Crystal Structures of (Tris(trimethylsilyl)methyl)- and (Tris(dimethylphenylsilyl)methyl)potassium

Abstract

Crystals of (RMe2Si)&K (R = Me, 1; R = Ph, 2), obtained from MeK and (RMezSi)&H, contain linear chains of alternate potassium cations and planar [(RMe&)&]-anions, with weak interactions between chains; in 1 the central carbon atoms of the anions are midway between the potassium cations, but in 2 cationanion pairs are linked by q6 coordination of phenyl groups.Methylpotassium has been carefully studied by X-ray powder methods and neutron diffraction,lJ but as far as we are aware there has hitherto been nosinglecrystal X-ray investigation of 4 donor-free organopotassium compound. We report the preparation and structures of compounds 1 and 2, which contain bulky organosilyl groups. (Me,Si),CK (PhMe,Si),CK 1 2 compound 1 can be obtained by either of the routeslf The colorless, exceedingly air-and moisture-sensitive +MeLi +KOBut -MeH -LiOBut (Me,Si),CH -(Me,Si),CLi -1 (a) +MeLi +(Messi)sCH -LiOBut -MeH

Silylanions: Inversion Barriers and NMR Chemical Shifts

“…In sharp contrast to the α ‐silyl‐substituted carbanions, which are almost planar,51, 52 none of our silyl anion minima exhibits planar or even near planar geometry. The bond angle sums range from 284.7–292.9°.…”

Influence of aromatic ring substituents and co-ligand on the binding mode of a phosphine–borane-stabilized carbanion; crystal structures of [[(Me3Si)2{Ph2P(BH3)}C]KLn]2[Ln=(OEt2)2, pmdeta; pmdeta=N,N,N′,N″,N″-pentamethyldiethylenetriamine]

“…Calc. for C 27 H 51 BKO 2 PSi 2 (544.74): C,59.53;H,9.44. Found: C,59.39;H,: d 0.20 (s, 18H, SiMe 3 ), 0.65 (d,J PH = 14.0 Hz,3H,BH 3 ), 0.99 (t, 4H, CH 2 CH 3 ), 3.15 (q, 2H, OCH 2 CH 3 ), 6.99 (m,2H,7.10 (m,4H,mPh),7.94 (m,4H, Crystal structure determinations of 2a and 2b: Measurements were made at 150 K on a Bruker AXS SMART CCD diffractometer using graphite-monochromated MoKa radiation (k = 0.71073 Å ).…”

Potassium–Alkane Interactions within a Rigid Hydrophobic Pocket

“…In particular, the intramolecular K-C methyl distances K(2)-C(56) and K(1)-C(76) are 3.180(3) and 3.230(3) , respectively. For comparison, the intramolecular K-CHR 3 interactions in the sterically encumbered [{KSi-(SiMe 3 ) 3 } 2 ], [16] [KC(SiMe 3 ) 3 ] n , [18] and [K 2 (O{SiMe 2 C-(SiHMe 2 ) 2 }] n [19] range from 3.138(3) to 3.433(3) . To further probe the disposition of the K 2 (XAT) moiety to interact with the hydrocarbon solvent, alternative crystallization conditions were explored, yielding X-ray quality crystals (5), and [K 2 (XAT){(Me 3 Si) 2 O} 2 ] (6) (Scheme 1 and Figure 2).…”