Vacancy-ordered double perovskites A₂BX₆ are attracting attention due to the isolated octahedra making them an ideal playground for studying perovskite structure-property relationships. MA₂TeCl₆ single crystals have been successfully grown from solution. X-ray structure experiments as a function of temperature have demonstrated two structural phase transitions: from cubic Fmm (high temperature, phase I) to trigonal Pm1 (intermediate temperature, phase II) at 460 K and then to trigonal P1c (low temperature, phase III) at 200 K. Intriguingly, we observe a negative thermal expansion for the c-axis in phase II believed to caused by dynamic tilting of the C–N bond in the MA⁺ ion. We have modified and extended the calculation of the Brown radii ratio in the perovskites to include hybrid A₂BX₆ compounds by selecting the shortest A–X distance for the ratio equation. We find that for ratios between 0.89 and 1.17, typically the Fmm cubic structure is observed, while for ratios above 1.17, mostly distorted structures are found.