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.