Polyazolyl Chelate Chemistry. 7.1Reactivity of the Complexes [MCl(PPh3)2{HB(pz)3}] (M = Ru, Os; pz = Pyrazol-1-yl)

Buriez, Beatrice; Burns, I.; Hill, Anthony F.; White, Andrew J. P.; Williams, David J.; Wilton‐Ely, James D. E. T.

doi:10.1021/om980937x

Cited by 77 publications

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“…[7] Characteristic attributes of allenylidene complexes include: (i) the asymmetric valence band known as the ''allenylidene stretch'', giving rise to highly intense absorption bands in their infrared spectra, (ii) low-field signals for the carbon atoms of the unsaturated ligands in their 13 C NMR spectra, [4,8] and (iii) their optical spectra, which feature two bands in the visible region. The band at lower energy is due to the forbidden HOMO Ǟ LUMO transition and so is only weak, while that at higher energy is much more intense and represents the allowed transition from the lower lying second-highest occupied molecular orbital HOMO-1.…”

Section: )]mentioning

confidence: 99%

“…All other angles between cis-disposed ligands are in the 85.0Ϫ93.8°range, while mutually trans-disposed ligands make angles of approximately 171°at the metal atom. (10) 2.032(7) P(2)ϪRuϪP(1) 99.23(6) P(1)ϪC (6) 1.835(6) P(1)ϪRuϪCl 93.83(6) P(1)ϪC (11) 1.850(7) P(2)ϪRuϪCl 93.28(6) P(2)ϪC (1) 1.807(6) P(2)ϪC (31) 1.823(6) P(2)ϪC (41) 1.862(6) [13,18,19] the nitrogen atom trans to the chloride ligand is closer to the metal center than those opposite to the π-accepting phosphane ligands. Both the cyclopentadienyl (Cp) rings of the dppf ligand are essentially planar, and the phosphorus atoms are situated in the plane of the ring to which they are attached.…”

Section: Synthesis Molecular Structures and Spectroscopic Propertiesmentioning

confidence: 99%

“…[13] We were able to obtain single crystals of the dppf-substituted congener 2b, but these gave a data set of only poor quality, preventing meaningful discussion of bond lengths and angles within the allenylidene chain. We only note that, as in the chloro precursors 1a and 1b, the RuϪP bond lengths and the PϪRuϪP angles are nearly identical for both allenylidene complexes [2.376(11) and 2.416(9) against 2.3779 (7) A plot of the structure is provided as Figure 3, while the most pertinent bond parameters are collected in Table 2.…”

Section: Synthesis Molecular Structures and Spectroscopic Propertiesmentioning

confidence: 99%

“…The isomers differ in which of the Ph or the Fc substituents points toward the Tp and the ϩ PF 6 Ϫ (2a) and its dppf analogue 2b (vide supra) crystallize with the allenylidene ligand in just this orientation. [13] Scheme 3…”

Section: Synthesis Molecular Structures and Spectroscopic Propertiesmentioning

confidence: 99%

“…We compare our results for these systems with those for the corresponding ''parent'' diphenylallenylidene complex [Tp (PPh 3 ) 2 RuϭCϭ CϭCPh 2 ] ϩ , which lacks any additional redox-active moiety, as a reference system. [13] Results and Discussion…”

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(Allenylidene)ruthenium Complexes with Redox‐Active Substituents and Ligands

et al. 2003

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, L 2 = 2 PPh 3 or 1,1Ј-bis(diphenylphosphanyl)ferrocene (dppf), R = Ph or ferrocenyl] and their spectroscopic and electrochemical characteristics. Three of these compounds possess redox-active, ferrocenebased substituents or ligands − that are oxidized at lower potentials than the ruthenium center itself − attached either to the terminal carbon atom of the allenylidene ligand or to the ruthenium atom. The Fc/Ph-substituted complexes 3a and 3b provide unique examples of hindered rotation of the allenylidene substituent around the M=C bond. For 3a (L 2 = 2 PPh 3 ), two isomers differing in the orientation of the vertically aligned, unsymmetrically substituted allenylidene ligand are discernible even at 388 K. The dppf-substituted congener 3b has the allenylidene ligand in a horizontal orientation and exhibits a rotational barrier, as determined by dynamic 31 P NMR spectroscopy, of ∆G ϶ = 47 kJ/mol at T C = 238 K. The changes in the spectroscopic and electrochemical properties upon replacement of the PPh 3 by a dppf ligand and the Ph by an Fc moiety can be explained in terms of the bonding within these systems. These effects are attenuated when the ferrocene-based redox tags are oxidized, as shown by IR and

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Section: )]mentioning

confidence: 99%

Section: Synthesis Molecular Structures and Spectroscopic Propertiesmentioning

confidence: 99%

Section: Synthesis Molecular Structures and Spectroscopic Propertiesmentioning

confidence: 99%

Section: Synthesis Molecular Structures and Spectroscopic Propertiesmentioning

confidence: 99%

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(Allenylidene)ruthenium Complexes with Redox‐Active Substituents and Ligands

et al. 2003

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Recent Developments in the Reactivity of Allenylidene and Cumulenylidene Complexes

Cadierno

Gamasa

Gimeno

2001

Eur. J. Inorg. Chem.

201

117

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Allenylidene and higher cumulenylidene complexes [M]=C(=C)n=CR1R2 (n = 1, 2, 3) have continuously gained significance in the context of transition metal carbene chemistry. Important developments which have been disclosed during the last two years are reviewed. These include a variety of stoichiometric and catalytic reactions of allenylidene complexes and their utility in organic synthesis. The related chemistry of butatrienylidene (n = 2) and pentatetraenylidene (n = 3) complexes as well as theoretical studies are also reviewed.

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