Wilson Tam

A convenient preparation of metal carbonyl monoanions by trialkylborohydride cleavage of metal carbonyl dimers; observation and reactions of a bimetallic manganese-formyl intermediate

Commercially available Li(C2H5)3BH rapidly and quantitatively cleaves [Mn(CO)5]2, [Co(CO)4]2, and [(C5H5)Mo(CO)3]2 in THF at room temperature to the corresponding transition metal monoanions. [(C5H5)Fe(CO)2]2 can be cleaved in hexamethylphosphorous triamide (HMPA) or by use of K((unsec)-C4H9)3BH. The mechanism postulated for Li[Mn(CO)5] formation (Scheme I) is supported by the direct observation of a manganese-formyl intermediate ((un4)) and rate data. ((un4)) acts as a hydride donor toward CH3SO3F, Fe(CO)5, and HMn(CO)5.

Simplified in situ syntheses of anhydrous pentacarbonylhydromanganese

Three rapid, convenient procedures are reported for the in situ preparation of anhydrous HMn(CO)/sub 5/ in tetrahydrofuran (THF). Protonation of Li(Mn(CO)/sub 5/) in situ previously prepared by the reaction of Mn/sub 2/(CO)/sub 10/ with Li(C/sub 2/H/sub 5/)BH in THF yielded HMn(CO)/sub 5/ which was contaminated by (C/sub 2/H/sub 5/) from the preparation and by Li/sup +/CF/sub 3/SO/sub 3//sup -/ from the protonation reaction by trifluormethanesulfonic acid (CF/sub 3/SO/sub 3/H). HMn(CO)/sub 5/ free from (C/sub 2/H/sub 5/)/sub 3/B can be prepared by volatilizing the (C/sub 2/H/sub 5/)/sub 3/B along with the solvent, or alternately, the (Mn(CO))/sup -/ can be isolated as its crystalline ..mu..-nitrido-bis-(triphenylphosphorous) salt. The in situ synthesis of HMn(CO)/sub 5/ free from ionic byproducts was accomplished by the solvolysis in methanol of (CH/sub 3/)/sub 3/Si(Mn(CO)/sub 5/).

X-Ray crystal structure and chemical transformations of the neutral metal formyl [(η-C5H5)Re(PPh3)(NO)(CHO)]

The first X-ray crystallographic analysis of a metal complex containing a formyl ligand (1) and its reactions at room temperature with electrophiles and reducing agents are described.

Preparation of 2-alkyl-1,4-naphthoquinones

The reaction of 2,3-dichloro-1,4-naphthoquinone with organo aluminium, zinc, zirconium, or tin reagents yields 2-alkyl-3-chloro-1,4-naphthoquinones; with Zr or Sn reagents, palladium or nickel catalyst is needed.