A Study of the Formation, Purification, Ligand Substitution Chemistry, and Application as a SWNT Growth Catalyst of the Nanocluster (Preprint)

The synthetic conditions for the isolation of the iron-molybdenum nanoc1uster FeMoC, along with its application as a catalyst precursor for VLS growth of SWNTs have been studied. As prepared FeMoC is contaminated with the Keplerate cage without the Keggin template however, extraction of pure FeMoC may be accomplished by Soxhlet extraction with EtOH. The resulting EtOH solvate is consistent with the replacement of the water ligands coordinated to Fe being substituted by EtOH. FeMoC-EtOH has been characterized by IR, UV-vis spectroscopy, MS, XPS and 31P NMR. The solid state 31P NMR spectrum for FeMoC-EtOH suggests little effect of the paramagnetic Fe3 centers in the Keplerate cage on the Keggin ions phosphorous. The high chemical shift anisotropy, and calculated T1 and T2 values are consistent with a weak magnetic interaction between the Keggin ions phosphorus symmetrically located within the Keplerate cage. Increasing the FeCl2 concentration and decreasing the pH of the reaction mixture optimizes the yield of FeMoC. The solubility and stability of FeMoC in H2O and MeOHH20 is investigated.