| Abstract
| - The crystal structure of a novel compound CuII(dNbpy)Br2 (dNbpy = 4,4‘-di(5-nonyl)-2,2‘-bipyridine), which is used in the reverse atom transfer radical polymerization, is reported. The CuII center in the complex has a distorted square planar geometry and is coordinated by two nitrogen atoms of a single dNbpy ligand (Cu−N = 2.011(7) and 2.022(7) Å) and two bromine atoms (Cu−Br = 2.3621(14) and 2.3567(13) Å). In the presence of dNbpy, CuII(dNbpy)Br2 undergoes Br substitution to form ionic [CuII(dNbpy)2Br]+[Br]-. ΔH° and ΔS° values for this equilibrium were negative and dependent on the polarity of the medium.
- The crystal structure of a novel compound CuII(dNbpy)Br2 (dNbpy = 4,4‘-di(5-nonyl)-2,2‘-bipyridine), which isused in the reverse atom transfer radical polymerization, is reported. CuII(dNbpy)Br2 crystallizes in the triclinicP1 space group with a = 12.5283(11) Å, b = 15.0256(14) Å, c = 17.7900(16) Å, α = 90.350(2)°, β = 99.360(2)°,γ = 107.937(2)°, and Z = 2. The CuII center in the complex has a distorted square planar geometry and iscoordinated by two nitrogen atoms of a single dNbpy ligand (Cu−N = 2.011(7) and 2.022(7) Å) and two bromineatoms (Cu−Br = 2.3621(14) and 2.3567(13) Å). The similarity of the absorption spectra in the solid state and insolution suggested that the geometry of the complex remained unchanged upon dissolution. In the presence ofdNbpy, CuII(dNbpy)Br2 undergoes Br substitution to form ionic [CuII(dNbpy)2Br]+[Br]-. ΔH° and ΔS° valuesfor this equilibrium were negative and dependent on the polarity of the medium. It was found that, under thetypical polymerization conditions (T ≥90 °C and the total copper concentration in the range 1.0 × 10-2−1.0 ×10-1 M), CuIIBr2 and 2 equiv of dNbpy will predominantly form the neutral CuII(dNbpy)Br2 complex. In a polarmedium under the same conditions, [CuII(dNbpy)2Br]+[Br]- is preferred.
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