The design of new molecular based magnets requires a deep understanding of all relevant processes responsible for the bulk magnetic properties. It is common practice to use suitable bridging ligands for optimization of the overlap between magnetic properties and thus the exchange interaction. However, the choice of the bridging ligands may be dictated by other consideration than the optimization of the magnetic properties. A good alternative way is to use a combination of the exchange interaction and a through space dipolar coupling. In this contribution we present a model that takes into account the dipolar interaction between quantum spin chains and explains the occurrence of three-dimensional (3D) ordering in magnetic chain compounds, where superexchange interaction can be neglected because of large interchain spacing. The dipolar interaction takes place not between individual spins but between correlated spin blocks arising from the divergence of the 1D correlation length at low temperature. Using a modified mean-field approach it is shown that the strength of this interaction is large enough to induce 3D magnetic ordering.FigureSchematic structure of [Mn^III(TPP)][TCNE]FigureFerrimagnetic chain as a set of spatially distributed superspinsThe model is applied to the Mn-porphyrin-based magnets exhibiting ferrimagnetic chains well separated in space (up to 30 Å apart). In the framework of the developed approach, critical temperatures reasonably close to the experimental ones are obtained. It is shown that the rate of increase of the correlation length at low temperature is the essential parameter in order to reach the observed transition temperatures. An exponential divergence of the 1D correlation length is required, which implies the existence of single-ion anisotropy, whereas the power-law divergence for 1D Heisenberg coupled spins yields transition temperatures one order of magnitude smaller than observed. Different ground-state spin alignments are analyzed. Depending on the symmetry of the single-ion magnetic anisotropy, different ground-state configurations can be stabilized, parallel or canted, but in all cases, the system splits into domains with ferromagnetic spin alignment within each domain.FigureStripes spin alignmentFigureCanted stripes spin alignmentIn this respect, a combination of the exchange interaction and a through space dipolar coupling for the design of molecular ferromagnets may appear very promising in the future.