Synthesis, crystal structures, and redox behavior of bis(2-phenylindenyl) nickel and bis(2-phenylindenyl)zirconium dichloride

Abstract

Redox reactions of the sandwich jn5-(Ph)Ind]2Ni complex (1) (where (Ph)Ind is the 2-plrenylindenyl anion) in CH2CI2 and of the bent-sandwich (η5-(Plr)Ind]2ZrCl2 complex (2) in THF have been studied by low-temperature cyclic voltammetry. Complex ( undergoes quasi-reversible two-step oxidation to cation i+ and dication 12+, which are stable at room temperature within the cyclic voltammetry time scale. Two-electron reduction of complex 1 is irreversible up to -50 °C, and this process is accompanied by destruction of the sandwich structure of the complex. Redaction of complex 2 is described by the conventional scheme for bent-sandwich complexes. According to this scheme, further one-electron reduction of radical anion 2′- generates dianion 22−, which eliminates two CI− ions to afford bisindcnyl sandwich complex (η5-(Ph)lnd]2Zr (3). This complex is stable at T < -45 °C within the cyclic voltammetry time scale and is capable of undergoing one-electron reduction to the corresponding radical anion 3-. Synthesis and crystal structures of complexes 1 and 2 are reported.