A New Class of Biomimetically Relevant “Scorpionate” Ligands. 2. The (2-Hydroxyphenyl)bis(pyrazolyl)methanes: Structural Characterization of a Series of Mono-, Di-, and Trinuclear Nickel(II) Complexes

The preparation of a new class of mixed functionality biomimetic ligand, (2-hydroxyphenyl)bis(pyrazolyl)methane, L1, (2-hydroxyphenyl)bis(3,5-dimethylpyrazolyl)methane, L2, and (2-hydroxyphenyl)bis(3-isopropylpyrazolyl)methane, L3, is described. These ligands were used to synthesize the nickel(II) complexes, [Ni(L1)2], 1·MeCN; [Ni(L2)2], 2·0.5MeOH and 2·2H2O; [Ni(μ-L2)2NiCl2], 3·2H2O and 3·2CH2Cl2; [Ni3(μ3-Cl)2(μ-L3)2(L3)(MeOH)]Cl, 4·MeOH·4H2O and 4·MeOH·1.42iPr2O; and [Ni3(μ3-OH)2(μ-L3)3][BF4], 5 and 5·2Me2CO. X-ray crystal analysis of 1−5 gave the following structural parameters:  1·MeCN, C28H25N9NiO2, triclinic, a = 10.600(3) A, b = 11.371(3) A, c = 12.194(3) A, α = 71.17(2)°, β = 94.69(2)°, γ = 83.04(2)°, space group P1, Z = 2; 2·2H2O, C34H42N8NiO4, monoclinic, a = 9.037(2) A, b = 19.272(3) A, c = 19.643(3) A, β = 94.69(2)°, space group C2/c, Z = 4; 3·2CH2Cl2, C36H42N8Cl6Ni2O2, monoclinic, a = 13.891(4) A, b = 18.188(7) A, c = 15.012(4) A, β = 92.70(2)°, space group C2/c, Z = 4; 4·MeOH·1.42iPr2O, C67...