title: A Spinning Umbrella: Carbon Monoxide and Dinitrogen Bound MB12-Clusters (M = Co, Rh, Ir).
abstract: Strong binding of carbon monoxide (CO) and dinitrogen (N2) by MB12-(M = Co, Rh, Ir) clusters results in a spinning umbrella-like structure. For OCMB12-and NNMB12-complexes, the bond dissociation energy values range within 50.3-67.7 kcal/mol and 25.9-35.7 kcal/mol, respectively, with the maximum value obtained in Ir followed by that in Co and Rh analogues. COMB12-complex is significantly less stable than the corresponding C-side bonded isomer. The associated dissociation processes for OCMB12-and NNMB12-into CO or N2and MB12-are highly endergonic in nature at 298 K, implying their high thermochemical stability with respect to dissociation. In OCMB12-and NNMB12-complexes, the C-O and N-N bonds are found to be elongated by 0.022-0.035 Å along with a large red-shift in the corresponding stretching frequencies, highlighting the occurrence of bond activation therein toward further reactivity due to complexation. The obtained red-shift is explained by the dominance of L←M π-back-donation (L = CO, OC, NN) over L→M σ-donation. The binding of L enhances the energy barrier for the rotation of the inner B3unit within the outer B9ring by 0.4-1.8 kcal/mol, which can be explained by a reduction in the distance of the longest bond between inner B3and outer B9rings upon complexation. A good correlation is found between the change in rotational barrier relative to that in MB12-and the energy associated with the L→M σ-donation. Born-Oppenheimer molecular dynamics simulations further support that the M-L bonds in the studied systems are kinetically stable enough to retain the original forms during the internal rotation of inner B3unit.
authors.affiliation: Department of Chemistry and Center for Theoretical Studies, Indian Institute of Technology Kharagpur , Kharagpur 721302, India.
authors.forename: Ranajit
authors.initials: R
authors.lastname: Saha
authors.affiliation: Department of Chemistry and Center for Theoretical Studies, Indian Institute of Technology Kharagpur , Kharagpur 721302, India.
authors.forename: Susmita
authors.initials: S
authors.lastname: Kar
authors.affiliation: Departamento de Física Aplicada, Centro de Investigación y de Estudios Avanzados , Unidad Mérida. km 6 Antigua carretera a Progreso, Apartado Postal 73, Cordemex, C.P. 97310, Mérida, Yucatán, México.
authors.forename: Sudip
authors.identifier: http://orcid.org/0000-0003-3172-926X
authors.initials: S
authors.lastname: Pan
authors.affiliation: Unidad Académica de Ciencias Químicas, Área de Ciencias de la Salud, Universidad Autónoma de Zacatecas , Km. 6 carretera Zacatecas-Guadalajara s/n, Ejido La Escondida, C.P. 98160, Zacatecas, Zacatecas, México.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Martínez-Guajardo
authors.affiliation: Departamento de Física Aplicada, Centro de Investigación y de Estudios Avanzados , Unidad Mérida. km 6 Antigua carretera a Progreso, Apartado Postal 73, Cordemex, C.P. 97310, Mérida, Yucatán, México.
authors.forename: Gabriel
authors.identifier: http://orcid.org/0000-0003-1961-8321
authors.initials: G
authors.lastname: Merino
authors.affiliation: Department of Chemistry and Center for Theoretical Studies, Indian Institute of Technology Kharagpur , Kharagpur 721302, India.
authors.forename: Pratim K
authors.identifier: http://orcid.org/0000-0002-5650-7666
authors.initials: PK
authors.lastname: Chattaraj