Characterization of a stable (.eta.3-indenyl)iron metalate, (.eta.3-C9H7)Fe(CO)3-. A role for .eta.3-.eta.5 indenyl ligand tautomerization during alkyl-CO insertion reactions

Abstract

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Palladium-Assisted Formation of Carbon−Carbon Bonds. 5.1 Reactions of (o-Styrylaryl)palladium Complexes with Alkynes. Synthesis of Palladium Complexes with Highly Functionalized Indenyl Ligands. Crystal and Molecular Structures of (1-Benzyl-2,3-diphenyl-5,6,7-trimethoxyindenyl)- and (1-Benzyl-3-phenyl-5,6,7-trimethoxyindenyl)palladium(II) Complexes

“…However, these differences are not sufficient to allow the coordination to be described as simply η 3 . Thus, the ΔMC values (difference between the average of the metal carbon distances to the “allyl” and “ene” carbons) 14,29 0.35 and 0.39 Å lie between those expected for an η 3 (0.5−0.9 Å) and those expected for an η 5 - coordination (0−0.2 Å). ,, The same occurs with the slip angles ψ (the angles between the normal to the plane through the metal atom and the centroid−metal vector) 14,29,30c (12.7, 12.4°), which lie between the corresponding values observed in η 3 - (or η 3 -C 5 H 5 ) (20−24°) and η 5 -complexes (2−5°). ,30c However, whereas the fold angles (dihedral angles between the plane defined by the three allylic carbons and that formed by the benzenoid carbons) 9 (7, 10°) are in the range corresponding to η 5 -complexes (7.4−10°; the η 3 -complexes show values of 20−26°),30c the slip distortions , Δ (distance between the C 5 ring centroid and the projection of the metal atom on the ring) 14,29,30c (0.44, 0.39 Å), are near to the lowest limit of 0.3 Å proposed for an η 3 -coordination . In addition, C−C bond distances within the allylic and benzenoid fragments (C(1−3), C(11)/(12), respectively) are significantly shorter than the bonds between them (see figure captions), which supports an η 3 -coordination.…”

Ligand-Induced Ring Slippage of η6- to η4-Naphthalene. Preparation and Structural Characterization of Ru(η4-C10H8)(η4-1,5-C8H12)(L) [L = PMe3, PEt3, P(OMe)3] and of Derived Binuclear Complexes Containing Bridging Naphthalene, Ru2(μ-η6:η4-C10H8)(η4-1,5-C8H12)2(L) [L = PEt3

“…Some exceptions to this behavior are known, two of which occur with electron-rich complexes of later transition elements similar to the naphthalene complexes reported here. Thus, coordinated cyclooctene is displaced from Ir(η 5 -C 9 H 7 )(C 8 H 14 ) 2 by ligands L(PMe 3 ,PMe 2 Ph) to give Ir(η 3 -C 9 H 7 )L 3 , and [Fe(η 5 -C 9 H 7 )(CO) 2 ] - adds CO to give [Fe(η 3 -C 9 H 7 )(CO) 3 ] - . A few cases are known involving compounds of the earlier transition elements, e.g., the reaction of V(η 5 -C 9 H 7 ) 2 with CO to give V(η 5 -C 9 H 7 )(η 3 -C 9 H 7 )(CO) 2 , and of [M(η 5 -C 9 H 7 )(CO) 2 L 2 ] + (M = Mo, W; L = NCMe, HCONMe 2 ) with an excess of L or other N-donors to give [M(η 3 -C 9 H 7 )(CO) 2 L 3 ] + ; the last reaction appears not to occur with π-acceptor ligands such as isocyanides or tertiary phosphines …”

Structurally-Responsive Ligands for High-Performance Catalysts

“…Thus, the indenyl ligand was proposed to slip to the η 3 mode to permit binding of L, followed by migratory insertion to give the product with η 5 -Ind. The validity of the η 3 -Ind binding mode − and intermediate structures between the two binding extremes were subsequently confirmed with a number of transition metals.…”