Synthesis and Properties of Intramolecularly Base-Stabilized (Disilanyl−silylene)ruthenium and -iron Complexes

Abstract

Photolysis of the 3-methoxytrisilanyl complex CpM(CO)2SiMe2SiMe2SiMe2OMe (1a, M = Ru; 1b, M = Fe) afforded the intramolecularly methoxy-stabilized disilanyl−silylene complex Cp(OC)M{SiMe2←O(Me)SiMe2SiMe2} (2a, M = Ru; 2b, M = Fe) as a primary product. Prolonged irradiation of the solution resulted in the decay of 2a,b with release of a dimethylsilylene moiety to give the methoxy-bridged bis(silylene) complex Cp(OC)M{SiMe2···O(Me)···SiMe2} (3a, M = Ru; 3b, M = Fe). The X-ray crystal structure analysis of 2a revealed that 2a has a five-membered chelate ring and the Ru−Si(silylene) bond (2.291(2) Å) is much shorter than the other Ru−Si bond (2.350(1) Å). It can be concluded from the bond lengths that the former possesses a partial double-bond character while the latter is a normal Ru−Si single bond. Photolysis of diisopropyl derivatives CpM(CO)2SiMe2Si i Pr2SiMe2OMe (4a, M = Ru; 4b, M = Fe) gave Cp(OC)M{SiMe2←O(Me)SiMe2Si i Pr2} (5a, M = Ru; 5b, M = Fe) exclusively, in which the positions of substituents on silicon atoms in 5a and 5b were determined by 29Si−1H COLOC and NOESY NMR spectra. A mechanism involving 1,2-migration of the methoxydisilanyl group to the metal center was suggested. Irradiation of the tetrasilanyl complex CpFe(CO)2SiMe2SiMe2SiMe2SiMe2OMe (6) caused a complicated reaction, giving at least five products having methoxy groups coordinated to silylene ligands.

Recent chemistry of the η5-cyclopentadienyl dicarbonyl iron anion

“…These researchers also prepared [156] (chloropolysilanyl)Fp complexes (Scheme 96) to convert them to the methoxy analogs for photochemical reactivity studies. Photolysis gave intramolecular base-stabilized (disilanyl-silylene) iron complexes.…”

Dichlorodiisopropylsilane

“…37 Equation 15 shows an example in which an amine is released upon cleavage. para-Bromopolystyrene (22) …”

Synthesis of Silylene and Silyl(silylene)metal Complexes

“…The photolysis of a 3‐methoxytrisilanyl complex produced methoxy‐stabilized disilanyl(silylene) complex 27 40a. Prolonged irradiation of the product gave rise to the methoxy‐stabilized bis(silylene) complex 28 (Eq.…”

“…31). However, complex 28 can revert to 27 upon the insertion of dimethylsilylene, which is photochemically generated from (SiMe 2 ) 6 40b …”