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This paper presents the synthesis and characterization of new homoleptic lithium magnesiate reagents incorporating the silyl-substituted alkyl ligand CH2SiMe3 in the presence of a variety of Lewis base donors, namely tetrahydrofuran (THF), 1,4-dioxane, N,N,N′,N′-tetramethylethylenediamine (TMEDA), and N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA). The constitution of these bimetallic compounds has been assessed in both the solid state and solution using a combination of X-ray crystallographic studies and multinuclear NMR spectroscopy, including 1H diffusion-ordered (1H-DOSY) NMR experiments. These studies highlight the major role played by the donor molecule in controlling the structure of the complexes as well as the wide structural diversity available for these mixed-metal species ranging from discrete molecules, as found for [(PMDETA)LiMg(CH2SiMe3)3] (6), to more complex supramolecular arrangements, as in the 1D-polymeric chain [{(THF)LiMg(CH2SiMe3)3}∞] (2) or in the stoichiometrically distinct d...

First synthesized in 1976 and recently taking on a new significance as a key precursor to heterobimetallic alkali-metal-manganese(II) complexes, bis[(trimethylsilyl)methyl] manganese has been structurally characterized by X-ray crystallography. It forms a polymeric chain structure of formula [{Mn(CH2SiMe3)(2)}(infinity)], 1, in which distorted tetrahedral, spiro Mn atoms are linked together via mu(2)-bonding alkyl ligands. The structure is notable for displaying two distinct categories of Mn-C bond lengths with a mean size differential of 0.225 angstrom and for being the first fully crystallographically characterized polymeric manganese(II) dialkyl compound. Magnetic measurements of 1 indicate a surprisingly strong spin exchange coupling of J approximate to -45 cm(-1) between the manganese ions aligned along the chain. Four Lewis base complexes of bis[(trimethyl silyl)methyl] manganese have also been subjected to X-ray crystallographic studies. Previously known [TMEDA center dot Mn(CH2SiMe3)(2)], 2, and [(pyridine)(2)Mn(CH2SiMe3)(2)], 3, both adopt a simple monomeric arrangement with C2N2 distorted tetrahedral coordinations of the metal atom. Synthesized by direct addition of the Lewis base to 1, two further, new complexes, [{(dioxane)-[Mn(CH2SiMe3)(2)](2)}(infinity)], 4, and [{(dioxane)[Mn(CH2SiMe3)(2)]}(infinity)], 5, are also reported. Hemisolvate 4 displays dimeric [(Me3SiCH2)Mn(mu-CH2SiMe3)(2)Mn(CH2SiMe3)] subunits, whereas 1:1 solvate 5 consists of monomeric subunits of [{Mn(CH2SiMe3)(2)}(infinity)]; in both cases these subunits are linked together via O(CH2CH2)(2)O bridges to generate one-dimensional polymers.

No Cr-Cr bonding is found in a new type of mixed-metal ate complex having two coordinatively unsaturated but sterically saturated bisamido-monoalkyl Cr(II) groups linked via an unusual near-square-planar-coordinated K atom in the moiety of the ate, while the cationic moiety is a separated iris-tmeda solvated second potassium atom.