Basicity of transition metal carbonyl complexes

Lokshin, B. V.; Rusach, E. B.; Kolobova, N. E.; Makarov, Yu. V.; Ustynyuk, Nikolai A.; Zdanovich, V. I.; Zhakaeva, A.Zh.; Setkina, V. N.

doi:10.1016/s0022-328x(00)92014-x

Cited by 30 publications

(10 citation statements)

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“…The symmetric A mode gives a strong band at 1928 cm −1 . In solution, the 13 C NMR signature of the carbonyl carbons of the Cr(CO) 3 moiety is a single signal at 233.6 ppm, shielded by 1.5 ppm with respect to the signal of the same ligands in reference compound 1: this spectral feature reveals the flexibility of the structure of 4 in solution in comparison to other hemichelates, for which the 13 C NMR spectra at room temperature were generally characterized by two to three broad 13 C singlets for the Cr(CO) 3 moiety. 7,8b The 13 C NMR spectrum clearly indicates that the incipient semibridging CO interaction 18 with the Pd centers visible in Figure 3 is unimportant to the dynamics of the Cr(CO) 3 moiety in solution.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…This latter property of the arene-bound Cr(CO) 3 moiety is not new; it was already underlined several decades ago by Lewis 11 and Magomedov, 12 who outlined the "Lewis-donor properties" of (η 6 -arene)tricarbonylchromium complexes. 13 Our recent efforts concentrated on validating the concept of hemichelation with a variety of Pd(II)-, Pt(II)-, and Rh(I)-based organometallic fragments, using as heteroditopic ligand the conjugated base, i.e. the anion, of a tricarbonyl(η 6 -indene)chromium derivative 7,8b or of anti-bis(tricarbonylchromium)(η 6 :η 6 -fluorene).…”

Section: ■ Introductionmentioning

confidence: 99%

“…Thermal ellipsoids are drawn at the 30% probability level with idealized positions for hydrogen atoms. Selected interatomic distances (Å) and angles (deg): C1−C1 1.518(18), C2−C1 1.506(12), C2−C3 1.316(13),…”

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confidence: 99%

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Stabilization of an Electron-Unsaturated Pd(I)–Pd(I) Unit by Double Hemichelation

et al. 2015

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The competition between conventional coordination and hemichelation of a Pd(II) center of three different palladacycles was probed by reacting the tricarbonyl(η 6 -3-phenylprop-1-enyl)chromium anion with μ-chloro-bridged palladacycles. Structural X-ray diffraction analysis indicates that the main products of the reaction are conventional (η 3 -allyl)Pd(II) complexes. The latter display significant dynamic behavior in solution, as suggested by 1 H NMR spectroscopy. According to DFT calculations this dynamic behavior can be related to conformational equilibria and to possible chemical exchanges leading to Pd(II) hemichelates. The (η 3 -allyl)Pd(II) complexes convert readily to homoleptic bischelates of Pd(II) and to a bis-hemichelate of a Pd(I)−Pd(I) unit via a reductive disproportionation reaction. The latter Pd(I)−Pd(I) complex bears structural features very similar to those of electron-saturated bis(μ-allyl)-bridged Pd(I) complexes in the literature: the Pd−Pd interaction is only weakly covalent and is dominated by noncovalent attractive interactions, as revealed by NCI analyses. The incipient covalent interaction of the Pd(I) centers with CO ligands of the Cr(CO) 3 moieties is too weak to significantly hinder the motion of the metalcarbonyl rotor in solution, which leaves each Pd center formally unsaturated with a 14-valence-electron count. DFT investigations sustained by QTAIM, NCI, ELF, and ETS-NOCV analyses suggest the predominance of noncovalent attractive forces in the stabilization of the bis(μ-allyl)-bridged Pd(I)−Pd(I) complex. ■ INTRODUCTIONThe quest for a comprehensive account of the forces that contribute to chemical bonding in transition-metal complexes containing metal−metal interactions 1 is a challenging domain of research that underwent renewed interest 2 with the recent development of theoretical methods 3 capable of accounting for nonlocal attractive interactions such as the London force 4 in large complexes (up to 120 atoms) at moderate computational cost. 5 Such new tools pave the way for a more comprehensive description of the forces that are responsible for molecular cohesion 1b,2b,c,6 and potentially allow the rational elaboration of new paradigms for coordination chemistry that can now include noncovalent attractive forces as a significant source of molecular cohesion and stability. The term hemichelation 7 is one of these new concepts that was recently proposed to define a nonclassical chelation mode of d-block transition metals by a heteroditopic ligand with which both covalent and noncovalent interactions between the ligand and a metal are central to the stabilization of the associated transition-metal complex. 8

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Stabilization of an Electron-Unsaturated Pd(I)–Pd(I) Unit by Double Hemichelation

et al. 2015

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“…Though CPK models and simple molecular mechanics calculations (Spartan) demonstrated that a three carbon spacer should allow interaction between the Lewis acidic Sn moiety and the carbonyl oxygen without undue strain, our result does not preclude the possibility of interaction in analogous complexes with different separation between the LA and the TM. It is also likely that the Lewis acidity of the organochlorostannane is insufficient to bind to the CO ligand which is presumably less basic than the ketone oxygen in the Kuivila precedent [10,13].…”

Section: Discussionmentioning

confidence: 99%

“…A metal carbonyl has been chosen because interactions between Lewis acids and the carbonyl oxygen are well documented [1,[11][12][13]. The synthetic strategy chosen is straightforward and widely variable and could be used to prepare a range of similar complexes.…”

Section: Tm-a ¼ B-lamentioning

confidence: 99%