Planarity-Driven Structure–Morphology Correlations in a Co(II) Benzoylacetonate: Comparative Insights across the [M(bzac) ₂ ] Family

Advancing structure-packing-morphology correlations in β-diketonate complexes provides a rigorous framework for how local coordination geometry propagates into supramolecular organization and ultimately governs macroscopic form. Within this context, we report the synthesis, single-crystal and powder X-ray diffraction analysis, targeted CSD mining, BFDH morphology modeling, and complementary quantum calculations of a new cobalt(II) benzoylacetonate, [Co(bzac)₂]. Accurate SC-XRD data at 100 K establish a centrosymmetric trans-CoO₄ chromophore in <i>P</i>2₁/<i>n</i> with a quasi square-planar coordination environment, while PXRD confirms phase purity. In the solid state, [Co(bzac)₂] forms directionally coherent zigzag stacks consistent with its experimentally observed acicular habit. A comparative CSD-survey across [M(bzac)₂] (M= Pb, Sn, Pd̂trans, Pd̂cis, Cu) reveals metal-dependent variations in stereochemistry, chelate planarity, and packing, positioning the cobalt complex at the most planar and structurally coherent limit. BFDH analysis uncovers a monotonic increase in growth anisotropy culminating in [Co(bzac)₂], whose short π-π, metal-π, and C-H···π contacts rationalize its needle-like morphology. FTIR confirms enolization and O,O'-chelation, while UV-vis spectra display ligand-centered π → π* and n → π* transitions. DFT reproduces the experimental symmetry and electronic partitioning, and TD-DFT recovers the absorption envelope. Overall, the integrated SC-XRD ↔ CSD ↔ BFDH ↔ DFT workflow establishes [Co(bzac)₂] as a crystallographic, morphological, and electronic benchmark within the family.