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Among the series of stable closo -borate dianions, [B n H n ] 2− , the X-ray crystallographic structure of [B 7 H 7 ] 2− was determined only in 2011. To explore its chemistry and stability, we have isolated and structurally characterized two new transition metal complexes of the heptaborane, [(Cp 2 M) 2 B 9 H 11 ] (Cp = η 5 -C 5 H 5 ; M = Zr or Hf). The structures of [(Cp 2 M) 2 B 9 H 11 ] contain a pentagonal bipyramidal B 7 core, coordinated by two {Cp 2 M} and two {BH 2 } units equatorially. Structural and spectroscopic characterizations and DFT calculations show that [(Cp 2 M) 2 B 9 H 11 ] complexes are substantially more stable than the parent dianion, in either [B 7 H 7 ] 2− or ( n Bu 4 N) 2 [B 7 H 7 ]. Our theoretical study and chemical bonding analyses reveal that the surprising stability of the two new heptaborane metal complexes is due to multi-center covalent bonds related to the two exo -{Cp 2 M} units, as well as electrostatic interactions between the {Cp 2 M} units and the B 7 core. The facile syntheses of the heptaborane metal-complexes will allow further exploration of their chemistry.