Reduction Chemistry of Bis(cyclopentadienyl) Scandium Iodides with Isocyanides: Sc(II) Complexes, Isocyanide Coupling, and Aquo Adducts

Abstract

To better define scandium(II) reduction chemistry and to study ligand effects on the hyperfine coupling to 45Sc in the EPR spectra of Sc(II) complexes, which could be useful in the design of qubits based on nd1 electronic configurations, the reduction of bis(cyclopentadienyl) scandium(III) iodide complexes in the presence of isocyanide ligands has been examined. Both pentamethyl- and tetramethylcyclopentadienyl complexes have been examined with isocyanides CNR, where R = 2,6-dimethylphenyl (Xylyl), 1-naphthyl (Naph), and 2,6-diisopropylphenyl (Dipp). The synthesis and structures of the isocyanide adducts of Sc(III) metallocene iodides, Cpx2ScI(CNR) [Cpx = C5Me5 (Cp*) and C5Me4H (Cptet)] are described as well as EPR data on the Sc(II) products formed by reduction of Cpx2ScI in the presence of CNR. A more direct synthetic route to the Sc(II) complex, Cp*2Sc(CNXylyl)2, is reported. New Sc(III) complexes obtained from these reactions are also described including [Cptet2Sc(μ-CN)]4 which is the first crystallographically characterized Sc complex containing (CN)1– cyanide ligands, as well as products with two and three coupled isocyanides, Cptet2Sc(XylylNCCNXylyl)ScCptet2, Cptet2Sc(C27N3H28), and Cpx2Sc(C33N3H22). In addition, the [Cp*2Sc(CNXylyl)2]1+ cation was isolated as the (BPh4)1– salt for comparison with the Sc(II) analog, Cp*2Sc(CNXylyl)2, and the unexpected organometallic aquo adducts, [Cptet2Sc(H2O)2][I][THF] and Cptet2Sc(OH)(H2O), were fortuitously crystallized.