SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF MANGANESE(II) DERIVATIVES OF THE BULKY, CHELATING BIS(AMIDO) LIGANDS [(NMES)2SIME2]2- AND [DIPPNCH2CH2NDIPP]2-, THEIR NEUTRAL AMINE PRECURSORS, AND THEIR LITHIUM-SALTS (MES = 2,4,6-ME3C6H2, DIPP = 2,6-I-PR2C6H3)

The synthesis of three new bulky bidentate diamines, the compounds Me2Si(NHMes)2 (1), Mes(H)NCH2CH2N(H)Mes (2) (Mes = 2,4,6-Me3C6H2), and Dipp(H)NCH2CH2N(H)Dipp (3) (Dipp = 2,6-i-Pr2C6H3 is described. The addition of 2 equiv of n-BuLi to 1 or 3 results in almost quantitative yields of the novel dimeric solvent-free dilithium derivatives [{Li(Mes)N}2SiMe2]2 (4) and [Li(Dipp)NCH2CH2N(Dipp)Li]2 (5). The reaction of 1 with Mn{N(SiMe3)2}2 in the presence of LiN(SiMe3)2 gives the unusual product [Li(Mn{NMes}2SiMe2)2N(SiMe3)2] (6), which features a dimeric Mn salt of the dianion of 1 and, in addition, a Li+ ion sandwiched between two mesityl rings. The reaction of the bulky amine 3 affords the monomeric manganese(II) amide Mn[N(Dipp)CH2CH2N(H)Dipp]2 (7), which has a very distorted geometry at Mn as a result of the steric requirements and bonding of ligand 3. Compounds 1 and 3-7 have been characterized by X-ray crystallography. Crystallographic data with Cu K-alpha radiation (lambda = 1.541 78 angstrom) for 1 and 4-6 and Mo K-alpha radiation (lambda = 0.710 69 angstrom) for 3 and 7 at 130 K: 1, a = 16.401 (10) angstrom, b = 6.386 (2) angstrom, c = 9.244 (2) angstrom, Z = 2, orthorhombic, space group P2(1)2(1)2: 3, a = 10.968 (3) angstrom, b = 11.859 (4) angstrom, c = 20.455 (7) angstrom, alpha = 93.61 (3)-degrees, beta = 103.41 (3)-degrees, gamma = 109.22 (3)-degrees, Z = 4, triclinic, space group P1BAR; 4, a = 9.360 (3) angstrom, b = 10.052 (2) angstrom, c = 11.313 (3) angstrom, alpha = 77.08 (2)-degrees, beta = 85.49 (2)-degrees, gamma = 73.50 (2)-degrees, Z = 1, triclinic, space group P1BAR; 5, a = 12.758 (4) angstrom, b = 12.828 (5) angstrom, c = 19.085 (8) angstrom, beta = 103.23 (3)-degrees, Z = 4, monoclinic, space group P2(1)/c; 6, a = 12.918 (5) angstrom, b = 14.552 (5) angstrom, c = 13.395 (6) angstrom, beta = 90.35 (3)-degrees, Z = 2, monoclinic, space group P2(1): 7, a = 21.713 (12) angstrom, b = 13.927 (6) angstrom, c = 17.764 (11) angstrom, beta = 117.51 (4)-degrees, Z = 4, monoclinic, space group C2/c.