Silylated Group 14 Ylenes: An Emerging Class of Reactive Compounds

Abstract

Silyl‐substituted heavy‐element tetrylenes are very reactive entities and therefore prefer variously to dimerize to heavy olefin analogues, to oligomerize to cyclic products, or to undergo some type of rearrangement reaction. Our work on the synthesis of oligosilanyl‐substituted plumbylenes, stannylenes, and germylenes has shown that trapping such tetrylenes as phosphine adducts is a good method for preventing dimerization or rearrangement and allows the chemistry of the free tetrylene to be studied either through phosphane abstraction or even through thermally induced dissociation. In addition to a number of typical reactions with these tetrylenes, which occur in such a way that the divalent element becomes tetravalent, it was found in the case of germylenes that addition of monosubstituted alkynes proceeds by insertion into a Ge–Si bond with preservation of the divalent state of the germylene. The obtained tetrylene phosphane adducts could also be used as precursors for the generation of transition‐metal complexes with tetrylene ligands.

Alkyne Addition and Insertion Reactions of [(Me3Si)3Si]2Ge⋅PMe3

“…[4,5] Recently,w er eported the synthesis of the PMe 3 adduct of bis[tris(trimethylsilyl)silyl]germylene( 2a). [6] Ap articularly interesting property of 2a is its ability to react with phenylacetylene by insertion of the alkyne into an SiÀGe bond.Arelated alkynei nsertion into ad iborylstannylene was later reported by Protchenko et al [7] Ar ecentr eport of similar reactivity describesa lkene insertion into the SiÀSi-bond [8] of the stable acyclic silylene dipp(Me 3 Si)NÀSiÀSi(SiMe 3 ) 3 (dipp = 2,6-iPr 2 C 6 H 3 ). [9] Examples of alkyne insertion into the SnÀPa nd GeÀPb onds of stannylene/germylene-phosphinea dducts were reported by Wesemann and co-workers.…”

“…In particular, numerous applications have been found for N‐heterocyclic carbenes (NHCs). However, heavier tetrylenes (silylenes, germylenes, stannylenes, and plumbylenes) are also attractive compounds with respect to the development of novel chemistry …”

“…However,h eaviert etrylenes (silylenes, germylenes, stannylenes, and plumbylenes) are also attractive compoundsw ith respect to the development of novel chemistry. [1][2][3] One of the intriguing aspectso ft etrylenes is that despite being main-groupc ompounds they possess certainc haracteristics thus far only considered typicalf or transition-metalc omplexes. [4,5] Usuallyg roup 14 elements-such as carbon, silicon, and germanium-exhibitapronouncedt endencyf or the tetravalent state.…”

“…[14] However,r ecently NHC adducts of at ris(trimethylsilyl)silylchlorogermylene and bis[tris(trimethylsilyl)stannyl]germylene were reported. [15] Based on initial studies with cyclic disilylated stannylenes [16] and plumbylenes, [17] our work included PEt 3 and PMe 3 adducts of some cyclic disilylatedg ermylenes [18][19][20][21] and the recent synthesis of PMe 3 and NHC adducts of bis[tris(trimethylsilyl)silyl]germylene. [6] The synthesis of 2a,w hich is the PMe 3 adduct of bis[tris(trimethylsilyl)silyl]germylene 2,was accomplished in astraightforward way by reaction of tris(trimethylsilyl)silylpotassium (1) with GeCl 2 ·dioxane in the presence of PMe 3 (Scheme1).…”

Cationic Si−H−Si Bridges in Polysilanes: Their Detection and Targeted Formation in Stable Ion Studies

“…In detail, according to isodesmic reaction (), the cyclic cation 6 is more stable than dimethylsilylium, Me 2 Si + −H, by Δ E =141 kJ mol −1 (at the M06‐2X/6‐311+G(d,p) level of theory). Moreover, in the past, the 1,1,4,4‐tetrakis(trimethylsilyl)tetrasilane‐1,4‐diyl unit proved to be a well‐suited scaffold for the steric protection of reactive main group centers …”