Electronic Structure and Reactivity of a [1],[1]Disilamolybdenocenophane

Arnold, Thomas; Braunschweig, Holger; Gross, M.; Kaupp, Martin; Müller, Robert; Radacki, Krzysztof

doi:10.1002/chem.200902883

Cited by 11 publications

(9 citation statements)

References 63 publications

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“…A two-electron-reduced azobenzene is further evinced by significant elongation of the diazo moiety (N13–N13′ = 1.440(3) Å) compared to neutral cis -azobenzene (1.251 Å) and related trans -isomers . The reduction of the N–N bond in 2-AzBz is comparable to those observed in transition metal and lanthanide complexes bearing an (η 2 -1,2-RNNR) 2– unit, including Cp*WMe 3 (η 2 -MeNNMe) (1.38(1) Å), Cp 2 Zr(η 2 -PhNNPh)(NC 5 H 5 ) (1.434(4) Å), (κ 2 -(η 5 -C 5 H 4 SiMe 2 ) 2 )Mo(η 2 -PhNNPh) (1.4061(9) Å), [Cp*(THF)Sm] 2 [N 2 Ph 2 ] 2 (1.44(1) Å), and [Cp 2 (THF)Yb] 2 [N 2 Ph 2 ] 2 (1.470(6) Å) . Additionally, the N–N bond in 2-AzBz is significantly more reduced than the analogous bond in [((SiMe 2 NPh) 3 -tacn)U(η 2 -N 2 Ph 2 ) (1.353(4) Å) and Cp* 2 Sm(N 2 Ph 2 )(THF) (1.388(15) Å), both of which are characterized as containing a singly reduced, (PhNNPh) 1– , ligand.…”

Section: Resultsmentioning

confidence: 69%

Elucidating the Mechanism of Uranium Mediated Diazene N═N Bond Cleavage

et al. 2016

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Investigation into the reactivity of reduced uranium species toward diazenes has revealed key intermediates in the four-electron cleavage of azobenzene. Trivalent Tp*U(CHPh) (1a) (Tp* = hydrotris(3,5-dimethylpyrazolyl)borate) and Tp*U(2,2'-bpy) (1b) both perform the two-electron reduction of diazenes affording η-hydrazido complexes Tp*U(AzBz) (2-AzBz) (AzBz = azobenzene) and Tp*U(BCC) (2-BCC) (BCC = benzo[c]cinnoline) in contrast to precursors of the bis(Cp*) (Cp* = 1,2,3,4,5-pentamethylcyclopentadienide) ligand framework. The four-electron cleavage of diazenes to give trans-bis(imido) species was possible by using Cp*U(PDI)(THF) (3) (PDI = 2,6-((Mes)N═CMe)-CHN, Mes = 2,4,6-trimethylphenyl), which is supported by a highly reduced trianionic chelate that undergoes electron transfer. This proceeds via concerted addition at a single uranium center supported by both a crossover experiment and through addition of an asymmetrically substituted diazene, Ph-N═N-Tol. Further investigation of 3 and its substituted analogue, Cp*U(Bu-PDI)(THF) (3-Bu) (Bu-PDI = 2,6-((Mes)N═CMe)-p-C(CH)-CHN), with benzo[c]cinnoline, revealed that the four-electron cleavage occurs first by a single electron reduction of the diazene with the redox chemistry performed solely at the redox-active pyridine(diimine) to form dimeric [Cp*U(BCC)(HPDI)] (5) and Cp*U(BCC)(Bu-PDI) (6). While a transient pyridine(diimine) triplet diradical in the formation of 5 results in H atom abstraction and p-pyridine coupling, the tert-butyl moiety in 6 allows for electronic rearrangement to occur, precluding deleterious pyridine-radical coupling. The monomeric analogue of 5, Cp*U(BCC)(PDI) (7), was synthesized via salt metathesis from Cp*UI(PDI) (3-I). All complexes have been characterized by H NMR and electronic absorption spectroscopies, X-ray diffraction, and, where pertinent, EPR spectroscopy. Further, the electronic structures of 3-I, 5, and 7 have been investigated by SQUID magnetometry.

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Section: Resultsmentioning

confidence: 69%

Elucidating the Mechanism of Uranium Mediated Diazene N═N Bond Cleavage

et al. 2016

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“…In the metallo-ylidenes the values were lower with Cr (−1.0) and Si (0.88), for Mo (−0.49) and Si (0.82), and for W (−0.34) and Si (0.82) . A DFT calculation addressed the electronic nature of [1],[1]-disilamolybdenocenophane and concluded that the complex was formulated consistent with the calculation results …”

Section: Bonding and Calculationsmentioning

confidence: 99%

“…352 A DFT calculation addressed the electronic nature of [1], [1]disilamolybdenocenophane and concluded that the complex was formulated consistent with the calculation results. 404 7.2.3. Fe, Ru, Os.…”

Section: Author Informationmentioning

confidence: 99%

Reactions of Hydrosilanes with Transition Metal Complexes

2016

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This third review in a series involving reactions of hydrosilanes and transition metal complexes and characterization of the products covers the period 2009 thru 2013. After a brief discussion of other synthetic methods used for the formation of Si-TM complexes, Section 3 provides an extended discussion of the types of ligands and metal complexes used as reactants with hydrosilanes. The increase in use of pincer ligands in forming stable, isolable complexes is featured. Three tables list the complexes reported for primary, secondary, and tertiary silanes. Many reactions leading to SiTM complexes are initiated by loss of a ligand prior to oxidative addition of the hydrosilane or by a metathesis reaction. Structural data are tabulated for the isolated complexes and provide the Si-TM bond ranges for the elements in the "d" block. A major section on nonclassical (σ or agostic) complexes includes two general groupings with Si-H···TM and M-H···Si interactions. A section on solution processes identified by NMR spectroscopy is dominated by hydride exchange examples. A section on bonding outlines a unifying bonding description that has been proposed as well as calculations reported for Si-TM complexes, both real and hypothetical examples.

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“…To test the idea, we turned our attention towards the highly strained [1],[1]‐disilamolybdenocenophane ( 1 ) 9. In our hands, this particular complex proved to have three reactive centers, which are located at the central Mo and both Si atoms9, and are utilized in its reaction with tert ‐butylisonitrile to form the unprecedented ansa ‐Fischer‐type carbene complex 2 (Scheme ) 10…”

Section: Methodsmentioning

confidence: 99%