Tuning the Stability and Reactivity of Metal‐bound Alkylperoxide by Remote Site Substitution of the Ligand

An alkylperoxonickel(II) complex with hydrotris(3,5‐di iso propyl‐4‐bromo‐1‐pyrazolyl)borate, [Ni II (OO t Bu)(Tp i Pr2,Br )] ( 3a ), is synthesized, and its chemical properties are compared with those of the prototype non‐brominated ligand derivative [Ni II (OO t Bu)(Tp i Pr2 )] ( 3b ; Tp i Pr2 =hydrotris(3,5‐di iso propyl‐1‐pyrazolyl)borate). Same synthetic procedures for the prototype 3b and its precursors can be employed to the synthesis of the Tp i Pr2,Br analogues. The dimeric nickel(II)‐hydroxo complex, [(Ni II Tp i Pr2,Br ) 2 (μ‐OH) 2 ] ( 2a ), can be synthesized by the base hydrolysis of the labile complexes [Ni II (Y)(Tp i Pr2,Br )] (Y=NO 3 ( 1a ), OAc ( 1a′ )), which are obtained by the metathesis of NaTp i Pr2,Br with the corresponding nickel(II) salts, and the following dehydrative condensation of 2a with the stoichiometric amount of tert ‐butylhydroperoxide yields 3a . The unique structural characteristics of the prototype 3b , that is, highly distorted geometry of the nickel center and intermediate coordination mode of the OO moiety between η 1 and η 2 , are kept in the brominated ligand analogue 3a . The introduction of the electron‐withdrawing substitutents on the distal site of Tp R affects the thermal stability and reactivity of the nickel(II)‐alkylperoxo species.