X-ray structural characterization of some sterically bulky N-donor and N-alkyl Grignard reagents

[MgBr2(thf)3] (1) and [FisoMg(thf)Cl]2 (2), (Fiso− = [ArNC(H)NAr]−, View the MathML sourceAr=C6H3Pr2i-2,6), [2-PyC(SiMe3)2Mg(thf)Cl]2 (3), [2-PyC(SiMe3)2Mg(thf)Br]2 (4), and [(2-PyC(SiMe3)2Mg(thf))2(OEt)Cl] · Et2O (5). (2-Py(SiMe3)2CH = 2-{bis-(trimethylsilyl)methyl}2-pyridine) were isolated as by-products from reactions involving organometallic species and magnesium or diethylmagnesium. All compounds were characterized by single crystal X-ray crystallography. Compounds (1) and (5) have trigonal bipyramidal magnesium centres, while compounds (2)–(4) have square pyramidal structures. Compound (1) is monomeric, while compounds (2)–(5) are dinuclear with magnesium centres bridged by two halides for (2)–(4), and a chloride and an ethoxy ligand in (5).