Density functional theory (DFT) calculations were used to probe the reaction of the diruthenaborane nido-[1,2-(Cp*RuH)2B3H7] (Cp* = g5-C5Me5), (1) with MeC: CMe to form the major product nido-[1,2-(Cp*Ru)2 (μ-H)(μ-BH2)-4,5-Me2-4,5-C2B2H4] (2) along with minor product nido-(Cp*Ru)2-4,5-Me2-4,5-C2B2H6 (3). The structural features of the other related diruthenacarboranes, nido-(Cp*Ru)2-4,5-Me2-4,5-C2B2H6 (4) and closo-1,2-(Cp* RuH)2-4,5-Me2-4,5-C2B3H3 (5), were also studied. Since metallaheteroboranes with p-block group-14 elements are rare, we extend our DFT studies to explore the reaction of 1 with heavier group-14 alkyne analogs, RE ≡ ER (E = Si, Ge, and Sn; R = alkyl or aryl groups). The geometrical and electronic structures of the products nido-[1,2-(Cp*Ru)2(μ-H) (μ-BH2)-4,5-Me2-4,5-E2B2H4] (E = Si (6), Ge (7), Sn (8)) are described and compared with the ruthenacarborane analog, nido-[1,2-(Cp*Ru)2(l-H)(l-BH2)-4,5-Me2-4,5-C2B2H4] species, 2. The computed energetics and the geometries support the feasibility of the reaction and the stability of the products. NBO analysis was performed to delve further into the nature of the bonding in this kind of clusters.

Sundargopal Ghosh

Department Of Chemistry

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Theoretical Chemistry Accounts

Density functional theory (DFT) has been used to probe the bonding and electronic properties of dimolybdaborane [(Cp*Mo)2B 5H9], 1 (Cp* = η5-C 5Me5), and several other heterodimolybdaborane clusters, such as [(Cp*Mo)2B5(μ3-OEt)H 7] (2), [(Cp*Mo)2B5(μ3-OEt) (n-BuO)H6] (3), [(η5-C5H5W) 2B4H4S2] (4), and [(Cp*Mo)2B4H4E2] (5-7, where, for 5, E = S, for 6, E = Se, and for 7, E = Te). The DFT results were also used to address some key points such as (i) the metal-metal bond length, (ii) the location and number of bridging and terminal hydrogen atoms, (iii) the molecular orbital analysis, and (iv) the assignment of 11B and 1H NMR chemical shifts. These studies further provide meticulous insight into similarities and differences between various dimetallaborane clusters 1-7. In addition, the crystal structures of 5 and 7 are reported, which come on top of the already existing literature of dimetallaboranes and support the theoretical findings. © 2012 American Chemical Society.

Inorganic Chemistry

Theoretical and experimental investigations on hypoelectronic heterodimetallaboranes of group 6 transition metals

European Journal of Inorganic Chemistry

Spotlights on our sister journals: Eur. J. Inorg. Chem. 5/2016

Mild thermolysis of tantalaborane [(Cp*Ta) 2B 5H 11], 1 (Cp* = η 5-C 5Me 5) in presence of halogen sources affords the open cage clusters [(Cp*TaX) 2B 5H 11], 2-4 (2: X = Cl; 3: X = Br; and 4: X = I) in good yields. In contrast, the tetraborohydride cluster, [(Cp*Ta) 2B 4H 9(μ-BH 4)], 5, under the same reaction conditions forms the B-H substituted cluster [(Cp*Ta) 2B 4H 8I(μ-BH 4)], 6. All the new metallaboranes have been characterized by mass spectrometry, 1H, 11B, 13C 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 11B chemical shifts accurately reflect the experimentally measured shifts. Clusters 2-4 can be viewed as 7-sep 7-vertex oblatoarachno M 2B 5 clusters which can be generated from a 7-sep 9-vertex oblatocloso M 2B 7 cluster by removal of two equatorial boron atoms. Cluster 6 can be considered as an electron-deficient 6-sep 6-vertex oblatoarachno M 2B 4 cluster derived from an 8-vertex oblatocloso hexagonal bipyramidal cluster, in which BH 4 - anion is weakly bonded in a bidentate mode. © 2012 American Chemical Society.

Synthesis and characterization of hypoelectronic tantalaboranes: Comparison of the geometric and electronic structures of [(Cp*TaX) 2B 5H 11] (X = Cl, Br, and I)

Journal	Theoretical Chemistry Accounts
ISSN	1432881X
Open Access	No