Cooling the Mössbauer sample to 80 K resulted in broadening of the signal attributed to the Fe II site, while the signal associated with CpFe(CO)2 remains almost unchanged. In threecoordinate β-diketiminatoiron(II) complexes, such broadening upon decreasing temperature is indicative of slow magnetic relaxation caused by the presence of orbital near-degeneracy, and increased spin-orbit coupling. On the other hand, the Mössbauer spectrum of 1b at 80 K displayed no evidence of broadening of the doublet attributed to the Fe II site. Modelling the 80 K Mössbauer spectrum of 1b as a staggered conformation afforded two equal-intensity doublets with fit parameters comparable to those of 1a, with δ (|DEQ|) of 0.65 mm s -1 (|DEQ| = 0.79 mm s -1 ) and 0.05 mms -1 (|DEQ| = 1.70 mm s -1 ). These are assigned as L b Fe II and CpFe 0 (CO)2, as in 1a. We gained deeper insight into the magnetic properties of 1a and 1b using SQUID magnetometry. The variable temperature magnetic susceptibility data of 1a were collected under a d.c. magnetic field of 1000 Oe, and they reveal non-Curie law behaviour, consistent with a magnetically anisotropic ground state (Figure ). The χMT value of 4.05 cm 3 K/mol at 300 K supports an S = 2 ground state with a giso value of 2.32, consistent with the high-spin of -13 cm -1 and 0 cm -1 , respectively. A summary of the spectroscopic and magnetic data for both complexes can be found in Table . Density functional theory (DFT) calculations were performed using ORCA 4.0 software.