Syntheses, structures and electrochemistry of [CuL1(LR)]BF4 [L1 = 3-{2,5-dimethoxyphenyl)-1-(2-pyridyl)pyrazole; LR = tris(3-arylpyrazolyl)hydroborate] and [CuL12][BF4]2. Effects of graphitic interactions on the stability of an aryl radical cation†