[MO2(MECN)8][BF4]4 SUPPORTED ON SILICA - AN EFFICIENT HETEROGENEOUS CATALYST FOR THE RING-OPENING METATHESIS POLYMERIZATION OF NORBORNEN

The dimolybdenum(II,II) complex salts [Mo2(MeCN)8][BF4]4 and [Mo2(mu-O 2CMe)2(MeCN)6][BF4]2 have been supported on silica to give materials r epresented as [Mo2(MeCN)8][BF4]4-SiO2 and [Mo2-mu-O2CMe)2(MeCN)6][BF4] 2-SiO2, respectively. Unsupported [Mo2(MeCN)8][BF4]4, [Mo2(MeCN)8][BF4 ]4-SiO2, unsupported [Mo2(mu-O2CMe)2(MeCN)6][BF4]2 and [Mo2(mu-O2CMe)2 (MeCN)6] [BF4]2-SiO2 were each tested as heterogeneous catalysts for t he ring-opening metathesis polymerization of norbornene (bicyclo[2.2.1 ]hept-2-ene). In the absence of AlEtCl2 cocatalyst [Mo2(MeCN)8] [BF4] 4-SiO2 was the only species to polymerize norbornene, and at 90-degree s-C and a reaction time of 48 h the polymerization was essentially qua ntitative. Species [Mo2(MeCN)8][BF4]4, [Mo2(mu-OCMe)2(MeCN)6][BF4]2 an d [Mo2(mu-O2CMe)2(MeCN)6] [BF4]2-SiO2 were found to be completely inac tive without AlEtCl2, even at elevated temperatures. In the presence o f AlEtCl2 cocatalyst [Mo2(MeCN)8][BF4]4-SiO2 was the only material whi ch failed to polymerize norbornene at room temperature.