Synthesis and structure of a new bulky bis-(alkoxide) ligand on a terphenyl platform.

A new sterically bulky chelating bis-(alkoxide) ligand 3,3'-([1,1':4',1''-terphen-yl]-2,2''-di-yl)bis-(2,2,4,4-tetra-methyl-pentan-3-ol), (H(2)[OO](tBu)), was prepared in a two-step process as the di-chloro-methane monosolvate, C(36)H(50)O(2)·CH(2)Cl(2). The first step is a Suzuki-Miyaura coupling reaction between 2-bromo-phenyl-boronic acid and 1,4-di-iodo-benzene. The resulting 2,2''-di-bromo-1,1':4',1''-terphenyl was reacted with (t) BuLi and hexa-methyl-acetone to obtain the desired product. The crystal structure of H(2)[OO](tBu) revealed an anti conformation of the [CPh(2)(OH)] fragments relative to the central phenyl. Furthermore, the hydroxyl groups point away from each other. Likely because of this anti-anti conformation, the attempts to synthesize first-row transition-metal complexes with H(2)[OO](tBu) were not successful.