title: Density functional theoretical investigation on structure, optical response and hydrogen adsorption properties of B9/metal-B9 clusters.
abstract: DFT calculations have been carried out to shed light on the electronic structure, optical properties and hydrogen adsorption capability of neutral MB9 (where M = Li3, Na3, K3, Al, Ga, In, Rh and Co) clusters. Electronic structural studies on the parent B9(3-) clusters reveal that a less aromatic hypervalent B-centred B8 ring geometry is energetically more favoured. However, GM(3+) (Al, Ga and In) in GM@B9 prefers a highly aromatic metal-centred 9-membered molecular wheel structure. In addition, the larger size of indium breaks the D9h symmetry of the molecular wheel by coming slightly out of the ring plane unlike Al@B9 and Ga@B9. B9(n-) (n = 1-3) is also neutralized with 'n' number of Li, Na and K which revealed that AM2B9 and AM2B9(-) result in pyramidal geometries while AM3B9 results in an irregular shape by retaining the B9 framework similar to the most stable conformer of B9(3-). Metal@B9 molecular wheels show optical absorption in a broad range of the spectrum (from UV to NIR: 260-1000 nm), which is attributed to the metal's ability to perturb the ring centred excited state. Ga@B9 and Co@B9 bind with hydrogen molecules in a dissociative manner, forming two covalent bonds with peripheral B atoms of the B9 ring.
authors.affiliation: New Chemistry Unit, Jawaharlal Nehru Center for Advanced Scientific Research, Jakkur P. O., Bangalore 560064, India.
authors.forename: Swastika
authors.initials: S
authors.lastname: Banerjee
authors.forename: Ganga
authors.initials: G
authors.lastname: Periyasamy
authors.forename: Swapan K
authors.initials: SK
authors.lastname: Pati