Computational Studies of Transition Metal−Main Group Multiple Bonding

Cundari, Thomas R.

doi:10.1021/cr980406i

Cited by 163 publications

(129 citation statements)

References 86 publications

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“…[21,26] Reaction of these with either K 2 [COT] (COT = C 8 H 8 ) or the more sterically bulky Li 2 -[COT'']·1.8 THF (COT'' = 1,4-bis(trimethylsilyl)-1,3,5,7-cyclooctatetraenyl) gave products that depended critically on the exact nature of both the imido and cyclooctatetraenyl ring substituents. Addition of one equivalent of either K 2 [COT] or Li 2 [COT'']·1.8 THF to [Ti(NtBu)Cl 2 (py) 3 ] in THF at À50 8C gave a dark red solution. After standard work-up, spectroscopically clean samples of the pseudo-two-coordinate complexes [Ti(NtBu)(COT)] (1) or [Ti(NtBu)(COT'')] (2), respectively, were isolated as yellow solids [Eq.…”

Section: Introductionmentioning

confidence: 99%

Titanium Imido Complexes of Cyclooctatetraenyl Ligands

Dunn

Hazari

Jones

et al. 2005

Chemistry A European J

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Reaction of [Ti(NR)Cl2(py)3] (R=tBu or 2,6-iPr2C6H3) with K(2)[COT] (COT=C8H8) or Li2[COT''] (COT''=1,4-C8H6(SiMe3)2) gave the monomeric complexes [Ti(NR)(eta8-COT)] or [Ti(NR)(eta8-COT'')], respectively. The pseudo-two coordinate, "pogo stick" geometry for these complexes is unique in both early transition-metal and cyclooctatetraenyl ligand chemistry. In contrast, reaction of [Ti(N-2,6-Me2C6H3)Cl2(py)3] with K2[COT] gave the mu-imido-bridged dimer [Ti2(mu-N-2,6-Me2C6H3)2(eta8-COT)2]. It appears that as the steric bulk of the imido and C8 ring substituents are decreased, dimerisation becomes more favourable. Aryl imido COT complexes were also prepared by imido ligand exchange reactions between anilines and [Ti(NtBu)(eta(8)-COT)] or [Ti(NtBu)(eta(8)-COT'')]. The complexes [Ti(NtBu)(eta(8)-COT)], [Ti(N-2,6-iPr2C6H3)2(eta8-COT)] and [Ti2(mu-N-2,6-Me2C6H3)2(eta8-COT)2] have been crystallographically characterised. The electronic structures of both the monomeric and dimeric complexes have been investigated by using density functional theory (DFT) calculations and gas-phase photoelectron spectroscopy. The most striking aspect of the bonding is that binding to the imido nitrogen atom is primarily through sigma and pi interactions, whereas that to the COT or COT'' ring is almost exclusively through delta symmetry orbitals. A DFT-based comparison between the bonding in [Ti(NtBu)(eta8-COT)] and the bonding in the previously reported late transition-metal "pogo stick"complexes [Os(NtBu)(eta6-C6Me6)], [Ir(NtBu)(eta5-C5Me5)] and [Ni(NO)(eta5-C5H5)] has also been undertaken.

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Section: Introductionmentioning

confidence: 99%

Titanium Imido Complexes of Cyclooctatetraenyl Ligands

Dunn

Hazari

Jones

et al. 2005

Chemistry A European J

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“…Additionally, numerous computational studies of Schrock-and Fischer-type TM carbenes have appeared in the literature [15]. The seminal computational work on TM-carbenes is that of Taylor and Hall who discriminated the bonding in Fischer and Schrock carbene complexes as resulting from singlet and triplet coupling, respectively, of carbenes to the metal functionality [16].…”

Section: Introductionmentioning

confidence: 99%

N-heterocyclic carbenes of the late transition metals: a computational and structural database study

