The reaction of the magnesium( I ) complexes [{( ~(Ar) nacnac)Mg} _(2) ], ( ~(Ar) nacnac = HC(MeCNAr) _(2) , Ar = Dip (2,6-iPr _(2) C _(6) H _(3) ), Dep (2,6-Et _(2) C _(6) H _(3) ), Mes (2,4,6-Me _(3) C _(6) H _(2) ), Xyl (2,6-Me _(2) C _(6) H _(3) )) with fullerene C _(60) afforded a series of hydrocarbon-soluble fulleride complexes [{( ~(Ar) nacnac)Mg} _( n ) C _(60) ], predominantly with n = 6, 4 and 2. ~(13) C{ ~(1) H} NMR spectroscopic studies show both similarities ( n = 6) and differences ( n = 4, 2) to previously characterised examples of fulleride complexes and materials with electropositive metal ions. The molecular structures of [{( ~(Ar) nacnac)Mg} _( n ) C _(60) ] with n = 6, 4 and 2 can be described as inverse coordination complexes of n [( ~(Ar) nacnac)Mg] ~(+) ions with C _(60) ~( n ?) anions showing predominantly ionic metal–ligand interactions, and include the first well-defined and soluble complexes of the C _(60) ~(6?) ion. Experimental studies show the flexible ionic nature of the {( ~(Ar) nacnac)Mg} ~(+) ?C _(60) ~(6?) coordination bonds. DFT calculations on the model complex [{( ~(Me) nacnac)Mg} _(6) C _(60) ] ( ~(Me) nacnac = HC(MeCNMe) _(2) ) support the formulation as an ionic complex with a central C _(60) ~(6?) anion and comparable frontier orbitals to C _(60) ~(6?) with a small HOMO–LUMO gap. The reduction of C _(60) to its hexaanion gives an indication about the reducing strength of dimagnesium( I ) complexes.
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