Synthesis and Structure of Ruthenium−Silylene Complexes:  Activation of Si−Cl Bonds in N-Heterocyclic Silanes

Abstract

Ru(0) complexes of bis(imino)pyridine ligands, [eta2-N3]Ru(eta6-Ar) and {[N3]Ru}2(mu-N2), where Ar = C6H6 or C6H5Me and [N3] = 2,6-(MesN=CMe)2C5H3N, react with N-heterocyclic silicon(IV) compounds to yield Ru(II) silylene complexes of the type [N3]Ru(X)(Cl){Si(NN)} (X = H, Cl, and Si(NN) = N,N'-bis(neopentyl)-1,2-phenylenedi(amino)silylene). The activation of two groups on the silane occurs in a stepwise fashion: initial oxidative addition of a Si-X bond, followed by 1,2-migration (alpha-elimination) of the Si-Cl group to the metal. Reversible dissociation from the Ru(II) center leads to free silylene, which can be preferentially trapped with Ru(0) complexes to generate a zero-valent silylene complex, [N3]Ru(N2){Si(NN)}, which also contains a terminal dinitrogen ligand.

Synthesis of tridentate 2,6-bis(imino)pyridyl aminechlorohydro ruthenium(II) complexes: The convenient use of amine hydrochlorides to generate metal-hydride

“…The 1 H NMR spectrum of 4a in solution is consistent with the solid state structure, and exhibits four resonances determined as the imine methyls, two pairs of o-mesityl methyls, and p-mesityl methyls, consistent with mirror symmetry in the plane bisecting pyridine. A single 1 H NMR resonance for the ruthenium hydride (d À19.72, singlet) indicates a trans hydride-chloride arrangement [11,12]. A single 1 H NMR resonance for inequivalent NeCH 3 groups is observed at room temperature (d 2.25, doublet, 3 J HH ¼ 6.3 Hz), which shows that the rotation of dimethylamine ligand around RueN bond is not hindered in solution on the NMR time scale.…”

“…In particular, novel low-valent ruthenium complexes of the 2,6-bis(imino)pyridine ligands, [h 2 -N 3 ]Ru(h 6 -Ar) (1) and {[N 3 ]Ru} 2 (m-N 2 ) (2), where Ar ¼ C 6 H 6 or C 6 H 5 (CH 3 ), and [N 3 ] ¼ 2,6-(MesN]CMe) 2 C 5 H 3 N, have been synthesized and characterized ( Fig. 1) [11,12]. These low-valent Ru (0) complexes show interesting reactivities toward SieCl bond activation as a route to silyl and silylene complexes [12,13], and the coordination of other donating ligands (e.g.…”

“…1) [11,12]. These low-valent Ru (0) complexes show interesting reactivities toward SieCl bond activation as a route to silyl and silylene complexes [12,13], and the coordination of other donating ligands (e.g. CO and PR 3 ) to generate a variety of [N 3 ]Ru(II) families [11,13].…”

Sterically induced differences in N-heterocyclic carbene transition metal complexes

“…A recent search of the CCSD reveals that such a dislocation is very rare for coordinated carbene ligands and if it occurs is limited to a few pm [9,[79][80][81][82][83]. However, for the higher homologues, N-heterocyclic silylenes NHSi [84][85][86][87][88][89] and germylenes NHGe [26,90,91] the occurrence is far more frequent and appears to be the rule for annelated NHSi and NHGe. In a recent publication, Ullah et al [92].…”

The UV‐Light Initiated Reaction of Organosilanes with Tungsten Hexacarbonyl: Formation of an Organosilylene Complex and Organosilylium Salts

“…Nevertheless, UV-irradiation of Si-H containing organosilanes with transition metal compounds still is a rather fruitful methodology for the synthesis of both base-free [9][10][11][12][13][14][15][16] and base-stabilized [17][18][19] silylene complexes. Associated with this is the desire to get more insight into the mechanism of Si-H bond activation by transition metal compounds [20][21][22][23][24][25][26][27][28][29] which in turn is relevant even for the topic of C-H bond activation [30] as well as for the understanding of transition metal-catalyzed oligo-and polysilane formation [31].…”