Baba¹,

Cundari²,

Firkin³

2005

Inorganica Chimica Acta

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“…The imidazolin-2-iminato ligands act as a 2σ-and either a 2π-or a 4π-electron donor and, in consequence, some multiple-bond character in the interaction between the nitrogen atom and the metal centre may result. [26][27][28][29][30][31] Fine-tuning of this ligand system with respect to its steric and electronic properties can be conveniently accomplished by altering the substituents to the ring. 28,30 Pioneering work related to main group metal complexes of the imidazolin-2-iminato ligand was done by Kuhn and coworkers (VII, Fig.…”

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confidence: 99%

Synthesis, characterization and reactivity of an imidazolin-2-iminato aluminium dihydride

2014

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The reaction of bis(2,6-diisopropylphenyl)imidazolin-2-imine (LH, 1) with Me 3 N·AlH 3 furnishes {μ-LAlH 2 } 2 (2). The marked tendency of 2 to release its hydride substituents is ascribed to the strong electron-donor character of the imidazolin-2-iminato ligand. This is supported by its reactivity study and DFT calculations.In fact, compound 2 was further converted with Me 3 SiOTf, Me 2 S·BH 3 , Me 2 S·BBr 3 , and BX 3 (with X = Cl, Br, and I) into {μ-LAl(H)OTf} 2 (3), {μ-LAl(BH 4 ) 2 } 2 (4), and {μ-LAlX 2 } 2 (5, X = Br; 6, X = Cl; 7, X = I), respectively.For all new aluminium complexes the formulation as dimers was evidenced by high resolution mass spectrometry, as well as single-crystal X-ray diffraction analysis. A prominent structural motif of these compounds is the square-planar four-membered Al 2 N 2 ring with two bridging bulky imidazolin-2-imino moieties. IntroductionAluminium hydrides -versatile reagents with rich chemistry For many years, chemical synthesis has been gaining immense benefit from the distinct reactivity of the aluminium-hydrogen bond. The strong need for highly selective transformations, increased focus on safety considerations, and efficiency in handling and storage are only some reasons why we find the chemically rogue parent aluminium hydride tamed into more suitable forms today. A variety of hydridoalanes has been tailored and very often reactivity adjustment is realized by steric congestion at the aluminium centre and by attaching strongly electron-donating substituents to the aluminium atom. Furthermore, hydridoalanes are used in a diverse range of applications. For instance, the hydroalumination of carbonyl 1,2 and alkyne 3-7 functionalities is a common application for this class of compounds in organic synthesis. Though the intermediate aluminium species in these reactions are often elusive, the use of aluminium hydrides such as I 8 ( Fig. 1) that bear highly sophisticated ligands grants access to all types of isolatable and well-defined model complexes. Compound I can be categorized as an aluminium dihydride and is related to the parent aluminium trihydride by replacement of one hydride for an anionic ligand. Thus, an ancillary ligand may be introduced, and yet, two reactive functional groups at the metal centre are preserved for the purpose of follow-up chemistry. The β-diketimino group, in particular, has been a key ligand to a rich chemistry of respective aluminium dihydrides. 9-12 A prominent example is II (Fig. 1), which can View Article OnlineView Journal | View Issue be used for the activation of non-polar element-element bonds as demonstrated by its conversion with elemental sulphur or selenium. 9,10 In a different field of applied science one finds chemical vapour deposition technology exploiting the thermodynamic properties of molecular aluminium hydrides for the purpose of creating composite materials. 1,13-15Aluminium hydrides are considered as fuel storagematerials with reasonable prospects in a hydrogen-based alternate energy-supply concept. 16,17 Moreover, the...

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Computational Studies of Transition Metal−Main Group Multiple Bonding

Cited by 163 publications

References 86 publications

Titanium Imido Complexes of Cyclooctatetraenyl Ligands

Titanium Imido Complexes of Cyclooctatetraenyl Ligands

N-heterocyclic carbenes of the late transition metals: a computational and structural database study

Synthesis, characterization and reactivity of an imidazolin-2-iminato aluminium dihydride

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