OCTAHEDRAL METAL-CARBONYLS .73. DISPLACEMENT OF AROMATIC SOLVENTS (SOLV) FROM (SOLV)CR(CO)5 COMPLEXES GENERATED AFTER FLASH-PHOTOLYSIS - MODES OF BONDING AND MECHANISM

Rates of solvent displacement by 1-hexane (hex) from 17 (solv)Cr(CO)5 transients generated after pulsed laser flash photolysis (solv = aromatic solvent, C6H6-nXn; X = alkyl, perfluoroalkyl (R, Rf); F, Cl, Br; n = 0-4), (solv)Cr(CO)5 + hex → (η2-hex)Cr(CO)5 + solv, have been determined. Analyses of the rate constants in terms of the steric and electronic properties of solv indicate that the rections take place via initial slow fission of a solvCr bond. The data also indicate that for R, Rf and F substituents, solv is coordinated to Cr "edge on" via an isolated CC bond, while for solv which contain Cl and Br substituents, coordination to Cr takes place through halogenic lone pairs. Aside from influences of the mode of coordination of solv to Cr, rates increase with increasing electron-withdrawing properties and increasing steric bulk of the substituents. © 1990.