Structure of two polymorphs of bis-trifluoroacetylacetonato-(N,N,N′N′-tetramethylethylenediamine)magnesium

Abstract

The structures of two polymorphs [Mg(tmeda)(tfac)₂] (tmeda = N,N,N′N′-tetramethylethylenediamine, tfac = trifluoroacetylacetonate anion) are studied by single crystal XRD. The crystallographic data are as follows: for the α-modification, space group P2₁/c, a = 8.0874(4) Å, b = 20.2826(11) Å, c = 12.8759(7) Å, β = 90.6350(1)°, V = 2111.5(19) ų, Z = 4, R = 0.0583; for the β-modification, space group C2/c, a = 8.8698(4) Å, b = 13.3441(8) Å, c = 18.1189(11) Å, β = 92.280(2)°, V = 2142.8(2) ų, Z = 4, R = 0.0537. Both structures are composed of monomeric complex molecules; the magnesium coordination environment is a distorted octahedron; tfac ligands are in the trans-position. The interatomic distances and bond angles are identical in the molecules; the packing motif is the only distinction between the two polymorphs.