Fig. 1. Optical microscopy images of the crystal of (a) Cu₄@oCBT, (b) Cu₄@mCBT and (c) Cu₄@ICBT (insets show the schematic representations of the morphology). Single crystal structure of (d) Cu₄@oCBT, (e) Cu₄@mCBT and (f) Cu₄@ICBT having a nearly square planar Cu₄ core and a butterfly type Cu₄S₄ staple, protected by four carboranes in a twisted fashion. (g–i) The comparative structural analogy of the Cu₄S₄ staple reveals the flattening of the Cu₄S₄ staple for the Cu₄@ICBT NC in comparison to other clusters due to three iodine insertions in the structure. Inset shows the wing flapping of the respective butterfly. Color code: orange = copper, yellow = sulfur, pink = boron, violet = iodine, gray = carbon and white = hydrogen.