Synthesis of Cr-coordination complexes, (η6-SWNT)Crx(CO)y: The synthesis was carried out in argon atmosphere using standard Schlenk techniques. The SWNT material (40 mg, 3.33 mmol of carbon) was dispersed in dibutyl ether (15 nm) by ultrasonication (Aquasonic 50HT, VWR Scientific sonic power 75 W, frequency ~40 kHz) for 2 h, and chromium hexacarbonyl (122 mg, 0.56 mmol, F.W.=220.06) was added to the homogeneous suspension. The mixture was degassed with argon for 1 h and then heated to 110 °C. The reactions were conducted over periods of 1 day (24 h), 3 days and 5 days. After reaction, the mixture was cooled to room temperature and filtered using a 0.22 μm PTFE membrane and the solid washed with dibutyl ether and hexane to remove unreacted reagents. The product was dried under vacuum in a desiccator overnight in dark to obtain (η6-SWNT)Crx(CO)y as a black solid.