Ni-Promoted Syntheses of New 3,3′-Dichloro-5,5′-bipyrazoles and Poly(bipyrazole-5,5′-diyl)s and Isolation of Nickel Complexes Relevant to the Syntheses

摘要: Reactions of 3,5-dichloropyrazoles and 3,3′-dichloro-5,5′-bipyrazoles with zerovalent nickel complex, Ni(0)Lm, have been studied. In cases 3,5-dichloro-1,4-dimethylpyrazole 3,5-dichloro-4-methoxycarbonyl-1-methylpyrazole, only the C(5)–Cl bond two C–Cl bonds reacts Ni(0)Lm to afford novel bis(pyrazolyl)nickel(II) complexes intact C(3)–Cl in moderate yields. Treatment H2SO4 gives new dichloro monomers: 3,3′-dichloro-1,1′,4,4′-tetramethyl-5,5′-bipyrazole its 4,4′-bis(methoxycarbonyl) analogue. These undergo dehalogenative polycondensation give poly(1,1′,4,4′-tetramethyl-5,5′-bipyrazole-3,3′-diyl) (6) analogue (7), respectively. Polymer 6 is soluble formic acid, an intrinsic viscosity 39 cm3 g−1 whereas polymer 7 various organic solvents has Mn value 8800 (Mw/Mn = 1.56) as estimated from GPC. They show photoluminescent peaks at th...