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. 2020 Jun 9;7(Pt 4):581–629. doi: 10.1107/S2052252520005928

Table 4. Ion configurations with anomalous bond-length distribution when bonded to O2− .

Mechanisms are listed in decreasing order of importance: BTE denotes bond-topological effects, π pi-bond formation, JTEs strong Jahn–Teller effect, JTEw weak Jahn–Teller effect, PJTE pseudo Jahn–Teller effect, CSE crystal-structure effects.

Ion configuration Electronic configuration Anomalous shape? Sample size (No. of coordination polyhedra) Bond-length range (Å) Δtopol > Δcryst? Mechanism(s)
[6]Sc3+ d 0 Yes 75 0.236 Yes BTE, PJTE
[4]Ti4+ d 0   4 0.159   PJTE, BTE
[5]Ti4+ d 0 Yes 17 0.405   PJTE, BTE
[6]Ti4+ d 0 Yes 293 0.826   PJTE, BTE
[7]Ti4+ d 0 Yes 1 0.55 No data PJTE
[6]V3+ d 2 Yes 67 0.399 Yes BTE, JTEw
[5]V4+ d 1 Yes 95 0.577 Yes π, PJTE/BTE/CSE
[6]V4+ d 1 Yes 128 1.030 Yes π, PJTE/BTE
[4]V5+ d 0 Yes 355 0.391 Yes BTE, PJTE
[5]V5+ d 0 Yes 65 0.801 Yes π, PJTE, BTE
[6]V5+ d 0 Yes 293 0.993 Yes π, BTE/PJTE
[5]Cr2+ d 4   2 0.432   PJTE, BTE
[6]Cr2+ d 4 Yes 9 0.696 Yes JTEs/BTE
[6]Cr3+ d 3 Yes 104 0.19 Similar BTE, CSE
[4]Cr6+ d 0 Yes 169 0.357 Yes BTE, PJTE, π
[6]Mn3+ d 4 Yes 82 0.755   JTEs, BTE
[4]Fe3+ d 5 Yes 65 0.201 Yes BTE
[5]Co2+ d 7   16 0.628   PJTE
[6]Co2+ d 7   243 0.614 Yes BTE, JTEs
[5]Cu2+ d 9   218 0.865   PJTE, BTE
[6]Cu2+ d 9 Yes 365 0.893   JTEs, BTE
[6]Zn2+ d 10   193 0.868 Similar BTE/PJTE
[6]Y3+ d 0 Yes 25 0.226 Similar PJTE/BTE
[7]Y3+ d 0 Yes 35 0.499   PJTE
[8]Y3+ d 0 Yes 99 0.507   PJTE/BTE
[9]Y3+ d 0   15 0.585   PJTE, BTE
[10]Y3+ d 0   1 0.604 Yes BTE/PJTE
[6]Zr4+ d 0 Yes 73 0.218   PJTE, BTE
[4]Nb5+ d 0   2 0.184 No data PJTE/BTE
[5]Nb5+ d 0 Yes 4 0.164   PJTE/BTE
[6]Nb5+ d 0 Yes 240 0.742   PJTE, BTE
[7]Nb5+ d 0   3 0.668   PJTE, BTE
[6]Mo4+ d 2 Yes 9 0.264 Yes BTE
[5]Mo5+ d 1 Yes 2 0.328 No data π
[6]Mo5+ d 1 Yes 74 0.806 Yes π, BTE, JTEw
[4]Mo6+ d 0 Possibly 434 0.268 Yes BTE, PJTE
[5]Mo6+ d 0   15 0.620 Yes π, BTE/PJTE
[6]Mo6+ d 0 Yes 506 1.005   PJTE, BTE
[6]Ru5+ d 3 Yes 23 0.305   CSE/BTE
[6]Cd2+ d 10   135 0.591 Yes BTE, PJTE
[6]Hf4+ d 0 Possibly 11 0.322   PJTE, BTE
[6]Ta5+ d 0 Yes 138 0.585   PJTE, BTE
[7]Ta5+ d 0 Possibly 14 0.619   PJTE, BTE
[5]W6+ d 0   12 0.467   PJTE, BTE
[6]W6+ d 0 Yes 363 0.919   PJTE, BTE
[4]Re7+ d 0 Yes 41 0.150 Yes BTE, PJTE
[5]Re7+ d 0 Possibly 8 0.275   PJTE
[6]Re7+ d 0   10 0.195 Yes PJTE, BTE
[6]Os6+ d 2 Possibly 1 0.266 No data BTE
[5]Os8+ d 0 Possibly 3 0.569   PJTE, BTE
[6]Os8+ d 0 Yes 4 0.442   PJTE, BTE
[6]Hg2+ d 10 Yes 25 0.912 Similar BTE/PJTE