Bis(diisopropylamino)silylene and Its Dimer

Tsutsui, Shoichiro; Sakamoto, Kenkichi; Kira, Mitsuo

doi:10.1021/ja980008x

Cited by 99 publications

(53 citation statements)

References 24 publications

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“…In fact, until 2012 they had only been observed as transient intermediates, generally obtained under photolytic conditions and confirmed to exist on the basis of trapping experiments. Notable earlier examples include the seminal bis(tri-tert-butylsilyl) silylene, shown to exist as a triplet in the ground state on the basis of EPR investigations [80]; or the earlier reported singlet bis(diisopropylamino)silylene [81]. Other seminal examples include Mes 2 Si: [82] and Trip 2 Si: [83] which are only stable until 77 K and have been characterised by low-temperature UV-vis spectroscopy.…”

Section: Shmentioning

confidence: 99%

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

Blom

Drieß

2013

Structure and Bonding

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*2 Si: (Cp* ¼ η 5 -C 5 Me 5 ), the first isolable Si(II) compound, and later in 1994 with the discovery of the first N-heterocyclic silylene by West and Denk, heralding the beginning of a bourgeoning era in low-valent silicon chemistry. Since these and other key discoveries, massive advances have been made in understanding and elucidating the nature of these reactive compounds, and their ability, for example, to activate small molecules, or behave as ligands in transition metal complexes which can perform a variety of catalytic or stoichiometric transformations. In this chapter, recent advances in silylene chemistry will be presented, with a particular focus on developments in the last 10 years approximately. A key emphasis will rest on the reactivity of isolable silylenes, including their coordination towards metals, with respect to small molecule bond activation, and potential catalytic transformations. Although metalcoordinated silylene complexes have been shown to be catalytically useful in a variety of transformations, metal-free catalysis with silylenes is still a target.

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Section: Shmentioning

confidence: 99%

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

Blom

Drieß

2013

Structure and Bonding

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“…Facile sil-A C H T U N G T R E N N U N G ylene extrusion was previously reported from 1,1-diarylsilacyclopropenes to afford the corresponding alkynes (thermal conditions) [57,58] and from 1,1-diamino-2,3-bis(trimethylsilyl)-silacyclopropene (photochemical conditions). [59,60] Several methods can be applied to generate cyclobutadiene, as illustrated by the selected examples which involve an extrusion step from a preformed heterocyclopentadiene derivative. [61][62][63][64] NMR investigations: The identities of 6, 7 and iso-8 were confirmed by high-resolution mass spectrometry and NMR spectroscopy.…”

Section: Synthesis and Characterisation Of 21-silaporphyrinoidsmentioning

confidence: 99%

Reactivity of Silole within a Core‐Modified Porphyrin Environment: Synthesis of 21‐Silaphlorin and its Conversion to Carbacorrole

Skonieczny

Latos‐Grażyński

Szterenberg

2008

Chemistry A European J

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Condensation of 1,1-dimethyl-3,4-diphenyl-2,5-bis(p-tolylhydroxymethyl)silole with pyrrole and p-tolylaldehyde did not form the expected 21,21-dimethyl-2,3-diphenyl-5,10,15,20-tetra(p-tolyl)-21-silaporphyrin, but rather its reduced derivative, 21-silaphlorin, which contains a tetrahedrally hybridised C5 carbon atom. Attempts to trap 21-silaporphyrin resulted in the serendipitous discovery of a unique transformation of 21-silaphlorin into a non-aromatic isomer of 2,3-diphenyl-5,10,15,21-tetra(p-tolyl)-carbacorrole (iso-carbacorrole). This novel carbaporphyrinoid contains a cyclopentadiene ring embedded in a tripyrrolic framework. This transformation of 21-silaphlorin to iso-carbacorrole, carried out under oxidative conditions, involves extrusion of dimethylsilylene accompanied by migration of the C(meso)-(p-tolyl) unit to create a cyclopentadiene ring directly linked to the adjacent pyrrole through a tetrahedral carbon atom. Insertion of silver or copper ions into iso-carbacorrole gave two structurally related organometallic complexes of "true" carbacorrole in which the metal(III) ions are bound by three pyrrolic nitrogen atoms and a tetrahedrally hybridised C21 atom of the cyclopentadiene moiety. In the presence of oxygen, the silver(III) carbacorrole undergoes internal oxidation to 21-oxacorrole. The structure of silver(III) carbacorrole was determined by X-ray crystallography. The C21 atom was found to have a tetrahedral geometry. The Ag-C(sp(3)) (2.046(5) A) bond length is similar to that in silver(III) carbaporphyrinoids in which a trigonal carbon atom coordinates to the metal ion. Density functional theory was applied to model the molecular and electronic structure of 21-silaphlorin and feasible isomers of carbacorrole. The total energies (kcal mol(-1) vs. iso-carbacorrole), calculated at the B3LYP/6-31G(**)//B3LYP/6-31G(*) level for carbacorrole, iso-carbacorrole, vacataporphyrin and cyclobutadienephlorin, demonstrate the energetic preference for iso-carbacorrole.

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“…Kira and coworkers reported that photolysis of the silirene 1 afforded the diaminosilylene 2 23 . In contrast to theoretical predictions 24 -27 , the silylene 2 apparently does not undergo dimerization to afford the bridged dimer 3 as is usually preferred in the presence of electronegative substituents but rather, according to the results of variable-temperature electronic spectroscopy, furnishes the disilene 4 (equation 4) 23 .…”

Section: A Preparationmentioning

confidence: 99%