How does CO+ ion not follow normal trend of molecular orbital theory. Name the effect exhibited by the ion.

1. The CO⁺ does not follow the trend because, bond order of CO is 3 and the  molecular orbital arrangement is as follows:

  $\sigma 1s^2, {\sigma }^{*}1s^2,\sigma 2s^2, {\sigma }^{*}2s^2,\left\{\begin{array}{l}\pi 2{p_y}^2\\ \pi 2{p_z}^2\end{array}\right., \sigma 2{p_x}^2$
But when an electron is removed and CO⁺ is formed, bond order becomes 2.5. The contrasting situation occurs when bond length is reduced from 1.28 A to 1.15 A in CO⁺ from CO.

According to trend, with decrease in bond order, bond length should increase, but it is actually decreased.

There is no name for this effect.