Preparation of η2-complexes of fullerenes by reduction. Crystal structure and optical properties of {Ni(dppp)·(η2-C70)}·(C6H4Cl2)0.5?

Dalton Transactions Pub Date: 2011-08-09 DOI: 10.1039/C1DT10839E

Abstract

The new reduction method for preparation of η2-complexes of fullerenes with nickel–1,3-bis(diphenylphosphino)propane has been developed in which Ni(dppp)Cl2 and C60(C70) mixtures are reduced with sodium tetraphenylborate. Single crystals of the first η2-complex of nickel with fullerene C70: {Ni(dppp)·(η2-C70)}·(C6H4Cl2)0.5 (1) (C6H4Cl2 = o-dichlorobenzene) have been obtained as well as the previously described complex with fullerene C60: {Ni(dppp)·(η2-C60)}·(Solvent) (2). The crystal structure of 1 has been solved to show the coordination of nickel to the C–C bond of C70 at the 6–6 ring junction of η2-type to form Ni–C(C70) bonds of 1.929–1.941(2) ? length, the shortest M–C bonds among those known for η2-complexes of fullerenes C60 and C70. The length of the C–C bond to which Ni atom is coordinated (1.494(3) ?) is noticeably longer than the average length of these bonds in C70 (1.381(2) ?). Optical spectra of 1 in the IR- and UV-visible ranges have been analyzed to show the splitting of some C70 bands due to C70 symmetry lowering. The complex has a red–brown color in solution and manifests three bands in the visible range at 379, 467 and 680 nm. The solution of 1 is air sensitive since air exposure restores the color and absorption bands of the starting C70 at 383 and 474 nm.

Graphical abstract: Preparation of η2-complexes of fullerenes by reduction. Crystal structure and optical properties of {Ni(dppp)·(η2-C70)}·(C6H4Cl2)0.5
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