Synthesis and Structural Characterization of Bis(salicylaldiminato)magnesium Complexes of Varying Aggregation and Coordination State

A series of salicylaldiminato ligands [C 6 H 5 N=CHC 6 H 4 OH ( 1 L), 2,6‐ i PrC 6 H 3 N=CHC 6 H 4 OH ( 2 L), and 2,6‐ i PrC 6 H 3 N=CH‐3,5‐ t Bu 2 C 6 H 2 OH ( 3 L)] were treated with Bu 2 Mg in the presence of the appropriate solvent system to yield the crystalline compounds [( 1 L 6 Mg 3 ) · thf] ( 1 ), [( 2 L 2 Mg · thf)] ( 2 ), and [ 3 L 2 Mg] ( 3 ). The products were characterized by 1 H and 13 C NMR spectroscopy and single‐crystal X‐ray diffraction. X‐ray crystallographic analysis revealed that 1 adopts a unique trimeric aggregation state consisting of six‐coordinate magnesium centers. Substitution of the ligand backbone resulted in the formation of the monomeric species 2 and 3 . X‐ray crystallographic analyses revealed 2 as a five‐coordinate, distorted square‐pyramidal magnesium complex and 3 as a four‐coordinate, distorted tetrahedral species. Inspection of the metrical parameters in 1 – 3 indicates a decrease in the Mg–O and Mg–N bond lengths and an increase in the N–Mg–O bite angle with a decreasing coordination number at magnesium.