Reaction of Molybdenocene and Tungstenocene Derivatives with the Divalent Silicon Species SiN^tBuCHCHN^tBu and (C₅Me₅)₂Si

Abstract

The divalent organosilicon compounds (C5Me5)2Si (Cp*2Si) and (SiLN 2) have been compared concerning their reactivity toward metallocene derivatives of molybdenum and tungsten. While Cp*2Si does not react with Cp2MH2 (M = Mo, W), either thermally or photochemically, the reaction of SiLN 2 with Cp2MH2 leads via silanediyl insertion to Cp2M(H)(SiLN 2H) (M = Mo (1a), W (1b)). Irradiation of a mixture of Cp2Mo(PEt3) and Cp*2Si yields only decomposition products, whereas photolysis of equimolar amounts of Cp2Mo(PEt3) and SiLN 2 results in the formation of the silanediyl complex Cp2Mo(SiLN 2) (2). 2 is extremely moisture sensitive and easily adds one molecule of water to yield the metallosilanol Cp2Mo(H)(SiLN 2OH) (3). 1a and 2 have been characterized by X-ray crystallography. 2 is the first molybdenum silanediyl complex with a tricoordinated silicon atom. The silicon−molybdenum interaction in 2 has to be described as a dative bond from the silicon to the metal atom.

Reactions of Hydrosilanes with Transition Metal Complexes and Characterization of the Products

“…490b thus, the likelihood of the neutral tungsten-silylene complexes catalyzing hydrosilylation of unsaturated organic molecules was considered small. 390 The reaction of the stable silylene Si[ t BuNCHdCHNBu t ] with Cp 2 MH 2 (M ) Mo, W) resulted in the expected insertion of the silylene into the M-H bond to form 372 However, with the precursor Cp 2 Mo r PEt 3 , displacement of the phosphine occurred to give the silylene complex. The Mo-Si bond in the former complex was 2.538(3) Å, which corresponds to a single bond.…”

N‐Heterocyclic Silylenes as Ligands in Transition Metal Carbonyl Chemistry: Nature of Their Bonding and Supposed Innocence

“…For the tert ‐butyl substituted NHSis t Bu 2 NHSi H2 ( I ) and t Bu 2 NHSi ( II ), several heteroleptic transition metal carbonyl complexes have been reported, namely [M(L) 2 (CO) 4 ] (M=Cr, Mo, W; L= I , t Bu 2 NHSi), [Fe( t Bu 2 NHSi)(CO) 4 ], [Ru( t Bu 2 NHSi) 2 (CO) 3 ] and [Ni(CO) 2 ( t Bu 2 NHSi) 2 ] (Scheme ) . Silylene ligated group 6 bent‐metallocene complexes [( η 5 ‐C 5 H 5 ) 2 M(H)( t Bu 2 NHSi)] (M=Mo, W) and [( η 5 ‐C 5 H 5 ) 2 Mo( t Bu 2 NHSi)] have been prepared, which were obtained by irradiation or prolonged heating of a mixture of t Bu 2 NHSi and the metallocene dihydrides [( η 5 ‐C 5 H 5 ) 2 M(H) 2 ], or from the reaction of the silylene with phosphine‐stabilized [( η 5 ‐C 5 H 5 ) 2 Mo(PEt 3 )] . Another representative of NHSi‐stabilized bent‐metallocene type complexes, and the only silylene lanthanide compound known to date, is [( η 5 ‐C 5 Me 5 ) 2 Sm( t Bu 2 NHSi)], which is seemingly not especially stable, as the silylene ligand is easily substituted by THF giving [( η 5 ‐C 5 Me 5 ) 2 Sm(THF) 2 ] …”

Synthesis and Characterization of New N‐Heterocyclic Silylazides

“…Besides reacting transition metal precursors with “free” NHSis, the most prominent path to these complexes poses ligand elimination i.e. of CO,, THF, cod (1,5‐cycloocta‐1,3‐diene), PPh 3 , and PEt 3 , . Despite these synthetic options, access to many catalytically and structurally interesting NHSi metal complexes stays concealed so far, due to their inherent instability and reactivity , .…”