The Concentration Control of Magnetic Fullerene C 60 •‐ Radical Anions in a Crystal Lattice of the (Bu 4 N + ) 2 {(C 60 •‐ )⋅C 6 H 4 Cl 2 } x {[CpMo(CO) 2 C 60 ] − } 2‐x (x=1, 0.74) Complexes

Interaction of the (Bu 4 N + )(C 60 •‐ ) salt with {CpMo(CO) 3 } 2 at a different molar ratio allows one to obtain isostructural (Bu 4 N + ) 2 {(C 60 •‐ )⋅C 6 H 4 Cl 2 } x {[CpMo(CO) 2 C 60 ] − } 2‐x complexes with x=1 ( 1 ) and 0.74 ( 2 ). The complexes contain the solvated C 60 •‐ radical anions and the coordination [CpMo(CO) 2 C 60 ] − anions which share one position in the crystal structure with different occupancies. Molybdenum atom coordinates by the η 2 ‐type to the 6–6 bond of C 60 in the [CpMo(CO) 2 ( η 2 ‐C 60 )] − anions. The length of the Mo−C(C 60 ) bonds is 2.241(6)‐2.244(6) Å. Optical spectrum of 1 supports the presence of uncoordinated C 60 •‐ and neutral coordinated C 60 in [CpMo(CO) 2 ( η 2 ‐C 60 )] − . Paramagnetism of C 60 •‐ in 1 provides effective magnetic moment of 1.2 μ B whereas coordination [CpMo(CO) 2 ( η 2 ‐C 60 )] − anions are diamagnetic and EPR silent. Fullerenes form closely packed double ribbons with triangular fullerene lattice. 1 shows antiferromagnetic coupling of spins with a small Weiss temperature of −7 K. That can be explained by magnetic dilution of paramagnetic C 60 •‐ species by diamagnetic [CpMo(CO) 2 ( η 2 ‐C 60 )] − anions.