Rhenium complexes amines

Where rhenium-catalyzed deoxydehydration has attracted a lot of interest, only two reports concerning dehydration catalyzed by rhenium complexes are noteworthy in view of their application on biomass-derived substrates. The first was published in 1996 by Zhu and Espenson and uses MTO as catalyst for the dehydration reaction of various alcohols, either aliphatic or aromatic, to obtain the corresponding olefins. Using MTO in benzene or in the alcohol itself at room temperature after 3 days gives reasonable turnovers and, in the case of benzylic alcohols, good yields. In the same paper, MTO is used for the amination, etherification, and disproportionation of alcohols, which are all reactions interesting in the viewpoint of biomass transformation [123]. 

Analogous alkoxy and aryloxyrhenium complexes do not show the same reactivity. However, Brown and Mayer discovered soon thereafter that a different rhenium complex could mediate C—O bond formation.68 Photolysis of the Re(V) complex 13 led to C—H activation and formation of a phenyl rhenium oxo, 14. Yields were improved from 30-40% to 90% upon addition of pyridine to the photolysis mixture. The role of pyridine was unclear, because other tertiary amines provided no such improvement in yield. Substituted benzenes showed a preference for para activation over meta fluorobenzene also gave a significant amount of ortho activation. 

Oxo-rhenium complexes can catalyze various OAT reactions between suitable oxo-donors (XO = sulfoxides (R2SO) tertiary amine A-oxides (R3NO) pyridine A-oxide (C5H5NO, PyO) triphenyl-phosphine, -arsine, or -stilbene oxide (R3AO) (A = P, As, Sb) peroxides (Bn OOH, H2O2) ... 

Synthesis and characterisation of the first organometallic Tc(VIII) complex [MeTcOs] is described. Its reactions with alkenes and with aromatic amine bases are different to those of the analogous rhenium complex. 25 Terminal alkynes react with [Tc(Cl)(dppe)2] to form vinylidene complexes [Tc(=C=CHR)(Cl)(dppe)2] (R = Ph, Me, Bu ). Treatment of these complexes with acid yields the respective carbyne complexes [Tc( CH2R)(Cl)(dppe)2]. The Tc-C bond lengths in these complexes vary form 1.861(9) to 1.724(7) A, 26... 

A synthetic route developed by Tsipis co-workers (201) involves the addition of electrophiles to anionic dithiocarbimato complexes of the group 10 (Vlll) elements the latter being prepared upon deprotonation of the corresponding primary amine derived dithiocarbamate complexes. In this way, Schwarz and Rauchfuss (202) also prepared the rhenium complexes [ReS(ri -S4)(S2CNMeR)] (Eq. 25). 

Kinetic studies on the reactions of primary aliphatic amines with manganese and rhenium complexes of the type trans- M CO)J-, (L = tertiary phosphine ligand) show that the reaction... 

Rhenium(VI) complexes, 4,194 alkoxides, 4,196 amides, 4,194 amines, 4,199 carboxylates, 4,199 dimethylformamide, 4,199 dioxane, 4,198 halides, 4,195,199 2-hydroxypyridine, 4,199 imides, 4,194 magnetic behavior, 1,271 mixed sulfur-nitrogen compounds, 4,196 N heterocycles, 4,199 nitrides, 4,194 oxide halides, 4, 195 oxoanions,4,196 pyridine, 4,199 sulfates, 4,198 sulfur compounds, 4,196 tellurates, 4,198... 

In a three-component reaction, a cationic platinum isocyanide complex [(Ph3P)2Pt(CNR)Cl][BF4] is reacted with a /3-bromoamine and butyl lithium to give an imidazoldin-2-ylidene complex.This transformation can be a two-component reaction if the isocyanide ligand contains already the necessary amine functionality. This was shown for chromium, molybdenum, tungsten, and rhenium carbonyls. 

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