N-centered hexazirconium chloride clusters: excision and redox chemistry

The tightly cross-linked solid Zr(6)Cl(15)N yields (Zr(6)NCl(12))Cl(6)](3-) upon heating with bis(triphenylphosphine)iminium chloride (PPNCl), in MeCN at 90 degrees C. Purple solutions containing (Zr(6)NCl(12))Cl(6)](3-) were obtained and characterized with (15)N NMR. Cyclic voltammetric (CV) measurements on the series of (Zr(6)ZCl(12))Cl(6)](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 (Zr(6)NCl(12))Cl(6)](3-/4-) couple. Preparation of the reduced cluster ion, (Zr(6)NCl(12))Cl(6)](4-), (with 15 cluster-bonding electrons) was achieved by reduction of (Zr(6)NCl(12))Cl(6)](3-) with (C(5)(CH(3))(5))(2)Co. Several new N-centered cluster complexes: (PPN)(3)(Zr(6)NCl(12))Cl(6)].CH(2)Cl(2), (C(5)(CH(3))(5))(2)Co(+)](3)(Zr(6)NCl(12))Cl(6)], and (Et(4)N)(4)(Zr(6)NCl(12))Cl(6)].2CH(3)CN have been isolated and structurally characterized.