Spontaneous Decomposition of an Extraordinarily Twisted and Trans-Bent Fully-Phosphanyl-Substituted Digermene to an Unusual Ge I Cluster.

Ditetrelenes R 2 E=ER 2 (E=Si, Ge, Sn, Pb) substituted by multiple N/P/O/S-donor groups are extremely rare due to their propensity to disaggregate into their tetrylene monomers R 2 E. We report the synthesis of the first fully phosphanyl-substituted digermene {(Mes) 2 P} 2 Ge=Ge{P(Mes) 2 } 2 (3, Mes=2,4,6-Me 3 C 6 H 2 ), which adopts a highly unusual structure in the solid state, that is both strongly trans-bent and highly twisted. Variable-temperature 31 P{ 1 H} NMR spectroscopy suggests that 3 persists in solution, but is subject to a dynamic equilibrium between two conformations, which have different geometries about the Ge=Ge bond (twisted/non-twisted) due to a difference in the nature of their π-stacking interactions. Compound 3 undergoes unprecedented, spontaneous decomposition in solution to give a unique Ge I cluster {(Mes) 2 P} 4 Ge 4 ⋅5 CyMe (7).