- Spontaneous vs. Base-Induced Dehydrochlorination of Group 14 ortho-Carboranylamidinates
-
The reaction of the lithium ortho-carboranylamidinate Li[HL] {HL = [o-C2B10H10C(NiPr)(NHiPr)]} with ECl2R2 (E = Si, Ge, Sn, Pb; R = Cl, Me, Bu, Ph) leads to new ortho-carboranylamidinates of the group 14 elements. In the case of the heavier elements, Ge, Sn, and Pb, compounds of the composition R2ECl[HL] were obtained in a straightforward manner, where the E atom adopts trigonal-bipyramidal coordination. In the case of Si, disproportionation to R2Si[L] and H2L takes place immediately. The R2Si[L]-type compounds, in which the Si atom exhibits a tetrahedral coordination, were obtained in a targeted synthesis protocol by reaction of the doubly lithiated ligand Li2L with R2SiCl2. The heavier homologues Cl2Ge[L] and Cl2Sn[L](THF) have been obtained accordingly. In contrast, it was found that deprotonation of R2ECl[HL] to R2E[L], employing triethylamine as a base, is not appropriate. All new compounds have been characterized by single-crystal X-ray diffraction, IR spectroscopy, and NMR spectroscopy, as well as mass spectrometry.
- Harmgarth, Nicole,Liebing, Phil,F?rster, Andreas,Hilfert, Liane,Busse, Sabine,Edelmann, Frank T.
-
-
Read Online
- Bis(triethylammonium) hexachlorostannate (IV): crystal structure and hydrogen bonding
-
The crystal structure of (Et3NH)2SnCl6 at room temperature consists of a monoclinically distorted antifluorite packing of Et3NH(+) and SnCl6(2-) ions.Each anion has two cations centrosymmetrically associated with it through bifurcated hydrogen bonds to four of the Cl atoms, leaving two of the six chlorines unengaged.The bifurcation is nearly symmetric and the N-H...2Cl group is nearly planar.Infrared spectra of undeuterated and partially deuterated polycrystalline (Et3NH)2SnCl6 show that the NH stretching vibration is essentially uncoupled while the corresponding ND vibration undergoes a complex Fermi resonance resulting in a multiplet in the spectrum of even weakly deuterated material.The hydrogen bonding in (Et3NH)2SnCl6 is stronger than in the corresponding ammonium compound.A negative temperature coefficient of the NH and ND stretching frequencies is consistent with the bifurcation of the hydrogen bond.If a low-temperature transition exists, it was not evident in the NH and ND stretching absorptions.
- Knop, Osvald,Cameron, T. Stanley,James, Margaret Ann,Falk, Michael
-
p. 2550 - 2555
(2007/10/02)
-