First Study of Metal Hybrids of Boronic Acids: Second-Sphere Coordination Networks in the Structures of 4-Carboxyphenylboronic Acid with Some Transition Metals

Metal−organic hybrids of a boronic acid (4-carboxylphenylboronic
acid) with Co(II), Mn(II), and Ni(II) salts have been reported for
the first time. In all of the complexes, there is no interaction between
the metal and boronic acid through dative bonds. Furthermore,
second-sphere coordination, along with water clusters in the form
of octamers, was observed in the absence of any other additional
ligands. However, in the presence of aza-donor molecules such
as 1,2-bis(4-pyridyl)ethane, metal ions formed coordination polymers with those ligands, replacing the second-sphere coordination.