Structure and photochemistry of new base-stabilized silylene (silanediyl) complexes R2(HMPA)Si:M(CO)n of iron, chromium, and tungsten (R = tert-BuO, tert-BuS, MesO, 1-AdaO, 2-AdaO, NeopO, TritO, Me, Cl; M = Fe, n = 4; M = Cr, W, n = 5): sila-Wittig reaction of the base-free reactive intermediate [Me2Si:Cr(CO)5] with dimethyl carbonate

Synthesis of N-Heterocycle Substituted Silyl Ligands within the Coordination Sphere of Iron

“…However, the series of Fp complexes ( 4 , 6 , 7 ) exhibit no straightforward correlation with the donor strength of the ligand: the difference in chemical shift between trisubstituted 4 and disubstituted 7 (Δδ = 3.5 ppm) is smaller than that between 4 and the tris-indolyl substituted 6 (Δδ = 6.7 ppm), whereas 4 and 6 exhibit indistinguishable donor properties according to ν̃(CO). Such nonlinearity was also observed by Leis et al 79 for a range of HMPA stabilized silylene metal carbonyl complexes (M = Fe, Cr, Ru; R in SiR 2 = t BuO, t BuS, Me, Cl, 1-AdaO, 2-AdaO, NeopO, TritO, Ph). This behavior has been attributed to a combined influence of diamagnetic and paramagnetic effects on the silicon shift.…”

“…Crystals of Na- 5 suitable for X-ray crystallography were grown by slow diffusion of hexane into a solution of the complex in the presence of benzo-15-crown-5 in THF. The X-ray crystal structure reveals a trigonal bipyramidal (TBP) geometry with the −SiPyr 3 moiety in the apical position, as commonly found for analogous phosphine, (base stabilized) silylene, ,− and silyl ,, iron tetracarbonyl complexes (Figure ). The Si–Fe distance in 5 (2.2576(8) Å) is well in between the extremes, close to the mean for silyl and silylene iron tetracarbonyl complexes (2.1960 < Si–Fe < 2.3630(8), ⟨Si–Fe⟩ = 2.2663 Å) and, more generally, of Si–Fe bonds .…”

Silver‐Catalyzed Silylene Transfer

“…An example of the chemistry that these complexes can participate in is the sila-Wittig reaction [equation (7.4)]. 53 In this transformation, a metathesis occurred between the chromium silylenoid 24 and the dimethyl carbonate to afford a new Schrock carbene, 25, and the trimerized product 26. This methodology allowed access a new carbene complex that eluded previous synthetic efforts.…”

Entrapment of THF‐Stabilized Iridacyclic IrIII Silylenes from Double H−Si Bond Activation and H2 Elimination

“…Although a number of transition metal silylenes have been isolated as M−SiR 2 complexes, the electrophilicity of metal silylenes, particularly in cationic complexes, has often led to the isolation of donor–acceptor complexes M−SiR 2 ⋅ B, wherein the base B is bonded to the electrophilic Si center . The well‐documented reactivity of transition metal silylenes is often a consequence of the highly electrophilic character of the Si center, particularly in cationic complexes: reactivity towards carbonyl compounds, nitriles, alkynes, isocyanates, alkenes, and amines is well documented. Interestingly, the occurrence in catalysis of transition metal silylenes prepared by activation of hydrosilanes remains limited, whereas coinage‐metal‐mediated transfer of formal silylenes from silacyclopropanes to unsaturated organic substrates is increasingly attracting interest…”