Investigations on novel tandem reaction of three components, [eta(5)-RC5H4(CO)(2)Mo](2), Ph2Te2, and Cp2TiCl2, Cp2ZrCl2, or Cp2ZrBr2. Synthesis and structural characterization of tetrakis- and bis-bridged dimolybdenum complexes (eta(5)-RC5H4Mo)(2)(mu-PhTe)(4) (R = MeCO, MeO2C, EtO2C), (eta(5)-RC5H4Mo)(2)(mu-Cl)(mu-PhTe)(3) (R = MeCO, MeO2C, EtO2C), (eta(5)-RC5H4Mo)(2)(mu-Br)(mu PhTe)(3) (R = MeO2C, EtO2C), and [eta(5)-RC5H4(CO)(2)Mo](2)(mu-PhTe)(2) (R = MeO2C, EtO2C)

While reaction of triply bonded dimers [eta(5)-RC5H4(CO)(2)Mo](2) (R = MeCO , MeO2C) with Ph-2-Te-2 in xylene at 110 degrees C and subsequent treatment with Cp2TiCl2 at reflux gives novel tetrakis-bridged complexes (eta(5)-RC5 H4Mo)(2)(mu-PhTe)(4) (1, R = MeCO; 3, R = MeO2C) and (eta(5)-RC5H4Mo)(2)(mu -Cl)(mu-PhTe)(3) (2a,b, R = MeCO; 4a,b, R = MeO2C), the dimers [eta(5)-RC5H 4(CO)(2)Mo](2) (R = MeO2C, EtO2C) reacted with Ph2Te2 and Cp2ZrCl2 or Cp2Zr Br2 under similar conditions to afford novel tetrakis-bridged complexes (et a(5)-RC5H4Mo)(2)(mu-PhTe)(4) (3, R = MeO2C; 5, R = EtO2C), (eta(5)-RC5H4Mo) (2)(mu-Cl)(mu-PhTe)(3) (4a,b, R = MeO2C; 6a,b, R = EtO2C), and (eta(5)-RC5H 4Mo)(2)(mu-Br)(mu-PhTe)(3) (7a,b, R = MeO2C; 8a,b, R = EtO2C). A possible p athway for production of such tetrakis-bridged complexes has been suggested primarily on the basis of the following facts: (i) Treatment of triply bon ded dimers [eta(5)-RC5H4(CO)(2)Mo](2) (R = MeO2C, EtO2C) with Ph2Te2 in xyl ene at 110 degrees C produces bis-bridged complexes [eta(5)-RC5H4(CO)(2)Mo] (2)(mu-PhTe)(2) (9, R = MeO2C; 10, R = EtO2C) and (ii) reaction of 9 with C p2MCl2 (M = Ti, Zr) yields tetrakis-bridged complexes 3 and 4a,b. All the n ew products 1-10 are fully characterized by elemental analysis and IR, H-1, and Te-125 NMR spectroscopies, and 4b and 9 by single-crystal X-ray diffra ction techniques.