inhibitory zones range of 10.0–20.0 and 10.0–17.0？mm, respectively. 1. Introduction Tridentate aminoindane Schiff base Cr(III) compounds have been used as catalysts in enantioselective inverse-electron-demand hetero-Diels-Alder reactions of α,β-unsaturated aldehydes and ring opening of meso-aziridines [1, 2]. Furthermore, some amino-1-indanols possess valuable bronchodilator properties, For example, 6-methoxy-2-isopropylamino-1-indanol [3], while N-propargylamine-1(R)-aminoindane exhibits antiapoptotic properties against dopaminergic SH-SY5Y cells. Additionally, Schiff bases derived from indane-1, 3-dione-2-imine-N-acetic acid, 2-imino-N-2-propionic acid and ninhydrin, glycine/L-alanine, and their metal(II) complexes exhibit unique geometries, and good antimicrobial activities against E. coli, P. mirabilis, S. aureus, and P. faecalis [4, 5], while those derived from 4-amino-1,3-dimethyl-2,6-pyridinedione and various hydroxy benzaldehyde are potent antimicrobials. Tricyclic pyrimidine and aminobenzene sulfonamido Schiff bases showed anti-HIV activity and high antitumor activity with low therapeutic index against murine S-180 carcinoma [6–8], and N-substituted-3-chloro-2-azetidinones Schiff bases have good anthelmintic activity against earthworms [9]. Extensive literature search shows that no work is reported on the Schiff base, 2-[(2,3-dihydro-1H-inden-4-ylimino)methyl]-5-nitrophenol (derived from condensation of 4-aminoindane and 2-hydroxy-5-nitrobenzaldehyde) and its Mn(II), Cu(II),
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