Structure, Optical, and Magnetic Properties of (PPN+)2(C702−)⋅2 C6H4Cl2, which Contains Dianionic Polymeric (C702−)n Chains

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Abstract

A new salt, (PPN+)2(C702−)2 C6H4Cl2 (1), which contains C702− dianions, has been obtained as single crystals (PPN+=bis(triphenylphosphine)iminium cation). The C702− dianions form polymeric zigzag (C702−)n chains, in which the fullerene units are bonded through single C[BOND]C bonds of length 1.581(5)–1.586(6) Å. The distance between the centers of neighboring C702− units is 10.441 Å. The optical and magnetic properties of (C702−)n have also been studied. Decreasing the symmetry of C70 in the polymer activate about 20 new IR bands in addition to the 10 IR-active bands of the starting C70. The polymeric structure shows absorptions in the visible and NIR regions, with three main bands at 890, 1200, and 1550 nm, instead of one band of isolated C702− dianions at 1165–1184 nm. We concluded that the (C702−)n polymer was diamagnetic, with a negative molar magnetic susceptibility of −3.82×10−4 emu mol−1 per C702− dianion. The polymer is EPR silent and a weak narrow EPR signal in salt 1 is due to impurities, which only constitute 0.84 % of spin S=1/2 of the total amount of fullerene C70.

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