Carboxysilanes and -germanes. II. Synthesis and spectral properties of triorganosilane- and triorganogermanecarboxylic acid

Abstract

Procedures for the synthesis of carboxysilanes and -germanes of the type Me,Phs-nMC02H, where M = Si and Ge and n = 0--3, and (XCeHa)sGeCOzH, where X = m-CH3, p-CH3, m-OCH3, p-OCH3, m-F, p-F, and p-CF3, by carbonation of the corresponding triorganosilyl-and triorganogermyllithium reagents are given. The spectral properties, uv, ir, and pmr, of a number of these acids and their carbon analogs are listed and discussed. The uv spectra of Me3MC02H and MeaMCOz-, n + T * transition, are interpreted in terms of inductive release by the metalloid and T ( T * --+ d ) bonding between the functional group and the metalloid.

Synthesis and Properties of Bridgehead-Functionalized Permethylbicyclo[2.2.2]octasilanes

“…The silyl carboxylate 8 and the silyl carboxylic acid 9 exhibit a continuously rising absorption below 300 nm without any detectable maxima above 205 nm, which is characteristic for related systems. 17c, 34 Obviously in these species the carboxyl n→π* absorption band that is found at 245 and 243 nm in the spectra of Me 3 SiCOOMe and Me 3 SiCOOH, 35 respectively, is completely masked by the polysilanyl absorption in the near-UV region.…”

Low‐Valent Germanylidene Anions: Efficient Single‐Site Nucleophiles for Activation of Small Molecules

“…The aforementioned observations implicate germanium as a nucleophile in the addition of CO 2 and are reminiscent of early reports on in situ prepared triorganogermanecarboxylates [64–66] . Complexes 6 are also rare examples of μ‐CO 2 ‐κ C :κ O bonding involving a heavy Group 14 element.…”

“…The aforementioned observations implicate germanium as a nucleophile in the addition of CO 2 and are reminiscent of early reports on in situ prepared triorganogermanecarboxylates. [ 64 , 65 , 66 ] Complexes 6 are also rare examples of μ‐CO 2 ‐κ C :κ O bonding involving a heavy Group 14 element. The only other crystallographically characterised example for germanium is a [4+2] cycloadduct of 1,4‐digermabenzene with CO 2 in which the two metalloid centres work in tandem as a Lewis acid and a base.…”

Experimental evidence and bond characterization of a cyclopropenylgermylene

“…THF, hexane, C 6 D 6 and tert-butyldimethylsilane were freshly distilled over potassium. Tri-tert-butylcyclopropenium tetrafluoroborate [21], tri-panisylgermane [22], and tris [o-(dimethylamino)phenyl]germane [23] were prepared according to the reported procedures.…”