Complexation of Bis(trimethylsilyl)acetylene by Decamethylhafnocene To Give the Hafnacyclopropene Cp*₂Hf(η²-Me₃SiC₂SiMe₃):  An Unusually Strong Metal−Alkyne Interaction

Abstract

The complexes Cp 2 Hf(PMe 3 )(η 2 -Me 3 SiC 2 SiMe 3 ) (3) and Cp* 2 Hf(η 2 -Me 3 SiC 2 SiMe 3 ) (4), as the first examples of welldefined hafnium alkyne complexes with a simple intact alkyne, are described; 4 displays an unusually strong interaction of the alkyne with hafnium, in comparison to analogous compounds of titanium and zirconium.

Crystal structure of 1-bis(((1R,2S,5R)-2-isopropyl-5- methylcyclohexyl)cyclopentadienyl)-1-trimethylphosphine-2,3- bis(trimethylsilyl)-1-hafnacycloprop-2-ene – hexane (1:0.5), (HfC8H18Si2)(C15H22)2(PC3H9) · 0.5C6H14

“…Such suitable systems are metallocene alkyne complexes of the type Cp* 2M(h 2 -Me 3 SiC 2 SiMe 3 )(Cp* =Cporsubstituted cyclopentadienyl; M= Ti, Zr, Hf). Until recently, the hafnocene alkyne complexes have been unknown, as the first examples were reported by our group [2]. In adifferent paper, we showed the applicability of achiral modification, namely, the menthyl substituted cyclopentadienyl ligand [3].…”

Crystal structure of bis(pentamethylcyclopentadienyl)-(4,4′-di-tert-butylbipyridyl)hafnium(IV) — hexane (1:0.5), Hf(C10H15)2(C18H24N2) · 0.5C6H14

“…Recently we reported on the synthesis of hafnocene alkyne complexes and found the alkyne to be coordinated strongly to the metal resulting in ahafnacyclopropene structure [1]. We were interested to investigate the influence of the Lewis acidic metallocene center on other substrates such as THF [2] and bipyridines.…”

Crystal structure of 1,1-bis(pentamethylcyclopentadienyl)-4,5- bis(trimethylsilyl)-1-hafnafuran-3-one, Hf(C10H15)2(Me3SiC2SiMe3CO2)

“…Titanocene and zirconocene alkyne complexes have been known for several years now, recently we have also accomplished the synthesis of first hafnocene alkyne complexes [1,2]. To investigate the reactivity of such complexes, simple reactions, e.g.…”