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The trinuclear [Zn3(PMT)2(Cl4)(N3)2] complex of the N-pincer ligand, 2,4-bis(3,5-dimethyl-1H-pyrazol-1-yl)-6-methoxy-1,3,5-triazine (PMT), was obtained by self-assembly of the polydentate ligand (PMT) with ZnCl2 in the presence of azide ion as an auxiliary bridging ligand. The X-ray structure analysis revealed a monoclinic crystal system and centrosymmetric space group C2/c. There are two crystallographically independent Zn(II) sites where the Zn1 and Zn2 are tetra- and penta-coordinated with ZnN2Cl2 and ZnN4Cl coordination environments, respectively. The distortion τ4 and τ5 parameters for the Zn1 and Zn2 sites are 0.93 and 0.52, respectively. Hence, the Zn(1)N2Cl2 has a distorted tetrahedral configuration, while the Zn(2)N4Cl coordination sphere is intermediate between the square pyramidal and trigonal bipyramidal configurations. In this complex, the PMT is a tridentate N-chelate, while the chloride and azide anions are terminal and μ(1,1) bridged ligands, respectively. The %H…H, N…H, Cl…H, and C…H are 40.8, 17.2, 16.0, and 10.1%, respectively, based on Hirshfeld analysis. The charges at the Zn1 (+0.996 e) and Zn2 (+1.067 e) sites are calculated to be less than the official charge of the isolated Zn(II) ion. The μ(1,1) bridged azide has two asymmetric N–N bonds with clear covalent characters. In contrast, the Zn–N and Zn–Cl bonds have predominant closed-shell characters.

Two penta-coordinated [Co(MorphBPT)Cl2]; 1 and [Co(PipBPT)Cl2]; 2 complexes with the bis-pyrazolyl-s-triazine pincer ligands MorphBPT and PipBPT were synthesized and characterized. Both MorphBPT and PipBPT act as NNN-tridentate pincer chelates coordinating the Co(II) center with one short Co-N(s-triazine) and two longer Co-N(pyrazole) bonds. The coordination number of Co(II) is five in both complexes, and the geometry around Co(II) ion is a distorted square pyramidal in 1, while 2 shows more distortion. In both complexes, the packing is dominated by Cl…H, C-H…π, and Cl…C (anion-π stacking) interactions in addition to O…H interactions, which are found only in 1. The UV-Vis spectral band at 564 nm was assigned to metal–ligand charge transfer transitions based on TD-DFT calculations. Complexes 1 and 2 showed higher antimicrobial activity compared to the respective free ligand MorphBPT and PipBPT, which were not active. MIC values indicated that 2 had better activity against S. aureus, B. subtilis, and P. vulgaris than 1. DPPH free radical scavenging assay revealed that all the studied compounds showed weak to moderate antioxidant activity where the nature of the substituent at the s-triazine core has a significant impact on the antioxidant activity.

A new dinuclear Cd(II)-azido complex of 2,4-bis(3,5-dimethyl-1H-pyrazol-1-yl)-6-methoxy-1,3,5-triazine (PMT) pincer ligand is synthesized. Its single crystal X-ray structure reveals the dinuclear [Cd(PMT)(Cl)(N3)]2 formula. The triclinic crystal parameters are a = 9.323(4) Å, b = 10.936(5) Å, c = 11.312(6) Å, α = 112.637(10)°, β = 104.547(11)° and γ = 105.133(10)° while V = 944.1(8) Å3. Due to symmetry considerations, the asymmetric unit comprises a half [Cd(PMT)(Cl)(N3)]2 formula. The Cd(II) is hexa-coordinated with one tridentate PMT ligand in a pincer fashion mode in addition to one terminal chloride and two azide ions bridging the two Cd(II) centers in double μ(1,1) bridging mode. Unusually, the Cd-N(s-triazine) bond is not the shortest among the Cd-N interactions with the PMT pincer ligand. The supramolecular structure of the dinuclear [Cd(PMT)(Cl)(N3)]2 formula is controlled by a significant amount of Cl…H (16.4%), N…H (25.3%), H…C (9.8%) and H…H (37.2%) interactions based on Hirshfeld surface analysis. Careful inspection of the shape index map reveals the presence of some weak π-π stacking interactions between the s-triazine and pyrazolyl moieties. The percentage of C…C contacts is 1.9% where the C2…C8 (3.462 Å) is the shortest while the centroid–centroid distance is 3.686 Å. Natural charge analysis describes the charge transferences from the ligand groups to the Cd(II), while and atoms in molecules (AIM) give an indication on the properties of the Cd-N and Cd-Cl bonds.

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