Ylenes in the M^II→Si^IV (M=Si, Ge, Sn) Coordination Mode

Abstract

The reaction of the methimazolyl (mt, i.e., 2-mercapto-1-methylimidazolide) substituted silane Si(mt)(4) with SnCl(2) and GeCl(2) in dioxane affords the paddlewheel-shaped complexes [ClSi(μ-mt)(4)MCl] (M=Sn (1) and Ge (2), respectively). These compounds represent the first crystallographically characterized hexacoordinate silicon complexes comprising a Sn or Ge atom in the Si coordination sphere. An attempt to synthesize the related silicon compound 3 [ClSi(μ-mt)(4)SiCl] instead afforded the trisilane [ClSi(μ-mt)(4)Si-SiCl(3)] (3a), which provides the first crystallographic evidence for the feasibility of oligosilanes with adjacent hexacoordinate Si atoms. One of the hexacoordinate Si atoms of 3a features the unprecedented (Si(2)S(4))Si skeleton. Natural bonding orbital (NBO) analyses of compounds 1, 2, 3a (and the target compound 3) revealed characteristics of M(II)→Si(IV) (for 2 and 3) or M(I)→Si(IV) (for 3a) dative bonding in the systems with M=Si and Ge, whereas compound 1 exhibits a covalent Sn(III)-Si(III) bond.

Stannylene or Metallastanna(IV)ocane: A Matter of Formalism

“…[19] As the tin NC increases in the order 4 < 1 < 2 < 3, we observe a lower isomer shift in the same order. Whereas the mixed-valent complexes [{(RSn IV ) 2 (m-S) 2 } 3 Sn III 2 S 6 ] [20] (R = CMe 2 CH 2 COMe) and [ClSi(m-mt) 4 SnCl]·3 (dioxane) (mt = methimazolyl) [17] have isomer shifts of 2.0 mm s…”

Stannylen oder Metallastanna(IV)‐ocan – eine Sache des Formalismus

“…0.83) zwischen denen von Sn IV -Verbindungen (3: 0.57, IV: 0.68 [5] ) und der einer kürzlich veröffentlichten Sn III -Verbindung (1.16). [17] Die Variation der Sn-lokalisierten NLs von + und 8 mit ähnli-chen Pd-Sn-Koordinationssphären (Schema 5). [18] Unsere NBO-Analyse der optimierten Gasphasenstrukturen von 7 + und 8 bestätigte, dass sie 1 in ihren elektronischen Eigenschaften sehr ähnlich sind (Tabelle 2).…”

“…[19] So wie die Zinn-NL in der Reihe 4 < 1 < [20] (R = CMe 2 CH 2 COMe) und [ClSi(m-mt) 4 SnCl]·3 Dioxan [17] (mt = Methimazolyl) Isomerieverschiebungen von 2.0 mm s À1 zeigen (charakteristisch für dreiwertiges Zinn), sind die Signallagen von 4 bzw. 3 charakteristisch für Sn II -bzw.…”

Rational Syntheses and Serendipity: Complexes [LSnPtCl2(SMe2)]2, [{LSnPtCl(SMe2)}2SnCl2], [(LSn)3(PtCl2)(PtClSnCl){LSn(Cl)OH}], and [O(SnCl)2(SnL)2] with L=MeN(CH2CMe2O)2

“…[17,18,34,35,36] In order to elucidate the situation in 2, 3,a nd 6,w ep erformed DFT calculations using NBO theory. Especially when stannylenes are coordinated to Pt II centers,t he bond can be interpreted as Sn II !Pt II or as Pt 0 !…”