The η2 Complex of Nickel Bis(diphenylphosphanyl)propane with Fullerene: {Ni(dppp)(η2‐C60)}·(Solvent) Obtained by Reduction

Abstract

AbstractThe η2 complex of nickel bis(diphenylphosphanyl)propane with fullerene, {Ni(dppp)(η2‐C60)}·(C6H14)0.84·(C6H4Cl2)0.16 (1) (C6H14: hexane, C6H4Cl2: o‐dichlorobenzene), has been obtained by reduction of the Ni(dppp)Cl2 and C60 mixture with sodium fluorenone in o‐dichlorobenzene and slow precipitation of the single crystals by diffusion of hexane. Nickel coordinates to the 6–6 bond of C60 by η2‐coordination to form Ni–C(C60) bonds with a length of 1.948–1.951(2) Å, which are the shortest M–C bonds among known η2 complexes of fullerenes. The 6–6 bond length [1.488(3) Å] where the Ni atom is coordinated is noticeably longer than the average length of other 6–6 bonds in C60 [1.388(2) Å]. Coordination of nickel to C60 results in the splitting of two bands for two IR‐active modes of C60 into three bands, because of the lower symmetry of C60, and a noticeable shift in the F1u(4) mode of C60 to lower frequencies, as a result of π back‐donation. The dark green complex manifests two absorption bands at 664 and 890 nm in the visible range. The complex is EPR silent since only a weak narrow signal with g = 2.0000 and ΔH = 0.17 mT was found in the EPR spectrum of 1 at room temperature, which originates from about 0.1 % of spins of the total amount of C60.