FULL PAPER Synthesis, X‐ray characterization and density functional theory studies of N 6 ‐benzyl‐N 6 ‐methyladenine–M(II) complexes (M = Zn, Cd): The prominent role of π–π,C–H···π and anion–π interactions Roser Pons 1 | Cristina Ibáñez 1 | Ana B. Buades 1 | Antonio Franconetti 1 | Angel Garcia‐Raso 1 | Juan J. Fiol 1 | Angel Terrón 1 | Elies Molins 2 | Antonio Frontera 1 1 Departament de Química, Universitat de les Illes Balears, Crta de Valldemossa km 7.5, 07122 Palma de Mallorca (Baleares), Spain 2 Institut de Ciència de Materials de Barcelona (ICMAB‐CSIC), Campus Universitat Autònoma de Barcelona, 08193 Cerdanyola, Spain Correspondence Angel Garcia‐Raso and Antonio Frontera, Departament de Química, Universitat de les Illes Balears, Crta de Valldemossa km 7.5, 07122 Palma de Mallorca (Baleares), Spain. Email: angel.garcia‐raso@uib.es; toni. frontera@uib.es We report the synthesis and X‐ray characterization of the N 6 ‐benzyl‐N 6 ‐ methyladenine ligand (L) and three metal complexes, namely [Zn(HL) Cl 3 ]·H 2 O(1), [Cd(HL) 2 Cl 4 ](2) and [H 2 L] 2 [Cd 3 (μ‐L) 2 (μ‐Cl) 4 Cl 6 ]·3H 2 O(3). Com- plex 1 consists of the 7H‐adenine tautomer protonated at N3 and coordinated to a tetrahedral Zn(II) metal centre through N9. The octahedral Cd(II) in complex 2 is N 9 ‐coordinated to two N 6 ‐benzyl‐N 6 ‐methyladeninium ligands (7H‐tautomer protonated at N3) that occupy apical positions and four chlorido ligands form the basal plane. Compound 3 corresponds to a trinuclear Cd(II) complex, where the central Cd atom is six‐coordinated to two bridging μ‐L and four bridging μ‐Cl ligands. The other two Cd atoms are six‐coordinated to three terminal chlorido ligands, to two bridging μ‐Cl ligands and to the bridging μ‐L through N3. Essentially, the coordination patterns, degree of pro- tonation and tautomeric forms of the nucleobase dominate the solid‐state architectures of 1–3. Additionally, the hydrogen‐bonding interactions produced by the endocyclic N atoms and NH groups stabilize high‐dimensional‐order supramolecular assemblies. Moreover, energetically strong anion–π and lone pair (lp)–π interactions are important in constructing the final solid‐state archi- tectures in 1–3. We have studied the non‐covalent interactions energetically using density functional theory calculations and rationalized the interactions using molecular electrostatic potential surfaces and Bader's theory of atoms in molecules. We have particularly analysed cooperative lp–π and anion–π interactions in 1 and π + –π + interactions in 3. KEYWORDS Cd(II)–cytokinin complex, cytokinin, DFT calculations, noncovalent interactions, Zn(II)–cytokinin complex Received: 31 January 2019 Revised: 17 February 2019 Accepted: 20 February 2019 DOI: 10.1002/aoc.4906 Appl Organometal Chem. 2019;e4906. https://doi.org/10.1002/aoc.4906 © 2019 John Wiley & Sons, Ltd. wileyonlinelibrary.com/journal/aoc 2 of 11