Synthesis, structure, and reactivity of diamidophosphine complexes of yttrium and the lanthanides

The reaction of the dilithiodiamidophosphine ligand precursor PhP(CH2SiMe2NPh)(2)Li-2(THF)(2)([NPN]Li-2(THF)(2)) with LnCl(3)(THF)(3) (Ln = Y, Sm, Ho. Yb. Lu; THF = tetrahydrofuran) in refluxing toluene generates the mononuclear complexes [NPN]LnCI(THF) in good yield. The molecular structures have been shown to be five-coordinate in the solid state and in solution. Attempts to prepare alkyl derivatives have only met with partial success; the reaction of MeMgCl with [NPN]YCl(THF) generates the partially characterized mixed-metal derivative [NPN]YMe2MgCl. The reaction with LiAlH4 results in complete ligand exchange and the formation of the tetranuclear lithium aluminum hydride derivative ([NPN]AlH2Li(THF))(2). Reduction of the lutetium derivative with KC8 and naphthalene generated the dinuclear naphthalene-bridged species {[NPN]Lu}(2)(mu-eta (4):eta (4)-C10H8) wherein each Lu centre engages in eta (4)-coordination to opposite sides of the arene moiety. X-ray crystallography was used to characterize the four complexes.