Phase transitions between crystalline HOIP polymorphs upon application of external stimuli such as temperature or pressure are relatively common. Such transitions are commonly associated with, amongst other factors, displacement of the organic A site cation, and a large anisotropic thermal expansion. For example, [TPrA][Mn(dca)3] (TPrA = tetrapropylammonium, [(CH3CH2CH2)4N] + ), displays a first-order structural phase transition at 57 °C from a non-centrosymmetric structure (space group P4̅ 21c), to a high temperature polymorph with the centrosymmetric space group I4/mcm. Despite the dominance of the solid crystalline state in the family, several HOIPs have recently been demonstrated the ability to melt into liquid phases. This is unusual given the thermal decomposition observed prior to melting in most organic-inorganic networks. Dicyanamide-based hybrid organic-inorganic ABX3 structures containing both tributylmethylammonium and tetrapropylammonium as the 'A-site' cation have however been shown to undergo melting upon heating. The [TPrA][M(dca)3] (M = Mn, Fe, Co) series melt at temperatures ~ 250 °C, via M-N coordination bond breaking and the formation of under-coordinated M centres. Interestingly, cooling of these high temperature liquids back to room temperature results in glass formation. Importantly, and differentiating them from glasses formed by melt-quenching MOFs, they exhibit interesting electronic/phononic properties with potential applications in e.g. thermoelectrics. In this work, we look to lower melting temperatures through careful modification of A-site and B-site species. Specifically, we investigate the structure-property correlation between hybrid organic-inorganic ABX3 structures with different chemical compositions and their melting and glass transition temperatures (Tm and Tg). We modify the size of the organic A cation in [TAlA][M(dca)3] (TAlA = tetralkylammonium linker, M = Mn, Fe, Co) structures through the introduction of successively larger tetrabutylammonium (TBuA = tetrabutylammonium, (CH3CH2CH2CH2)4N + ) and tetrapentylammonium (TPnA = tetrapentylammonium, (CH3CH2CH2CH2CH2)4N + ) species (Fig. ). This results in a series of nine ABX3 structures, of which four are previously unreported. Structural characterisation techniques allow Tolerance Factors to be calculated for each, which are then linked to thermal analysis in order to rationalize the reduction in Tm upon increasing A cation size. 29