= Solution
At fixed $+2$ <oxidation state>, increasing <effective nuclear charge> across the first transition series generally contracts the <ionic radius>. The first expectation is therefore \b[shorter average <metal>–<nitrogen> and <metal>–<sulfur> distances toward copper]. This is a trend in comparable coordination environments, rather than a requirement that every individual contact shorten monotonically. The occupation of <metal>–<coordination ligand> <antibonding orbitals>, donor identity and lattice distortion all affect the observed distances.
The high-spin $d^5$ and $d^6$ ions both have two <electrons> in the strongly sigma-antibonding $e_g$ set, so adding the sixth <electron> to $t_{2g}$ does not itself introduce another sigma-antibonding <electron>. Copper(II), however, has $e_g^3$ occupation and is subject to the <Jahn-Teller effect>. A <tetragonal Jahn-Teller distortion> commonly gives four shorter and two longer contacts, so an elongated copper contact can oppose the overall size trend. Here the <nitrogen> and <sulfur> donors are already chemically inequivalent; the supplied schematic alone does not determine which trans pair becomes longest. One should compare actual M–N and M–S sets separately, rather than infer a unique axis or a numerical distance from the <magnetic moments>. The experimentally determined structures illustrate why the donor geometry and individual contacts matter.<Strengthening the Magnetic Interactions in Pseudobinary First-Row Transition Metal Thiocyanates, M(NCS)2 by Euan N. Bassey and others>[Crystallographic characterization and comparison of the layered structures]{ref}
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