Rhenium(VII) monoimido alkylidyne complexes. The importance of face selectivity in the metathesis of acetylenes via rhenacyclobutadiene intermediates
- Massachusetts Inst. of Tech., Cambridge (USA)
Re(NAr){sub 2}(CH-t-Bu)Cl (Ar = 2,6-C{sub 6}H{sub 3}-i-Pr{sub 2}) reacts with 3 equiv of HCl in diethyl ether to give (ArNH{sub 3})(Re-(C-t-Bu)(NHAr)Cl{sub 4}) (1a) as an insoluble orange powder. (NEt{sub 4})(Re(C-t-Bu)(NHAr)Cl{sub 4}) (1b) can be prepared from 1a by cation exchange. Addition of ZnCl{sub 2} to 1b yields (Re(C-t-Bu)(NHAr)Cl{sub 3}){sub 2} (2a), an x-ray study of which shows it to be a dimer in which each Re is a square pyramid with the neopentylidyne {alpha}-carbon atom in the apical position and a weakly bound bridging chloride ligand trans to it. Adducts of the type Re(C-t-Bu)(NHAr)Cl{sub 3}(L) (L = THF, py) can be prepared from 2a. Addition of DBU to Re(C-t-Bu)(NHAr)Cl{sub 3}(py) in the presence of pyridine gives Re(C-t-Bu)(NAr)Cl{sub 2}(py){sub 2} (4a). A more useful analogue, Re(C-t-Bu)(NAr)Cl{sub 2}(DME) (4b), can be prepared by adding ZnCl{sub 2} to 1b followed by NEt{sub 3} in DME. Complexes of the type Re(C-t-Bu)(NAr)(OR){sub 2} (OR = O-t-Bu (5a), OCMe{sub 2}(CF{sub 3}) (5b), O-2,6-C{sub 6}H{sub 3}-i-Pr{sub 2} (5c), OC(CF{sub 3}){sub 2}Me (5d), or OC(CF{sub 3}){sub 2}H (as a diethyl ether adduct, 5e)) can be prepared from 1b or 4b. Reactions of 5d and 5e with symmetric internal acetylenes give fluxional rhenacyclobutadiene complexes. Re(NAr)(C{sub 3}R{sub 3})(OC(CF{sub 3}){sub 2}Me){sub 2} and Re(NAr)(C{sub 3}R{sub 3})(OC(CF{sub 3}){sub 2}H){sub 2} for R = Et, n-Pr, i-Bu, and i-Pr.
- DOE Contract Number:
- FG05-86ER75292
- OSTI ID:
- 5169511
- Journal Information:
- Journal of the American Chemical Society; (United States), Journal Name: Journal of the American Chemical Society; (United States) Vol. 113:1; ISSN 0002-7863; ISSN JACSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
ACETYLENE
ALKYNES
CHEMICAL REACTION KINETICS
COMPLEXES
CRYSTAL STRUCTURE
DATA
EXPERIMENTAL DATA
HYDROCARBONS
INFORMATION
KINETICS
MEASURING METHODS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANOMETALLIC COMPOUNDS
REACTION KINETICS
RHENIUM COMPLEXES
TRANSITION ELEMENT COMPLEXES