(N2)3- Radical Chemistry via Trivalent Lanthanide Salt/Alkali Metal Reduction of Dinitrogen: New Syntheses and Examples of (N2)2- and (N2)3- Complexes and Density Functional Theory Comparisons of Closed Shell Sc3+, Y3+, and Lu3+ versus 4f9 Dy3+

New syntheses of complexes containing the recently discovered (N-2)(3-) radical trianion have been developed by examining variations on the LnA(3)/M reductive system that delivers "LnA(2)" reactivity when Ln = scandium, yttrium, or a lanthanide, M = an alkali metal, and A = N(SiMe3)(2) and C5R5. The first examples of LnA(3)/M reduction of dinitrogen with aryloxide ligands (A = OC6R5) are reported: the combination of Dy(OAr)(3) (OAr = (OC6H3Bu2)-Bu-t-2,6) with KC8 under dinitrogen was found to produce both (N-2)(2-) and (N-2)(3-) products, [(ArO)(2)Dy(THF)(2)](2)(mu-eta(2):eta(2)-N-2), 1, and [(ArO)(2)Dy(THF)](2)(mu-eta(2):eta(2)-N-2)[K(THF)(6)], 2a, respectively. The range of metals that form (N-2)(3-) complexes with [N(SiMe3)(2)](-) ancillary ligands has been expanded from Y to Lu, Er, and La. Ln[N(SiMe3)(2)](3)/M reactions with M = Na as well as KC8 are reported. Reduction of the isolated (N-2)(2-) complex {[(Me3Si)(2)N](2)Y(THF)}(2)(mu-eta(2):eta(2)-N-2), 3, with KC8 forms the (N-2)(3-) complex, {[(Me3Si)(2)N](2)Y(THF)}(2)(mu-eta(2):eta(2)-N-2)[K(THF)(6)], 4a, in high yield. The reverse transformation, the conversion of 4a to 3 can be accomplished cleanly with elemental Hg. The crown ether derivative {[(Me3Si)(2)N](2)Y(THF)}(2)(mu-eta(2):eta(2)-N-2)[K(18-crown-6)(THF)(2)] was isolated from reduction of 3 with KC8 in the presence of 18-crown-6 and found to be much less soluble in tetrahydrofuran (THF) than the [K(THF)(6)](+) salt, which facilitates its separation from 3. Evidence for ligand metalation in the Y[N(SiMe3)(2)](3)/KC8 reaction was obtained through the crystal structure of the metallacyclic complex {[(Me3Si)(2)N](2)Y[CH2Si(Me-2)NSiMe3]}[K(18-crown-6)(THF)(toluene)]. Density functional theory previously used only with reduced dinitrogen complexes of closed shell Sc3+ and Y3+ was extended to Lu3+ as well as to open shell 4f(9) Dy3+ complexes to allow the first comparison of bonding between these four metals.