B-10, B-10(-), and B-10(+) are examined at the B3LYP/6-311 +G (d) level to obtain the optimized geometries and vibrational frequencies. All calculations show that quasi-planar B-10 is a closed shell, stable and compact molecule, which suggests that it may possess some special chemical properties. Then the investigations of MB10 and B-10-M-B-10 (M = Li, Na, K) indicate that quasi-planar B-10 can sandwich a metal atom to form half or full sandwich-type metal complexes. The NBO, MOs and vibrational frequencies analyses reveal that stable quasi-planar B-10 may be as a new ligand. These sandwich complexes can also be viewed as quasi-diatomic (or triatomic) systems. (c) 2006 Elsevier B.V. All rights reserved.