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Synthesis and Characterization of Hypoelectronic Tantalaboranes: Comparison of the Geometric and Electronic Structures of [(Cp*TaX)(2)B5H11] (X = Cl, Br, and I)

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Title Synthesis and Characterization of Hypoelectronic Tantalaboranes: Comparison of the Geometric and Electronic Structures of [(Cp*TaX)(2)B5H11] (X = Cl, Br, and I)
 
Creator GEETHARANI, K
KRISHNAMOORTHY, BS
KAHLAL, S
MOBIN, SM
HALET, JF
GHOSH, S
 
Subject DENSITY-FUNCTIONAL THEORY
TANTALUM HYDRIDE COMPLEXES
EARLY TRANSITION-METALS
HOMOGENEOUS HYDROGENATION CATALYST
REGULAR 2-COMPONENT HAMILTONIANS
NMR CHEMICAL-SHIFTS
CRYSTAL-STRUCTURE
TOPOLOGICAL ANALYSIS
MOLECULAR-GEOMETRY
CORRELATION-ENERGY
 
Description Mild thermolysis of tantalaborane [(Cp*Ta)(2)B5H11], 1 (Cp* = eta(5)-C5Me5) in presence of halogen sources affords the open cage clusters [(Cp*TaX)(2)B5H11], 2-4 (2: X = Cl; 3: X = Br; and 4: X = I) in good yields. In contrast, the tetraborohydride cluster, [(Cp*Ta)(2)B4H9(mu-BH4)], 5, under the same reaction conditions forms the B-H substituted cluster [(Cp*Ta)(2)B4H8I(mu-BH4)], 6. All the new metallaboranes have been characterized by mass spectrometry, H-1, B-11, C-13 NMR spectroscopy, and elemental analysis, and the structural types were established by crystallographic analysis of clusters 3, 4, and 6. Density functional theory (DFT) calculations at the BP86/TZ2P ZORA level reveal geometries in agreement with the structure determinations, large gaps between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) in accord with their stabilities. B3LYP-computed B-11 chemical shifts accurately reflect the experimentally measured shifts. Clusters 2-4 can be viewed as 7-sep 7-vertex oblatoarachno M2B5 clusters which can be generated from a 7-sep 9-vertex oblatocloso M2B7 cluster by removal of two equatorial boron atoms. Cluster 6 can be considered as an electron-deficient 6-sep 6-vertex oblatoarachno M2B4 cluster derived from an 8-vertex oblatocloso hexagonal bipyramidal cluster, in which BH4- anion is weakly bonded in a bidentate mode.
 
Publisher AMER CHEMICAL SOC
 
Date 2014-10-16T13:47:39Z
2014-10-16T13:47:39Z
2012
 
Type Article
 
Identifier INORGANIC CHEMISTRY, 51(19)10176-10184
http://dx.doi.org/10.1021/ic300848f
http://dspace.library.iitb.ac.in/jspui/handle/100/15704
 
Language en