Solid-State ²⁹Si NMR Study of RSiSiR:  A Tool for Analyzing the Nature of the Si−Si Bond

The first solid state 29Si NMR of a disilyne, that is, RSiSiR, R = Si(CH(SiMe3)2)2(i-Pr) (1) was measured: delta11 = 364 +/- 20; delta22 = 221 +/- 16 and delta33 = -350 +/- 13; CSA = -643 ppm. These measured values as well as calculations for model disilynes strongly support the description of the Si-Si bond in bent disilynes as a triple bond, although with weakened pi-bonds and a reduced bond order of 2.6.