Aggregates. 2. Syntheses and Reactivities of Homo/HeteroMAAs Florence Mongin* and Anne Harrison-Marchand* Equipe Chimie et Photonique Mol eculaires, Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS-Universit e de Rennes 1, Bât. 10A, Case 1003, Campus de Beaulieu, Avenue du G en eral Leclerc, 35042 Rennes C edex, France Laboratoire COBRA de l0Universit e de Rouen, INSA de Rouen, CNRS, UMR 6014 & FR 3038, IRCOF, Rue Tesni ere, 76821 Mont St Aignan C edex, France

Mixed AggregAte (MAA): a single concept for all dipolar organometallic aggregates. 2. Syntheses and reactivities of homo/heteroMAAs.

Publisher Summary This chapter discusses the electron-transfer reactions of polynuclear organotransition metal complexes The chemistry of polynuclear organometallic complexes has become increasingly important, particularly in aiding the understanding of the relationship among structure, bonding, and reactivity A great deal of effort has been devoted to the study of linked metallocene units to probe the redox properties of compounds containing two or more identical electron-transfer sites The imido-bridged complexes are reduced in a reversible one-electron process The monoanion (E = P), prepared by sodium naphthalenide reduction of the neutral compound and isolable as a sodium salt, has an electron spin resonance (ESR) spectrum consisting of 15 triplets There is very little information available on the redox properties of organometallic clusters of the early transition metals The trinuclear carbonyls and the mixed metal clusters undergo one-electron reduction Theoretical studies have shown that the monocations of both biferrocene and bis(fulvalene)diiron show some delocalization; the latter is much more delocalized than the former

The Electron-Transfer Reactions of Polynuclear Organotransition Metal Complexes

Heavy Grignard reagents—Synthesis and reactivity of organocalcium compounds

Metal complexes of anionic 3-borane-1-alkylimidazol-2-ylidene derivatives

Three-coordinate Ti(NRAr)3 [R = C(CD3)2(CH3), Ar = C6H3Me2] was prepared in 73% yield by sodium amalgam reduction of ClTi(NRAr)3 and in 83% yield upon treatment of TiCl3(THF)3 with 3 equiv of Li(NRAr)(OEt2) in the presence of TMEDA. Ti(tBuNPh)3 was prepared similarly in 75% yield by treatment of TiCl3(THF)3 with 3 equiv of Li(tBuNPh)(OEt2) in the presence of TMEDA. Reaction of Ti(NRAr)3 with NMo(OtBu)3 in hydrocarbon solvents at −35 °C generates a thermally unstable intermediate formulated as (tBuO)3Mo[μ-N]Ti(NRAr)3, which readily loses a tert-butyl radical and isomerizes at 25 °C. Kinetics of the latter process were obtained over the temperature range 20−60 °C; the process exhibits clean first-order behavior. The following activation parameters were obtained:  ΔH⧧ = 21.4 ± 0.2 kcal mol-1 and ΔS⧧ = −3.7 ± 0.6 cal mol-1 K-1. The oxo-bridged product (tBuO)2(N)Mo[μ-O]Ti(NRAr)3 was isolated in 83% yield from this reaction. Full characterization of the latter diamagnetic complex included an X-ray crystal struc...

Assembly of Molybdenum/Titanium μ-Oxo Complexes via Radical Alkoxide C−O Cleavage

Aus R3M · THF und LiR gelingt die Synthese von Verbindungen LiMR4 · 4 THF (M = V, Cr; R = C9H11). Das thermische, magnetische und spektrale Verhalten dieser neuen metallorganischen at-Komplexe wird beschrieben. Die Zentralatome besitzen in ihnen eine verzerrt-tetraedrische Koordinationsstruktur.



Lithium Tetramesitylvanadate and -chromate



The trimesityl compounds R3M · THF and LiR react in THF solution to form the complexes LiMR4 · 4 THF (M = V, Cr; R = C9H11). Thermal, magnetical, and spectral behaviour of this new complexes is investigated. The central atoms posses a distorted tetrahedral co-ordination.

G. Kreisel

Papers

Lithium‐tetramesitylmetallate des Vanadins und Chroms