La3B14-: an inverse triple-decker lanthanide boron cluster.

We report the observation of the first inverse triple-decker complex in a tri-lanthanide-doped boron cluster. Photoelectron spectroscopy of La3B14- reveals well-resolved photodetachment transitions. Quantum chemical studies show that the most stable structure of the La3B14- cluster exhibits a tilted La-B8-La-B8-La inverse triple-decker structure with two conjoined B8 rings sharing a pair of B atoms due to strong inter-layer B-B bonding. The tilted structure enhances both B-B and B-La bonding, resulting in a highly stable inverse triple-decker structure. Theoretical calculations further show that multi-decker conjoined structures are viable as a new class of 1D lanthanide boron nanostructures.