Adding Rubidium and Cesium to the Homologous Series of Alkali Metal Compounds of (Trimethylsilyl)methanides and 2,2,6,6‐Tetramethylpiperidides

Abstract

Keywords: Alkali metals / Metalation / Rubidium / Cesium / Carbanions / N-donor ligands (Trimethylsilyl)methylrubidium [RbCH 2 SiMe 3 ] (1) and (trimethylsilyl)methylcesium [CsCH 2 SiMe 3 ] (2) were prepared by metathesis reactions of (trimethylsilyl)methyllithium [LiCH 2 SiMe 3 ] with rubidium or cesium tert-butoxide in nhexane. Both new compounds are pyrophoric powders which were characterised by NMR spectroscopy and elemental analyses. They can be used as deprotonating agents towards secondary amines such as 2,2,6,6-tetramethylpiperidine (TMPH). The resulting amides [RbTMP] (3) and [CsTMP] (4) form temperature-sensitive, n-hexane-insoluble orange solids. Treatment with the bidentate donor N,N,NЈ,NЈ-tetra- [a]

Alkali metal derivatives of an ortho-phenylene diamine

“…4 and Table 4 40 and is close to the sum of the covalent radii of cesium and nitrogen (3.03 Å). 25 As a result of the highly electropositive and polarisable nature of the large Cs + ion, complex 6 crystallises as a polymeric species, in which the coordination environment of Cs1 is supplemented by the presence of six short Cs⋯C(aryl) interactions 29 with the Ar-C centres of the sixmembered aromatic backbone of an additional PDA framework, resulting in an η 6 35 The fact that 6 crystallises as a polymeric species can be attributed to the larger radius of cesium compared to the preceding group 1 metals (Cs + 1.65; Li + 0.78, Na + 0.98, K + 1.33 Å).…”

“…The two nitrogen atoms are three-coordinate, exhibiting a distorted trigonal planar geometry (∑∠ = 360°). The Cs1-N1 bond length of 2.985(9) Å compares to that observed in the monocesium compounds, [Cs(LH 3 )( py)] n (L = calix [4]arene) [3.098( 16) Å], 24 [Cs{([Me 3 Si] 2 C)P(C 6 H 4 CH 2 NMe 2 ) 2 }(toluene)] n [3.2758(19) and 3.1039( 17) Å], 35 and the amide-bridged dimeric complex [{Cs(μ-TMP)(TMEDA)} 2 ] [Cs-N = 3.198(2) Å, TMP = 2,2,6,6-tetramethylpiperidide], 40 and is close to the sum of the covalent radii of cesium and nitrogen (3.03 Å). 25 As a result of the highly electropositive and polarisable nature of the large Cs + ion, complex 6 crystallises as a polymeric species, in which the coordination environment of Cs1 is supplemented by the presence of six short Cs⋯C (aryl) interactions 29 with the Ar-C centres of the six-membered aromatic backbone of an additional PDA framework, resulting in an η 6 -interaction [Cs1⋯C1A 3.465 (11), Cs1⋯C2A 3.548 (11), Cs1⋯C3A 3.583( 13) Å] and construction of a one-dimensional polymer.…”

Endohedral Mixed Aggregates: Sodium Alkoxide Cages with Organic or Inorganic Central Anions and Variable Hull

“…The lack of information regarding the use of trimethylsilylmethyl in alkali metal superbases is not to be confused with related reactions producing heavier alkali metal trimethylsilylmethyl congeners of sodium [NaCH 2 SiMe 3 ],[ 20 , 21 ] potassium [KCH 2 SiMe 3 ],[ 20 , 22 ] rubidium [RbCH 2 SiMe 3 ], [23] or cesium [CsCH 2 SiMe 3 ] [23] (Scheme 1 ). This approach is also applicable to neopentyl compounds of sodium [24] and potassium.…”

Gesellschaft Deutscher Chemiker Prizes and Honors

“…Klett's research is focused on the chemistry of heavier alkali‐metal alkyl compounds, in particular the interactions of these species with alkali‐metal alkoxides. He has reported in the European Journal of Inorganic Chemistry on the synthesis of (trimethylsilyl)methylrubidium and ‐cesium, and in Angewandte Chemie on the reaction of neopentyllithium with potassium tert ‐butoxide to form a Lochmann–Schlosser superbase …”