Chung-Cheng Chang

Chemical reactivities of [Me2Al(µ-NPri2)2MgMe]4 and [Me2Al(µ-NEt2)2MgMe]2: crystal structures of [Me2Al(µ-NPri2)2Mg(µ-I)]2, [Me2Al(µ-OBut)2Mg(µ-OBut)]2, Me2Al(µ-NPri2)(µ-OEt)Mg(µ-NPri2)(µ-OEt)AlMe2 and Me2Al(µ-OBut)2Mg(µ-OBut2)2AlMe2

The nucleophilic attack of alcohols, amines and iodine on the magnesium atoms of [Me2Al(µ-NPri2)2MgMe]4A and [Me2Al(µ-NEt2)2MgMe]2B has been investigated. Compound A undergoes metathesis with amines (Et2NH and Pri2NH) and iodine to give [Me2Al(µ-NPri2)2Mg(µ-NR2)](R = Et 7 or Pri4) and [Me2Al(µ-NPri2)2Mg(µ-I)]25, respectively. Partial degradation of A with MeOH or ethanol gives Me2Al(µ-NPri2)(µ-OMe)Mg(µ-NPri2)(µ-OMe)AlMe21a and [Me2Al(µ-NPri2)(µ-OEt)Mg(µ-NPri2)(µ-OEt)AlMe21b, respectively, whereas partial degradation with ButOH gives Me2Al(µ-OBut)2Mg(µ-OBut)2AlMe22 and [Me2Al(µ-OBut)2Mg(µ-OBut)]23. Compound B undergoes metathesis with ButOH also to give 2 and 3. The intermediate, Me2Al(µ-NR2)2Mg(µ-Me)(µ-OBut)Mg(µ-NR2)2AlMe2I in the reactions of A and B with ButOH is also examined. The molecular structures of compounds 1b, 2, 3 and 5 were determined by X-ray diffraction.

Syntheses and spectroscopic studies of X4Al2(μ-NR2)2 [X = Br, CH3, C2H5; R = C2H5, Ci3H7]. X-ray crytal structures of Br4Al2[μ-N(Et)2]2 and Et4Al2[μ-N(Ci3H7)2]2

The reactions of bis(dialkylamino)magnesium [Mg(NR 2 ) 2 ; R = C 2 H 5 , C i 3 H 7 ] with either diethylaluminum chloride or aluminum bromide yielded the following compounds: Me 4 Al 2 [μ-N(C i 3 H 7 ) 2 ] 2 ( 1 , Et 4 Al 2 [μ-N(Et) 2 ] 2 ( 2 ), Et 4 Al 2 [μ-N(C i 3 H 7 ) 2 ] 2 ( 3 ) and Br 4 Al 2 [μ-N(Et) 2 ] 2 ( 4 ). The products were characterized on the basis of their elemental analyses, mass spectra, IR spectra and 1 H, 13 C and 27 Al nuclear magnetic resonance spectra. The X-ray crystal structures of compounds 3 and 4 were also determined. In addition, 1 H NMR studies of the solvent effect on the dialuminum complexes were explored and a spectroscopic investigation of benzene interaction with these dialuminum complexes was undertaken.

Syntheses and molecular structures of multinuclear aluminium complexes Rn+2AlnL2 (n = 3,4; L = diamine, triamine) containing penta-coordinate aluminium atoms

Abstract Reactions of Al2R′4[N(C2H5)2]2 (R′ = CH3, C2H5) with ethylenediamine or N,N′-dimethylethylenediamine yield air-sensitive trialuminium products [AlR′2]2[RNCH2 CH2NR]2[AlR′] (1a: R′ = CH3, R = H; 1b: R′ = CH3; 2a; R′ = C2H5, R = H; 2b: R′ = C2H5, R = CH3). Reactions of Al2R′4[N(C2H5)2]2 with diethylenetriamine, [(NH2CH2CH2)2NH], yield air-sensitive tetraaluminium products, (AlR′2)2 [(HNCH2CH2)2N]2(AlR′)2 (3: R′ = CH3; 4: R′ = C2H5). The polyaluminium complexes are well characterized. Some structures have been determined by X-ray crystallography. For both 1a and 1b the penta-coordination sphere around the central aluminium conforms to a square-pyramidal configuration and the tetra-coordination for the outer two aluminium atoms is a tetrahedral configuration. Complex 4 has two central aluminium atoms with a penta-coordinate square-pyramidal configuration and the outer aluminium atoms in a tetrahedral configuration.

Synthesis, characterization and crystal structures of isothiocyanate and carbodiimide complexes derived from organomagnesium reagents: insertion into Mg–X (X = C or N) bonds

A series of magnesium–isothiocyanate and –carbodiimide insertion products, Mg(SCPhNBu t ) 2 (thf) 2 1, Mg(SCPhNPh) 2 (thf) 2 2, Mg(Pr i NCRNPr i ) 2 (thf) 2 (R = Ph 3, Et 4 or Pr i 5) and Mg(Bu t NCEtNBu t ) 2 (thf) 2 6 have been prepared by the stoichiometric reaction between MgR 2 (R = Ph, Et or Pr i ) and various isothiocyanates and carbodiimides in tetrahydrofuran (thf) solution. The 1∶1 reaction between bis(diisopropylamido)magnesium and 1,3-diisopropylcarbodiimide gave a dinuclear complex Mg 2 (µ-NPr i 2 ) 2 [(Pr i N) 2 CNPr i 2 ] 2 7 and a mononuclear complex Mg[(Pr i N) 2 CNPr i 2 ] 2 (thf) 8 when the stoichiometry is 1∶2. The mononuclear complexes Mg[SC(NPh)NR 2 ] 2 (thf) 2 (R = Pr i 9 or Et 10) were obtained using phenyl isothiocyanate and bis(diethylamido)- or bis(diisopropylamido)-magnesium in 1∶1 stoichiometric ratio. A plausible mechanism for the formation of 7 and 8 is suggested. Reaction between MgEtBr and PhNCS in diethyl ether gave the dinuclear complex Mg 2 (SCEtNPh) 4 (OEt 2 ) 2 11. All of the complexes were characterized by 1 H, 13 C NMR and IR spectroscopy as well as elemental analysis. The crystal structures of 1, 3, 8, 9 and 11 were determined by single-crystal X-ray diffraction. The reaction of complex 1 with an excess of PhNCO resulted in the cyclotrimerization of phenyl isocyanate to give (PhNCO) 3 ·thf.