Reactions of Tetraalkyldiindane(4), R2In−InR2 (R = CH(SiMe3)2), with tert-Butyl and Phenyl Isonitriles. Formation of Adducts with Retention of the In−In Bond

Tetrakis[bis(trimethylsilyl)methyl]diindane(4) ( 1 ) reacts with tert -butyl or phenyl isonitrile not by the insertion of the isonitrile carbon atom into its In−In single bond but by the formation of weak adducts with one isonitrile molecule coordinated to each of the coordinatively unsaturated In atoms. While the tert -butyl isonitrile adduct 5 is almost centrosymmetric in the solid state with the largest possible separation between the bulky tert -butyl groups, the phenyl groups are neighbored and parallel in the corresponding phenyl derivative 6 . The In−In distances of both compounds (2.8483 Å on average for 5 and 2.8482(6) Å for 6 ) are identical and only slightly lengthened compared with the starting compound 1 (2.828(1) Å).