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Synthesis and Characterization of MoOI 2 (PMe 3 ) 3 and Use of MoOX 2 (PMe 3 ) 3 (X = Cl, I) in Controlled Radical Polymerization
Author(s) -
Mata José A.,
Maria Sébastien,
Daran JeanClaude,
Poli Rinaldo
Publication year - 2006
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200600156
Subject(s) - chemistry , halide , bromide , polymerization , cationic polymerization , atom transfer radical polymerization , iodide , chloroform , styrene , reaction rate constant , crystallography , medicinal chemistry , polymer chemistry , stereochemistry , polymer , inorganic chemistry , organic chemistry , kinetics , physics , quantum mechanics , copolymer
Abstract Complex MoOCl 2 (PMe 3 ) 3 smoothly reacts with NaI in acetone to produce MoOI 2 (PMe 3 ) 3 in good yields. The geometry of the compound is mer ‐ cis octahedral, that is, identical to that of the dichloride precursor, as shown by NMR spectroscopy and by an X‐ray crystallographic study. Electrochemical investigations of MoOX 2 (PMe 3 ) 3 show irreversible oxidation waves at E p,a = +0.18 and +0.39 V for X = Cl and I, respectively. A study of the halide exchange between MoOCl 2 (PMe 3 ) 3 and NaI, or between MoOI 2 (PMe 3 ) 3 and Bu 4 NCl, shows two equilibrated isomers for the mixed halide intermediate MoOICl(PMe 3 ) 3 . The diiodide complex rapidly exchanges the iodo ligands with chloride upon dissolution in chloroform at room temperature, and with bromide from (1‐bromoethyl)benzene (BEB) under more forcing conditions. The equilibrium favors the softer halide (I) on C and the harder one (Cl or Br) on Mo IV . Both oxido compounds catalyze the atom transfer radical polymerization (ATRP) of styrene in combination with the BEB initiator, yielding polymers with quite narrow molecular weight distributions (down to 1.11). The apparent polymerization rate constant is approximately doubled in the presence of 1 equiv. of the Al(O i Pr) 3 cocatalyst. On the other hand, the system is not capable of efficiently controlling the radical chain growth for methyl acrylate polymerization. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)