Synthesis and Characterization of the Ferrio-Substituted Silicon(II) Compound Me₅C₅(CO)₂FeSiC₅Me₅

Abstract

Reaction of the (pentamethylcyclopentadienyl)silicon cation with the (pentamethylcyclopentadienyl)dicarbonylferrate anion leads to the formation of the crystalline, thermolabile silicon(II) compound [(η 5 -pentamethylcyclopentadienyl)dicarbonylferrio](η 3 -pentamethylcyclopentadienyl)silicon. The singlet-triplet energy difference ΔE ST is calculated to be 25.4 kcal/mol.

A Theoretical Study of the Half-Sandwich Silicon(II) Cation [(Me5C5)Si]+ and of the Cationic Complex [(Me5C5)Si (DME)]+

“…The calculated shifts neglecting bulk and solvent effects are in good agreement with the experimental NMR data measured in CD 2 Cl 2 solution [3,12]. Unusual highfield shifts in heteronuclear NMR spectroscopy are typical of the presence of π-complexes with main-group elements as central atoms [24].…”

“…In addition, the synthesis of the first stable compound containing a cationic silicon(II) centre was successful employing the π-bonded pentamethylcyclopentadienyl ligand. The preparation of a salt containing the halfsandwich type cation [(Me 5 C 5 )Si] + and the only weakly nucleophilic anion [B(C 6 F 5 ) 4 ] -was reported only recently [3]. The bonding in the cation is qualitatively described on the basis of the electron counting rules developed by Wade [4], Williams [5] and Rudolph [6]; this species corresponds to a nido-cluster featuring a three-dimensional aromaticity [7].…”

Recent Advances in Silylene Chemistry: Small Molecule Activation En-Route Towards Metal-Free Catalysis

“…The X-ray structural investigation revealed again a bent geometry on the silicon(II) centre and additionally confirmed the η 2 -coordination of the Cp * ring, based on the bond distances ( Fig. 15 In 2010, Jutzi and co-workers also reported facile entry to an interesting ferriosubstituted silylene using 107 as starting material [104]. Reaction of 107 with Na [Fe(η 5 -C 5 Me 5 )(CO) 2 ] in hexane afforded, by salt metathesis reaction, the complex Fe(η 5 -C 5 Me 5 )(CO) 2 {Si(η 3 -C 5 Me 5 )} (110) as a brown solid in 48% yield (Scheme 36).…”

Mono- and Polynuclear Boron Dications

“…Like in the transition-metal complexes, where the hapticity changes of Cp* play a pivotal role in stabilizing metal centers with various oxidation states and coordination numbers, the flexibility of Cp* to adjust its coordination number is found to be critical in achieving the reactive boron dications (Scheme 3). In fact, the η 5 -coordination of Cp* to main-group metals has led to the isolation of several low-valent main-group complexes, such as silyliumylidene, 39,40 silylene 41 and the related heavier group 14 analogues. 42 The incorporation of Cp* also allows the isolation of hypercoordinated borinium cations 4345 and borylenes.…”

“…In the case of alkyl isonitriles, the liberation of alkyl radicals from CN bond cleavage produces the isolated cyano-substituted boronium [40][BF 4 ]. In the presence of phenyl isonitrile, however, the second addition of isonitrile to [42] + …”