New organic-inorganic bromide (P(C₄H₉)₄)₂[ZnBr₄]: crystal structure, vibrational properties, and electrical...

There has been a lot of interest in the development of a novel hybrid material based on zinc with fascinating structural and physical properties. In this paper, a novel organic-inorganic hybrid (P(C₄H₉)₄)₂[ZnBr₄] crystal was synthesized via the slow evaporation method at room temperature and characterized by single-crystal X-ray diffraction, supported by density functional theory, vibrational spectroscopy and electrical analysis. At room temperature, it crystallizes in the monoclinic system (P2₁/c space group) with cell parameters a = 15.3260(11) Å, b = 17.6692(13) Å, c = 16.9898(11) Å, β = 114.715(2)°, V = 4179.4(5) ų and Z = 4. Its structure comprises two crystallographically independent organic (P(C₄H₉)₄)⁺ cations and one type of isolated [ZnBr₄]^2- anion. Each tetrahedral [ZnBr₄]^2- anion is surrounded by three tetrabutylphosphonium cations, forming multiple C-H⋯Br contacts that reinforce the structural framework. The density functional theory (DFT)-calculated Raman and IR spectra are in excellent agreement with the experimental data, allowing unambiguous assignment of vibrational modes, including metal-halogen stretches and the dynamics of the organic cations. Electrical impedance spectroscopy demonstrates temperature- and frequency-dependent conductivity with a negative temperature coefficient of resistance, indicating thermistor-like behavior. AC conductivity follows Jonscher's universal power law and is well described by the correlated barrier hopping model. These multifaceted findings establish (P(C₄H₉)₄)₂[ZnBr₄] as a multifunctional hybrid material suitable for integration into next-generation electronic and optoelectronic devices.