Synthesis and characterization of an unsolvated dimeric diarylmagnesium compound and its magnesium iodide byproducts.

The Grignard reagent 2,6-Et(2)C(6)H(3)MgI(THF)(n), 1, undergoes rapid aryl exchange in THF solution at room temperature to afford the diorganomagnesium compound (2,6-Et(2)C(6)H(3))(2)Mg(THF)(n), 2, and the sparingly soluble salt Mg(THF)(6)I(2), 5. Removal of the coordinated THF in 2 under reduced pressure and elevated temperature affords the unique diorganomagnesium species [2,6-Et(2)C(6)H(3)Mg(mu-C(6)H(3)Et(2)-2,6)](2), 3, which features three-coordinate magnesium. Compound 3 is fluxional in benzene or toluene solution at room temperature and dissociates into monomeric (2,6-Et(2)C(6)H(3))(2)Mg around 115 degrees C. Recrystallization of crude 5 from benzene solution gave large well-shaped crystals of MgI(2)(THF)(3), 4, and 5. Benzene solutions of 4 and 5 are remarkably easily oxidized by laboratory air to MgI(THF)(5)I(3), 6. Compound 3 has been characterized by variable-temperature (1)H NMR spectroscopy and X-ray crystallography, and compounds 4-6 have been characterized by X-ray crystallography.

Reaction of m-terphenyldichlorophosphanes with sodium azide: synthesis and characterization of stable azidocyclophosphazenes.

Reaction of the m-terphenyldichlorophosphanes 2,6-(2-MeC(6)H(4))(2)C(6)H(3)PCl(2) (1), 2,6-(4-t-BuC(6)H(4))(2)C(6)H(3)PCl(2) (2), or 2,6-Mes(2)C(6)H(3)PCl(2) (3) with excess NaN(3) in acetonitrile at room temperature afforded the corresponding bisazidophosphanes 2,6-(2-MeC(6)H(4))(2)C(6)H(3)P(N(3))(2), 2,6-(4-t-BuC(6)H(4))(2)C(6)H(3)P(N(3))(2) (5), or 2,6-Mes(2)C(6)H(3)P(N(3))(2) (6) (Mes = 2,4,6-Me(3)C(6)H(2)), respectively. These compounds are thermally labile and decompose into a number of azidophosphazenes. The azidocyclophosphazenes [NP(N(3))(C(6)H(3)(4-t-BuC(6)H(4))(2)-2,6)](3) (4) and [NP(N(3))C(6)H(3)Mes(2)-2,6](2) (8) have been isolated from these mixtures. All compounds were characterized by (1)H, (13)C, (31)P NMR and IR spectroscopy. Crystal structures of 2, 4, and 8 were determined.

Novel aluminum hydride derivatives from the reaction of H(3)Al.NMe(3) with the cyclosilazanes.

The amine hydrogen atoms of the cyclic trimeric silazane [Me(2)SiNH](3) are readily replaced by the H(2)Al. NMe(3) group in a simple aminolyis reaction of [Me(2)SiNH](3) with H(3)Al.NMe(3) to afford the aluminum amides (Me(2)SiNAlH(2).NMe(3))(n)(Me(2)SiNH)(3-n) (1, n = 3; 2, n = 1; 4, n = 2). The monosubstituted amide 2 could not be isolated, because it undergoes condensation to the tricyclic compound 1,1',2,2'-(HAlNMe(3))(2) (3). Contrary to these results the analogous reactions of the more flexible cyclic tetrameric silazane [Me(2)SiNH](4) with H(3)Al.NMe(3) did not give simple aluminum amides, but complicated mixtures were obtained from which the interesting polycyclic species Al(5)C(22)H(73)N(10)Si(8).C(6)H(6) (5) and Al(6)C(22)H(76)N(10)Si(8).1/4 C(6)H(14) (6) could be isolated in low yields. A key step in the formation of 5 and 6 is a low-temperature dehydrosilylation reaction which leads to cleavage of the silazane ring. Compounds 1, 3, and 4 were characterized spectroscopically ((1)H, (13)C, (27)Al NMR and FTIR) and by single crystal X-ray diffraction, whereas 5 and 6 were characterized by X-ray diffraction only. Thermolysis experiments involving 1 and 3 indicate that the onset of Al-N bond formation via dehydrosilylation is accompanied by loss of trimethylamine and formation of larger aggregates, which are stable to further silane elimination to at least 620 degrees C.