Carbon monoxide is a strong field ligand that can bind to them.
Many compounds of this group exhibit an effect where non-linear degenerate molecules undergo a distortion that removes their original distortion. The Jahn-Teller effect can be seen in them, and in one theory, the interaction between a magnetic field and paramagnetic compounds of this group can determine if those compounds are high-spin or low-spin. That theory also explains the various colors of compounds of this group. Crystal Field theory explains the spectrochemical series that lists the size of energy differences between this group's orbitals when they are bound in a (*) coordination complex. Carbon monoxide is a strong field ligand that can bind to them. For 10 points, name this group of elements with an incomplete d-orbital, which includes elements like titanium and silver, and is located at the center of the periodic table.
Many compounds of this group exhibit an effect where non-linear degenerate molecules undergo a distortion that removes their original distortion.
transition metals [accept transition element; be nice and accept coordination complexes before mention]