As with the limited coordination chemistry of Ni II , Fe II/III , Co II , Mn II/III/IV and Co II described above, the lack of any published homometallic Cr III compounds of H8TBC [8] (and H4TBC [4]) reveals a serious gap in knowledge when it comes to polymetallic clusters of paramagnetic 3d ions. The isolation of 29 clearly shows this (and more 3d-4f chemistry) will be possible, and that it will lead to some exciting new compounds. We also note also that there are zero H8TBC [8]-supported clusters of Cu. All of this chemistry remains to be explored, but is clearly rife for exploitation.