Browsing by Author "Engelhardt, Felix"

We investigated [{(Me 2 NCH 2 ) 2 (C 4 H 2 N)}Li] 2 ( 1 ) by means of experimental charge density calculations based on the quantum theory of atoms in molecules (QTAIM) and DFT calculations using energy decomposition analysis (EDA).

The hindered reactivity of [PhP(CH2Py)(2)LiCl](2) (2) compared to the coordination behavior of the lithium chloride free ligand PhP(CH2Py)(2) (Py = 2-pyridyl) (1) could be elucidated by means of experimental electron density studies. According to the successful synthesis of metal complexes containing the dianionic Janus Head ligand [PhP(CHPy)(2)](2-), the formation and the coordination pattern of the monoanionic ligand [PhP{C(H)Py}(CH2Py)](-) was examined. The reaction of ligand 1 with n-butyllithium/PMDETA and the superbase n-butyllithium/NaOtBu, respectively, led to the alkali metal complexes [(PMDETA)Li{C(H)Py}P(CH2Py)Ph] (5) and [(PyCH2)PhP{C(H)Py}Na(Et2O)](2) (6).

N-heterocyclic olefins (NHOs), IPrCH2(1) and SIPrCH2 (2) (IPrCH2 = {N(2,6-iPr(2)C(6)H(3))CH}(2)CCH2 and SIPrCH2 = {N(2,6-iPr(2)C(6)H(3))CH2}(2)CCH2), react with HSiCl3 and afford IPrCH(SiHCl2)(3) and SIPrCH(SiHCl2) (4), respectively. Compounds 3 and 4 have been isolated in almost quantitative yield. Interestingly, treatment of the silylene IPr center dot SiCl2 with 1 also affords 3, where silylene insertion into a C-H bond is observed. Computational analysis shows a high energy barrier for silylene insertion, therefore a protonation-deprotonation mechanism is more likely.

Carbones are well established reactive intermediates and play an important role in organic synthesis, whereas the scope of borylenes is rather limited. Selective borylene insertion into a C-N bond 10 yield boryl-tunctionalized N-heterocyclic olefins (NHOs), [{N(Dipp)N(DippBH)CHCH)CCH2](2) (6) and [{N(Dipp)N(DippBPh)CHCH}CCH2][{N(Dipp)N(Dipp)N(2-iPR-6-CHMeCH2BC6H3)CHCH}CCH2] (8) (Dipp = 2,6-iPr(2)C(6)H(3)) is reported for the first time KC{, reduction of (IPrCH2)BRX2 adducts (IPrCH2 = (N(Dipp)CH)(2)CCH2; R = X = I (2); R = Ph, X = CI (4)) affords compounds 6 and 8. Surprisingly, treatment of (IPrCH2)BHCl2 (3) with KC8 yields completely unexpected diborane compound (1Pr)BH2BH2(IPr) (7). Compound 2 is unstable in THF and induces ring opening reaction to fonn the bore.nium ion [(IPrCH2)B{O(CH2)(4)I}(2)]]