Zinc–silylene complexes

Abstract

Reactions of the chlorosilylene [PhC(N(t)Bu)2]SiCl (SiCl) and the aryl and alkyl zincorganyls Zn(C5Me5)2, ZnPh2 and ZnEt2 resulted in the first Zn-silylene complexes. In all reactions the chlorine atom of the silylene and organic groups of the zinc atom are exchanged. By using Zn(C5Me5)2 and ZnPh2 one of the newly formed silylene coordinates to the zinc atom to give [PhC(N(t)Bu)2(η(1)-C5Me5)Si-Zn(η(2)-C5Me5)Cl] and [PhC(N(t)Bu)2PhSi-ZnPh(μ-Cl)]2, respectively. In contrast, the reaction of SiCl with ZnEt2 resulted due the reduced steric demand of the silylene in the disilylene complex [PhC(N(t)Bu)2SiEt]2ZnCl2, in which both ethyl-moieties are exchanged by chlorides and two newly formed ethyl-silylenes coordinate to the zinc atom.

Investigations of the Nature of ZnII−SiII Bonds

“…Thus, the 29 Si NMR resonances of 4 and 5 are significantly shifted downfield in comparison to 1 and 2 . However, a similar chemical shift was observed for [ L Zn(C 5 Me 5 )Cl] ( δ =60.5 ppm) …”

“…The silylene−Zn bond lengths of 1 (2.3862(11) Å) and 2 (2.4116(10) Å) are almost the same, and this suggests that the Zn−Si bond is only slightly affected by the nature of the different halides. A similar Zn−Si bond length was observed in [ L Zn(C 5 Me 5 )Cl] of (2.3750(9) Å) . The 1 H NMR spectra of 1 and 2 show typical signals for the amidinate moiety and a sharp singlet for the C 5 Me 5 unit.…”

“…One of the phenyl rings lies in the Si‐Zn‐C ipso ‐C ipso plane, and the other ring is twisted by 69.9° to this plane. The Si−Zn bond (2.4482(9) Å) is significantly shorter than that in 3 but longer than those of 1 , 2 , and [ L Zn(η 2 ‐C 5 Me 5 )Cl] . The Zn−C distances of 1.997(2) and 1.993(2) Å are slightly longer than those in solvent‐free dimeric diphenylzinc (1.941(4) Å and 1.951(5) Å).…”

“…We recently reported the reactions between {PhC(N t Bu) 2 }ClSi and the homoleptic aryl and alkyl zinc compounds Zn(C 5 Me 5 ) 2 , ZnPh 2 , and ZnEt 2 , which yielded the first silylene complex of zinc with a formal Si II −Zn II bond . However, in all reactions the chlorine atom of the silylene and the organic groups of the zinc atom are exchanged.…”

“…[11,12] We recently reported the reactions between {PhC(NtBu) 2 }ClSi and the homoleptic aryl and alkyl zinc compounds Zn(C 5 Me 5 ) 2 , ZnPh 2 ,a nd ZnEt 2 ,w hich yielded the first silylene complex of zinc with af ormal Si II ÀZn II bond. [13] However,i na ll reactions the chlorine atom of the silylene and the organic groups of the zinc atom are exchanged. On using Zn(C 5 Me 5 ) 2 and ZnPh 2 as starting materials, the newly formed silylenes coordinate to the zinc atom giving [PhC(NtBu) 2 (h 1 -C 5 Me 5 )SiZn(h 2 -C 5 Me 5 )Cl] ([LZn(h 2 -C 5 Me 5 )Cl], L = {PhC(NtBu) 2 }(C 5 Me 5 )Si), and [PhC(NtBu) 2 -PhSiZnPh(m-Cl)] 2 ,r espectively.…”