Crystal structures and Hirshfeld surface analysis of trans-bis-(thio-cyanato-κN)bis-{2,4,6-trimethyl-N-[(pyridin-2-yl)methyl-idene]aniline-κ2 N,N'}manganese(II) and trans-bis-(thio-cyanato-κN)bis-{2,4,6-trimethyl-N-[(pyridin-2-yl)methyl-idene]aniline-κ 2 N,N'}nickel(II)).

Two new mononuclear metal complexes involving the bidentate Schiff base ligand 2,4,6-trimethyl-N-[(pyridin-2-yl)methyl-idene]aniline (C15H16N2 or PM-TMA), [Mn(NCS)2(PM-TMA)2] (I) and [Ni(NCS)2(PM-TMA)2] (II), were synthesized and their structures determined by single-crystal X-ray diffraction. Although the title compounds crystallize in different crystal systems [triclinic for (I) and monoclinic for (II)], both asymmetric units consist of one-half of the complex mol-ecule, i.e. one metal(II) cation, one PM-TMA ligand, and one N-bound thio-cyanate anion. In both complexes, the metal(II) cation is located on a centre of inversion and adopts a distorted octa-hedral coordination environment defined by four N atoms from two symmetry-related PM-TMA ligands in the equatorial plane and two N atoms from two symmetry-related NCS- anions in a trans axial arrangement. The tri-methyl-benzene and pyridine rings of the PM-TMA ligand are oriented at dihedral angles of 74.18 (7) and 77.70 (12)° for (I) and (II), respectively. The subtle change in size of the central metal cations leads to a different crystal packing arrangement for (I) and (II) that is dominated by weak C-H⋯S, C-H⋯π, and π-π inter-actions. Hirshfeld surface analysis and two-dimensional fingerprint plots were used to qu-antify these inter-molecular contacts, and indicate that the most significant contacts in packing are H⋯H [48.1% for (I) and 54.9% for (II)], followed by H⋯C/C⋯H [24.1% for (I) and 15.7% for (II)], and H⋯S/S⋯H [21.1% for (I) and 21.1% for (II)].