It　has　been　a　long-sought　goal　in　cluster　science　to　discover　stable　atomic　clusters　as　building　blocks　for　cluster-assembled　nanomaterials,　as　exemplified　by　the　fullerenes　and　their　subsequent　bulk　syntheses.([1,2])　Clusters　have　also　been　considered　as　models　to　understand　bulk　properties,　providing　a　bridge　between　molecular　and　solid-state　chemistry.([3])　Because　of　its　electron　deficiency,　boron　is　an　interesting　element　with　unusual　polymorphism.　While　bulk　boron　is　known　to　be　dominated　by　the　three-dimensional　(3D)　B-12　icosahedral　motifs,([4])　new　forms　of　elemental　boron　are　continuing　to　be　discovered.([5])　In　contrast　to　the　3D　cages　commonly　found　in　bulk　boron,　in　the　gas　phase　two-dimensional　(2D)　boron　clusters　are　prevalent.([6-8])　The　unusual　planar　boron　clusters　have　been　suggested　as　potential　new　bulking　blocks　or　ligands　in　chemistry.([6a])　Herein　we　report　a　joint　experimental　and　theoretical　study　on　the　[Ta2B6](-)　and　[Ta2B6]　clusters.　We　found　that　the　most　stable　structures　of　both　the　neutral　and　anion　are　D-6h　bipyramidal,　similar　to　the　recently　discovered　MB6M　structural　motif　in　the　Ti7Rh4Ir2B8　solid　compound.([9])