(η⁵-C₅Me₅)Ru(amidinate): Highly Reactive Ruthenium Complexes Formally Bearing 16 Valence Electrons Showing Signs of Coordinative Unsaturation

Novel coordinatively unsaturated ruthenium complexes, (η5-C5Me5)Ru(amidinate), were synthesized from [(η5-C5Me5)Ru(OMe)]2 and lithium amidinates, which exist as monomers in both solution and solid states and are highly reactive toward two-electron ligands

(η⁵-C₅Me₅)Ru(amidinate): Highly Reactive Ruthenium Complexes Formally Bearing 16 Valence Electrons Showing Signs of Coordinative Unsaturation

Novel coordinatively unsaturated ruthenium complexes, (η5-C5Me5)Ru(amidinate), were synthesized from [(η5-C5Me5)Ru(OMe)]2 and lithium amidinates, which exist as monomers in both solution and solid states and are highly reactive toward two-electron ligands

(η⁵-C₅Me₅)Ru(μ₂-ⁱPrNC(Me)NⁱPr)Ru(X)(η⁵-C₅Me₅): An Unusual Bonding Mode of μ₂-Amidinate Ligand Providing the First Unequivocal Evidence for Coordinating Ability of π-Conjugate Electrons of the Amidinate Ligands to Transition Metals

(η5-C5Me5)Ru(μ2-iPrNC(Me)NiPr)Ru(X)(η5-C5Me5):  An Unusual Bonding Mode of μ2-Amidinate Ligand Providing the First Unequivocal Evidence for Coordinating Ability of π-Conjugate Electrons of the Amidinate Ligands to Transition Metal

Formation of a Six-Membered Metallacycle Consisting of Iron, Carbon, Phosphorus, Boron, and Two Oxygens: The First Example of Precedence of Migratory Insertion of CO into an M−C Bond over OR Abstraction from Coordinating Phosphite by BF₃

Treatment of Cp(CO)MeFe{P(OMe)3} with BF3·OEt2 and then PPh3 gave a six-membered metallacyclic complex, Cp(PPh3)FeC(Me)OBF2OP(OMe)2, which is suggested by its NMR data and X-ray analysis to be best described as a carbene phosphite metallacycle

(η⁵-C₅Me₅)Ru(μ₂-ⁱPrNC(Me)NⁱPr)Ru(X)(η⁵-C₅Me₅): An Unusual Bonding Mode of μ₂-Amidinate Ligand Providing the First Unequivocal Evidence for Coordinating Ability of π-Conjugate Electrons of the Amidinate Ligands to Transition Metals

(η5-C5Me5)Ru(μ2-iPrNC(Me)NiPr)Ru(X)(η5-C5Me5):  An Unusual Bonding Mode of μ2-Amidinate Ligand Providing the First Unequivocal Evidence for Coordinating Ability of π-Conjugate Electrons of the Amidinate Ligands to Transition Metal

Conversion of Transition-Metal Complexes with Stannyl and Phosphenium Ligands into Those with Stannylene and Phosphine Ligands by Alkyl Migration from Sn to P

Treatment of Cp(CO)(SnMe3)Fe{PN(Me)CH2CH2NMe(OR)} (R = Me, Et) with Me3SiOSO2CF3 (TMSOTf) yields [Cp(CO)(SnMe2)Fe{PN(Me)CH2CH2NMe(Me)}]OTf (2), showing that P−OR bond cleavage and Me migration from Sn to P take place. The X-ray analysis of 2 reveals that this is a stannylene complex of iron stabilized by both an OTf- anion and an N atom in the phosphorus ligand. In solution, 2 is in equilibrium with an OTf-dissociated species

Behavior of Metallocene Olefin Polymerization Catalysts under High Pressure^†

Behavior of Metallocene Olefin Polymerization Catalysts under High Pressure†</sup

Synthesis of <i>ansa</i>-Zirconocene/Rhodium Heterobimetallic Complexes: Enhanced Catalytic Activity in Stereospecific Polymerization of α-Olefins

Novel heterobimetallic complexes that consist of zirconium and rhodium, LRh(η2-CH2CH)2Si(η5-C5H2-2,4-Me2)2ZrCl2 (3a L = η5-C9H7, 3b η5-C5H5, 3c η5-C5Me5), were synthesized, and 3b was structurally characterized. The complexes have a “C2-symmetric” ansa-zirconocene part and the rhodium metal on the bridge part. The complexes 3a−c in combination with methylaluminoxane catalyzed highly isospecific polymerization of α-olefins. Their catalytic activities were higher than that of the parent zirconocene complex, and the obtained polymer had a larger molecular weight

Comparison of the Reactivity of Cationic Phosphenium Complexes of Iron Containing a Group 14 Element Ligand

Reactions = Si (2a), Ge (3a), and Sn (4a)) with a Lewis acid (BF3·OEt2 or Me3SiOSO2CF3 (TMSOTf)) have been examined. The silyl complex 2a reacts with BF3·OEt2 to give a stable cationic phosphenium complex OMe anion abstraction from phosphorus. This reaction is in contrast to that of the corresponding alkyl complex reported earlier showing that the phosphenium complex once formed immediately undergoes migratory insertion of the phosphenium ligand into the Fe−C bond. The X-ray analysis that there is considerable double-bond character in the Fe−P bond. The rotation barrier around the Fe−P(phosphenium) bond is estimated (ΔG⧧ (248 K) = 12.7 kcal/mol) from a variable-temperature 1H NMR study. The germyl complex 3a exhibits the same reactivity as that of 2a. In contrast, the stannyl complex 4a reacts with TMSOTf to give a stannylene (4e). X-ray analysis reveals that 4e is regarded as a stannylene iron complex doubly-base-stabilized by an oxygen of OTf- and one nitrogen of ligand. In solution, there is an equilibrium between a base-stabilized and a base-free stannylene form. The activation parameter (ΔG⧧ (188 K) = 9.0 kcal/mol) is estimated for the methyl group exchange in the stannylene ligand. The reaction of TMSOTf verifies that a cationic phosphenium iron complex is formed first and that then an alkyl migration from the Sn to the phosphenium phosphorus takes place

Diastereoselective Photochromism of a Bisbenzothienylethene Governed by Steric as Well as Electronic Interactions

Introduction of an asymmetric center to C-2 of one of the benzothiophene rings of bisbenzothienylperfluorocyclopentene results in a highly diastereoselective photochromic system. The stereogenic center bears a hydrogen atom, a methyl group, and a methoxymethoxy group. The steric as well as the electronic repulsions gave an 87−88% diastereomer excess in various solvents at room temperature with 80−85% conversion to the colored form. The enantioselective synthesis was also carried out. Upon photoirradiation in hexane, a change in optical rotation at 820 nm, where neither the open form nor the colored form absorbs light, was observed repeatedly