Synthesis and characterization. The reaction of [NBu4]3[Cr(CN)6] with Mn(ClO4)2.6H2O and 1-Methylimidazole in CH3CN/EtOH (1:1) resulted in a colourless solution that on slow evaporation yielded colourless long rectangular crystals in good yield (~32 %). The purity of 1 was confirmed by elemental analyses and PXRD measurements (Figure ). The TGA analysis of 1 (Figure ) shows that it undergoes a 7.4 % weight loss till 342 K, due to partial loss of bonded solvent molecules (more accurately 1 molecule of bonded ethanol), after which it is stable up to 460 K after which it steadily loses weight till 573 K. The probable reason for the slight deviation in the experimental PXRD pattern is due to the different measurement temperatures (room temperature (298 K) and simulated (120 K)). The asymmetric unit (Figure ) contains a [CrMn1.5] unit where the [Cr(CN)6] 3-unit that is bridged to two Mn centres by the cyanide ligand and adopts an octahedral geometry (continuous shape measures (CShM) program , Table , ESI) with CrC6 surrounding from four bridging and two terminal cyanide ligands. One of the Mn centres, Mn1 with MnN4O2 coordination surrounding in which Mn1 is coordinated to four nitrogen donor atoms from the bridging cyanide ligands and two oxygen donor atoms from ethanol molecules, adopts an octahedral geometry (Table ). This Mn centre lies in a special position and is shared simultaneously by the two Cr centres in the molecular unit (i.e., two asymmetric units). The other Mn centre, Mn2 also adopts octahedral geometry (Table ) with N5O coordination surrounding in which Mn2 is coordinated to three nitrogen donor atoms from 1-methylimidazole, two nitrogen donor atoms from the bridging cyanide ligands and one oxygen donor atom from water molecule. The octahedral distortion parameters for Cr1, Mn1 and Mn2 centres have also been calculated using the Octadist program and have been listed in Mn atoms (Figure , Figure ). At 120 K, the Cr-C bond distances in 1 lie in the range of 2.050(5)-2.079(5) Å, corresponding to Cr(III) state in octahedral geometry. The average Mn2-N bond distance is 2.244 Å which corresponds to a Mn(II) in HS state. The Mn1-N distance from bridging cyanide is 2.212 Å that indicates that Mn1 is also present in the Mn(II) state. From the bond angles, the C-Cr-C(cis) angles are close to 90 ° while the C-Cr-C(trans) bond angles are close to 180 °. The Cr-C-N angles show a slight deviation from linearity [175.5(5)-178.5(5) °] which is expected from literature values. The distance between two diagonally opposite Cr atoms and Mn atoms is 7.689 Å which is the pore size of the tetragonal void in the 1D network (Figure ). A number of attempts were made to obtain the crystal structure of the desolvated and resolvated phases (1.des and 1.res) but no fruitful results could be obtained due to the poor crystal quality.