A comparison of the coordination preferences of Zn, Co, and Cd(II) with the heteroscorpionate ligand (2-hydroxy-3-t-butyl-methylphenyl)bis (3,5-dimethylpyrazolyl)methane

Abstract

Reaction of the Zn, Cd, or Co nitrate salts with the deprotonated ligand (2-hydroxy-3-t-butyl-methylphenyl)bis(3,5-dimethylpyrazolyl)methane (L1O⁻) in methanol produced the following complexes: [(L1OH)Zn(NO₃)₂] in two isomorphs, a = 40.983(8) Å, b = 9.571(2) Å, c = 15.667(8) Å, α = 90^○, β = 106.38(1)^○, γ = 90^○, C2/c, and a = 13.027(3) Å, b = 14.781(4) Å, c = 16.107(3) Å, α = 90^○, β = 105.30(1)^○, γ = 90^○, P2₁/n; [(L1OH)Cd(pz)(NO₃)₂] a = 14.7476(2) Å, b = 13.5411(2) Å, c = 16.7223(2) Å, α = 90^○, β = 110.3840(10)^○, γ = 90^○, P2₁/c; and [(L1O)Co(pz)(NO₃)] a = 11.4240(2) Å, b = 13.4498(2) Å, c = 13.8056(2) Å, α = 105.2080(10)^○, β = 105.8130(10)^○, γ = 112.7470(10)^○, P ${\bar 1}$. The Zn adopts a pseudotetrahedral four-coordinate geometry where the potentially tridentate ligand is actually bidentate with a protonated and uncoordinated phenoxy arm. The Co complex is pseudooctahedral six-coordinate where the phenoxy arm is deprotonated and coordinated. Finally the Cd complex is seven-coordinate but the metal is not coordinated through the phenoxy group that is again protonated.