The relevance of boranes and metallaboranes to the structures of p-block element nanoparticles

Fehlner, Thomas P.

doi:10.1016/j.jorganchem.2008.11.018

Cited by 17 publications

(4 citation statements)

References 33 publications

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“…The existence of intermediates will involve many different possible borane chemistries. [18][19][20] Recent experimental 14,16 and theoretical 3,13 studies indicate that the decomposition pathways are not simple one-step reactions ͓Eq. ͑1͔͒ but instead may be a multistep decomposition path.…”

Section: ͑1͒mentioning

confidence: 99%

Theoretical prediction of different decomposition paths forCa(BH4)2and

et al. 2010

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We have studied the decomposition pathways of both Ca-and Mg-borohydride using density-functional theory ͑DFT͒ calculations of the free energy ͑including vibrational contributions͒ in conjunction with a Monte Carlo-based crystal-structure prediction method, the prototype electrostatic ground-state ͑PEGS͒ search method. We find that a recently proposed CaB 2 H 2 intermediate ͓M. D. Riktor, M. H. Sørby, K. Chłopek, M. Fichtner, and B. C. Hauback, J. Mater. Chem. 19, 2754 ͑2009͔͒ is energetically highly unfavorable and hence very unlikely to form. We systematically search for low-energy structures of CaB 2 H n compounds with n =2, 4, and 6 using PEGS simulations, refining the resulting structures with accurate DFT calculations. We find that the lowest-energy CaB 2 H 2 and CaB 2 H 4 crystal structures do not lie on the thermodynamically stable decomposition path but rather are unstable with respect to a decomposition pathway involving the previously proposed CaB 12 H 12 phase. We also predict a CaB 2 H 6 compound which forms a low-energy intermediate in the calcium borohydride decomposition pathway. This new reaction pathway is practically degenerate with decomposition into the CaB 12 H 12 phase. Similar calculations for magnesium borohydride show that a recently predicted MgB 2 H 6 phase does not form a stable intermediate in the decomposition pathway of Mg͑BH 4 ͒ 2 .

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Section: ͑1͒mentioning

confidence: 99%

Theoretical prediction of different decomposition paths forCa(BH4)2and

et al. 2010

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“…During the 1990s, the chemistry of metallaborane clusters, which can be viewed as borane clusters with one or more vertices replaced by a transition metal fragment, observed a flourishing development [ 36 , 37 , 38 , 39 , 40 ]. Their chemical and physical properties make them promising candidates for use in different areas such as catalysis [ 41 , 42 , 43 , 44 , 45 ] or materials science etc.…”

Section: Introductionmentioning

confidence: 99%

Polyhedral [M2B5] Metallaborane Clusters and Derivatives: An Overview of Their Structural Features and Chemical Bonding

2020

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A large number of metallaborane clusters and their derivatives with various structural arrangements are known. Among them, M2B5 clusters and derivatives constitute a significant class. Transition metals present in these species span from group 4 to group 7. Their structure can vary from oblatonido, oblatoarachno, to arachno type open structures. Many of these clusters appear to be hypoelectronic and are often considered as ‘rule breakers’ with respect to the classical Wade–Mingos electron counting rules. This is due to their unique highly oblate (flattened) deltahedral structures featuring a cross-cluster M−M interaction. Many theoretical calculations were performed to elucidate their electronic structure and chemical bonding properties. In this review, the synthesis, structure, and electronic aspects of the transition metal M2B5 clusters known in the literature are discussed. The chosen examples illustrate how, in synergy with experiments, computational results can provide additional valuable information to better understand the electronic properties and electronic requirements which govern their architecture and thermodynamic stability.

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“…In addition, although the transition metal fragments can be isolobal to borane fragments, they possess bonding capabilities that extend beyond this isolobal analogy. [15][16][17] The pioneering studies of Hawthorne and Grimes on the synthesis of metallacarboranes has paved the way for development in the field of metallaborane chemistry. Successively, the contributions of Fehlner, [4,6] Green, [18,19] Kennedy, [7,20] and others [9,21,22] have made significant impacts in this field, which has attracted significant attention owing to the uncommon structures involved as well as their unique bonding, uneven degrees of reactivity, and catalytic activity.…”

Section: Introductionmentioning

confidence: 99%

Metallaboranes from Metal Carbonyl Compounds and Their Utilization as Catalysts for Alkyne Cyclotrimerization

et al. 2014

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The photolysis of [M2(CO)10] (M=Re or Mn) with BH3⋅thf at room temperature yields arachno‐1 and 2, [(CO)8M2B2H6] (1: M=Re, 2: M=Mn). Both the compounds show a butterfly structure with seven skeletal electron pairs and 42 valence electrons. This result presents a new method for general access to low‐boron‐content metal–boron compounds without the cyclopentadienyl ligand at the metal centers. This new synthetic route is superior to the existing procedures because it avoids the use of [LiBH4] and metal polychlorides, for which the synthesis is very tedious. Compound 1 catalyzes the cyclotrimerization of a series of internal and terminal alkynes to yield mixtures of 1,3,5‐ and 1,2,4‐substituted benzenes. The reactivity of 1 with alkynes demonstrates for the first time that the introduction of the [B2H6] moiety into the [Re2(CO)10] framework significantly enhances the catalytic activity. Note that [Re2(CO)10] catalyzes the same set of alkynes under harsh conditions over a prolonged period of time. Quantum‐chemical calculations using DFT methods are applied to afford further insight into the electronic structure, stability, and bonding of 1 and 2. All the compounds are characterized by IR and 1H, 11B, and 13C NMR spectroscopy, and the geometry of 1 is established unambiguously through crystallographic analysis.

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The relevance of boranes and metallaboranes to the structures of p-block element nanoparticles

Cited by 17 publications

References 33 publications

Theoretical prediction of different decomposition paths forCa(BH4)2and

Theoretical prediction of different decomposition paths forCa(BH4)2and

Polyhedral [M2B5] Metallaborane Clusters and Derivatives: An Overview of Their Structural Features and Chemical Bonding

Metallaboranes from Metal Carbonyl Compounds and Their Utilization as Catalysts for Alkyne Cyclotrimerization

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