Synthesis and Structure of Digerma‐ and Distannacyclobutenes

Abstract

The (crystalline) title compound 2 is the first distannacyclobutene. Other than the corresponding germanium compounds such as 1, 2 already dissociates reversibly into the starting compounds—cycloalkyne and stannanediyl—in solution at room temperature. This is apparently due to the fact that the energy of the CSn bond is markedly less than that of the CGe bond, and can no longer compensate the ring strain.

Knüpfung von Thiostannat‐Sn‐Sn‐Bindungen in Lösung: In‐situ‐Bildung des gemischtvalenten funktionalisierten Komplexes [{(RSnIV)2(μ‐S)2}3SnIII2S6]

“…Zudem wurden anhand von subvalenten Clustern wie [Sn 9 {Sn(NR'R'')} 6 ] (R', R'' = SiMe 3 , C 6 H 3 -2,6-iPr 2 ) [4] außergewöhnliche elektronische Strukturen und eine Vielfalt möglicher Molekülstrukturen demonstriert. Ein großes Spektrum an elementorganischen Verbindungen -von Dimeren unterschiedlicher formaler Bindungsordnungen, Ladungen und Liganden, [2,5] über Ketten, [6] Cyclen [7] und Heterocyclen [8,9] zu Polycyclen [7b, 10] trug zum Verständnis von Analogien und Gegensätzen im Vergleich mit homologen Kohlenstoffverbindungen bei, etwa im Bezug auf die Reaktivität der Sn-Sn-Bindung. An die SnSn-Einheit können weitere Heteroatome gebunden sein, etwa B-Atome [11] , [11b] PAtome [12] in [{Sn(m-PCy)} 3 ] 2À [12b] oder Chalkogenatome.…”

Germanium Organometallic Compounds: Classification and Analysis of Crystallographic and Structural Data

“…The digomacycbbutene ring is planar and forms an inteplanar angle qf 5.2° with the C(1)C(2)C(3)C(6) plane. The Ge(l)-Ge(2) bond length differs little from that found in Ge^-iv tmtdi)Cl4 (238.0(1) pm) [225], but it is considerably shorter than the corresponding distance in ΰε^μ-η"-tmtdi){(NBu) 2 SiM%} 2 at 245.9(1) pm [238]. There are five digamanium derivatives which contain the Ge,X ring (X = S [223], C or Ν [224], Te [232] or Si [239]).…”

Formation and Reactions of Small Ring Compounds of Germanium and Lead

“…Recently, Veith et al and Sita et al have shown [29,30] that the formation of distannacyclobutenes does not necessarily require the presence of a distannene like 23, but can also be explained by an addition of a stannylene molecule across the carbon-carbon triple bond, followed by an insertion reaction of a second stannylene into one of the strained carbon-tin bonds [31]. MO calculations for the addition of the parent stannylene to acetylene have predicted a thermoneutral, easily reversible addition [32].…”