N-Centered Hexazirconium Chloride Clusters: Excision and Redox Chemistry

The tightly cross-linked solid Zr6Cl15N yields [(Zr6NCl12)Cl6]3- upon heating with bis(triphenylphosphine)iminium
chloride (PPNCl), in MeCN at 90 °C. Purple solutions containing [(Zr6NCl12)Cl6]3- were obtained and characterized
with 15N NMR. Cyclic voltammetric (CV) measurements on the series of [(Zr6ZCl12)Cl6]n- cluster ions (Z = Be, B,
C, and N) in acetonitrile reveal that these cluster ions exhibit multiple reversible redox waves at potentials that can
be systematically understood, including a reversible redox wave corresponding to the [(Zr6NCl12)Cl6]3-/4- couple.
Preparation of the reduced cluster ion, [(Zr6NCl12)Cl6]4-, (with 15 cluster-bonding electrons) was achieved by reduction
of [(Zr6NCl12)Cl6]3- with (C5(CH3)5)2Co. Several new N-centered cluster complexes:  (PPN)3[(Zr6NCl12)Cl6]·CH2Cl2,
[(C5(CH3)5)2Co+]3[(Zr6NCl12)Cl6], and (Et4N)4[(Zr6NCl12)Cl6]·2CH3CN have been isolated and structurally characterized.