A Mixed Heavier Si=Ge Analogue of a Vinyl Anion

Abstract

The versatile reactivities of disilenides and digermenide, heavier analogues of vinyl anions, have significantly expanded the pool of silicon and germanium compounds with various unexpected structural motifs in the past two decades. We now report the synthesis and isolation of a cyclic heteronuclear vinyl anion analogue with a Si = Ge bond, potassium silagermenide as stable thf-solvate and 18-c-6 solvate by the KC 8 reduction of germylene or digermene precursors. Its suitability as synthon for the synthesis of functional silagermenes is proven by the reactions with chlorosilane and chlorophospane to yield the corresponding silyl-and phosphanyl-silagermenes. X-ray crystallographic analysis, UV/Vis spectroscopy and DFT calculations revealed a significant degree of p-conjugation between N = C and Si = Ge double bonds in the title compound.

Transition-Metal Complexes of Heavier Cyclopropenes: Non-Dewar–Chatt–Duncanson Coordination and Facile Si═Ge Functionalization

“…The sum of bond angles (excluding metal coordination) in 2a (∑∠Si1 = 325.70° and ∑∠Ge1 = 343.03°) deviates substantially from the 360° expected for a π-complex according to the Dewar–Chatt–Duncanson model, indicating a major contribution of the bicyclo[1.1.0]­metallabutane-like butterfly structure to the ground state of 2a . The elongated Si1–Ge1 bond (2.397(5) Å) in 2a in comparison to SiGe doubly bonded species known in the literature (2.220–2.276 Å) further corroborates this interpretation. Accordingly, the bent-back angles θ (θ Si1 = 31.05(5)° and θ Ge1 = 25.85(3)°) are comparable to those reported for metallacyclopropane-like structures (9.2–35.1°) , and are significantly larger than those found in disilene π-complexes (4.4–9.7°) .…”

Isolation of a planar 1,2-dilithio-disilene and its conversion to a Si–B hybrid 2π-electron system and a planar tetraboryldisilene

“… 9 The Si–Si bond length of 2.223(4) Å is same as that reported for 1-magnesium-2,3-disilacyclopropene (2.223(17) Å), while the Si–Li bond length of 2.482(12) Å is remarkably shorter than those observed in contact ion pairs of silenyl lithium species. 4,10 The two five-membered diazaborolyl C 2 N 2 B planes are essentially coplanar with the BSiSi plane (the dihedral angle = 1.83°). These structural features indicate that the dilithio-diboryldisilene 2 features an ethylene-like structure.…”

Transition Metal Complexes of Heavier Vinylidenes: Allylic Coordination vs Vinylidene–Alkyne Rearrangement at Nickel

“…The thus liberated hydrogen equivalent has been transferred to the silicon center of the coordinated double bond suggesting the involvement of a CH insertion reaction during formation of 7 ( vide infra for mechanisitic considerations). The Si1–Ge1 bond of 2.329(6) Å in 7 is longer than the reported free silagermenes (2.220–2.276 Å) but shorter than that of a side-on bound hafnocene-silagermene complex (2.398 Å) and the disilagermirene-nickel complex 2 (2.397 Å) . The Si1–Ni1 bond of 2.255(7) Å is slightly shorter than that of Inoue’s aforementioned dihydodisilene–nickel complex (2.310 Å) and almost identical to that in 2 (2.269 Å) .…”