Two dinuclear centrosymmetric coordination compounds with the bis(3,5-di-tert-butylpyrazol-1-yl)acetic acid anion (L– = bdtbpza), namely, violet [Co(bdtbpza)(NO3)]2 (1) and turquoise [Cu(bdtbpza)(NO3)]2 (2), are reported. Around each metal(II) ion, the L– ligand is κ3-N,N,O coordinated, and the M–O bonds are significantly longer than both M–N bonds. The coordination sphere is completed by short nitrato and M–O bonds to a ligand that is already κ3-N,N,O coordinated to the adjacent intra-dinuclear metal center. Therefore, each L– ligand has a total coordination number of four but with different carboxylate modes, namely, κ4-N,N,O,O (1,1) in 1 and κ4-N,N,O,O′ (1,3) in 2 for the C(1)–O–C(2) group. Thus, the coordination spheres are MO2N2O in both cases, though 1 is distorted trigonal bipyramidal, whereas 2 is square pyramidal. Antiferromagnetic (AFM) coupling (17 cm–1) is seen only in 1, though the best fit was obtained with consideration of spin–orbit coupling along with zero-field splitting owing to exchange anisotropy. The new dinuclear nitrato species might be alternatives to previously reported mimics of enzyme active sites.