Unsolvated “carbons apart” neodymacarborane sandwich stabilized by bis(η6-benzene)potassium cation: a unique dimeric mixed-metal sandwiched ion-pair

The reaction between NdCl3 and potassium metal in a 1:4 molar ratio in THF, followed by the addition of 2 equivalents of 1,2-(SiMe3)2-1,2-closo-C2B4H4 (1), produced the novel dimeric, mixed-metal sandwiched ion-pair, {2,2′,4,4′-(SiMe3)4-5,6-[(μ-H)2K(η6-C6H6)2]-1,1′-commo-Nd(η5-2,4-C2B4H4)2}2 (2), in 78% yield, after re-crystallization in benzene. The simultaneous cage opening/metalation product 2 was verified by single crystal X-ray diffraction.