NHC Adducts of Disilylated Germylenes and Stannylenes and Their Coordination Chemistry with Group 11 Metals

Abstract

Syntheses of NHC adducts of bis[tris(trimethylsilyl)silyl]germylene and -stannylene and some structurally related cyclic disilylated stannylenes are reported. Reactions of a cyclic stannylene NHC adduct with gold and silver cyanide led to cationic metal complexes with two cyanostannyl ligands. The Ag complex decomposed 1304 further to a cyanostannide. Reactions of bis[tris(trimethylsilyl)silyl]germylene and -stannylene NHC adducts with gold and silver cyanide displayed more unusual coordination chemistry with one silyl group of the ylene unit being transferred to the group 11 metal.One particularly interesting class of compounds in this chemistry is that of heavier divalent group 14 compounds (tetrylenes). [12,13] Our own recent studies focus on silylated tetrylenes, [14][15][16][17][18][19][20][21][22][23][24][25] first examples of which were reported by Klinkhammer and Schwarz, who prepared bis[tris(trimethylsilyl)silyl]stannylene and -plumbylene. [26] While Klinkhammer found that bis[tris(trimethylsilyl)silyl]stannylene is monomeric in solution our own attempts to prepare a cyclic variation of this compound showed that dimerization occurred. [14] In order to prevent the dimerization process we carried out the preparation in the presence of triethylphosphane, which led to the formation of a stannylene base adduct. [14] Klinkhammer reported that bis[tris(trimethylsilyl)silyl]stannylene also undergoes adduct formation with phosphanes [27] and later Castel, Escudié, and co-workers demonstrated that even NHC adducts of the compound can be obtained. [28] Results and DiscussionAs mentioned, Klinkhammer already reported phosphane adduct formation of bis[tris(trimethylsilyl)silyl]stannylene. [27,29] Recently we have described synthesis and characterization of a triethylphosphane adduct [17] and also the respective trimethylphosphane adduct 2 is easily accessible from the reaction of 2 equiv. of tris(trimethylsilyl)silylpotassium (1) with SnCl 2 in the presence of PMe 3 (Scheme 1). Scheme 1. Synthesis of bis[tris(trimethylsilyl)silyl]stannylene and germylene base adducts. Journal of Inorganic and General ChemistryZeitschrift für anorganische und allgemeine Chemie www.zaac.wiley-vch.de ARTICLE Analogous reactions of 1 with SnCl 2 or GeBr 2 in the presence of 1,3,4,5-tetramethylimidazol-2-ylidene ( Me IMe) gave the respective NHC adducts 3 [25] and 4 (Scheme 1). Syntheses of the analogous 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene ( Me IPr) stannylene [28] and germylene [21] adducts were reported before. Single crystal diffraction analysis of 2 ( Figure 1) and 4 ( Figure 2) provided structural proof.

Synthesis, Structure, and Reactivity of Disiloxa[3]tetrelocenophanes

“…The Sn–C NHC bond in complex 3a is 245.7 pm, the Pb–C NHC bond in complex 3b is 258.2 pm. This is comparably long (e.g.,: {(Me 3 Si) 3 Si} 2 Sn–NHC: 228.7 pm; 35 {(Me 2 Si) 2 ((Me 3 Si) 2 Si) 2 }Sn–NHC: 229.5 pm; 35 Ter(H)Pb–NHC: 233.2 pm 36 ), but similar to what has been observed previously for stannocene carbene complexes. 33 The E–Cp bonds in complexes 3a , b are significantly elongated compared to stannocenophane 2b and plumbocenophane 2c , respectively (Table 1), which indicates a weakening of the metal Cp bonds upon coordination of NHC.…”

A High Yield Synthesis of an Octastannacubane and a Bis(silyl) Stannylene via Reductive Elimination of a Silane

“…The Si-Sn À Si bond angle (116.48) is in the range of other Lewis base coordinated silyl-substituted stannylenes. [23] The DFT calculated structure of 5 is in fair agreement with the experimental structure (see SI). The 119 Sn NMR spectrum of 5 (toluene) exhibits a signal at À417.9 ppm, upfield shifted from that of the analogous bis[tris(trimethylsilyl)silyl] stannylene-NHC Me complex (À292.7 ppm).…”

Reactivity of a gold(i)/platinum(0) frustrated Lewis pair with germanium and tin dihalides

“…Anal. calcd for C 58 H 97 AuF 6 NO 4 P 3 PtS 2 : C,45.4;H,6.4;N,0.9;S,4.2. Found: C,45.8;H,6.2;N,0.8;S,4.0.…”