10388-28-0Relevant academic research and scientific papers
Chemistry of Dimetallaboranes Derived from the Reaction of [Cp*MCl2]2 with Monoboranes (M = Ru, Rh; Cp* = η5-C5Me5)
Lei, Xinjian,Shang, Maoyu,Fehlner, Thomas P.
, p. 1275 - 1287 (1999)
In a single step, from [Cp*RuCl2]2 (Cp* = η5-C5Me5) and Li[BH4], nido-1,2-(Cp*Ru)2(μ-H)2B3H 7, 1, is produced in high yield. Addition of BH3·THF to 1 results in conversion to nido-1,2-(Cp*Ru)2(μ-H)B4H9, 2. Reaction of BH3·THF directly with [Cp*RuCl2]2 yields a mixture of 1 and 2. In two steps, a rhodium analogue, nido-2,3-(Cp*Rh)2B3H7, 9, is accessible by the reaction of [Cp*RhCl2]2 and Li[BH4] to exclusively produce (Cp*Rh)2B2H6, 8, which adds BH3·THF to give 9 as the major product in a mixture. Reaction of BH3·THF directly with [Cp*RhCl2]2 yields the chloro derivative of 9, nido-1-Cl-2,3-(Cp*Rh)2B3H6, 11, in high yield via the intermediate positional isomer, nido-3-Cl-1,2-(Cp*Rh)2B3H6, 10. With high concentrations of Co2(CO)8, 1 reacts with Co2(CO)8 to give nido-1-(Cp*Ru)-2-(Cp*RuCO)-3-Co(CO)2(μ 3-CO)B3H6,3, whereas low concentrations permit competitive degradation of 1 to yield arachno-(Cp*Ru)(CO)(μ-H)B3H7, 4. On the other hand, reaction of 11 with Co2(CO)8 gives closo-1-Cl-6-{Co(CO)2}-2,3-(Cp*Rh)2(μ 3-CO)B3H3, 12. Mild thermolysis of 3 results in loss of hydrogen and the formation of closo-6-Co(CO)2-2,3-(Cp*Ru)2(μ-CO)(μ 3-CO)B3H4, 5, whereas thermolysis of 2 results in loss of hydrogen and formation of pileo-2,3-(Cp*Ru)2B4H8, 6, with a BH-capped square pyramidal structure. Finally, 6 reacts with Fe2(CO)9 to yield pileo-6-Fe(CO)3-2,3-(Cp*Ru)2(μ 3-CO)B4H4, 7, with a BH-capped octahedral cluster structure. The overall isolated yield of 7, formed in four steps from [Cp*RuCl2]2, is ≈50% and evidences good control of reactivity.
Transfer reactions involving boron. XX. Disproportionation reactions of alkyl-, alkoxy-, and haloboranes
Pasto,Balasubramaniyan,Wojtkowski
, p. 594 - 598 (1969)
The solution redistribution equilibria of borane with alkylboranes, alkoxyboranes, haloboranes, and arylmercaptoboranes have been studied. The results obtained with the various systems are discussed individually and compared with each other and, when available, with gas-phase and other data appearing in the literature. The redistribution of trialkylboranes with borane in tetrahydrofuran produces a mixture of mono-, di-, and trialkylboranes and borane, the first two being the predominant products. Complicating the systems are the presence of five hydrogen-bridged monomer-dimer equilibria. The equilibrium constants for these equilibria have been determined for the n-propyl- and isopropylborane systems. The reaction of 1 or 2 mol of alcohols with 1 mol of borane produces dialkoxyboranes in kinetically controlled reactions. The dialkoxyboranes undergo slow redistribution reactions to give mixtures of borane and di- and trialkoxyboranes. Similarly, trialkyl borates and borane undergo slow disproportionation reactions. The redistribution equilibrium constants are identical, within experimental error, for primary and secondary alkoxyborane systems; however, the t-butoxyborane equilibrium constant is significantly different. The rate of attainment of equilibrium is markedly dependent on the structure of the alkoxy group. Boron trichloride reacts with borane to give either mono- or dichloroborane depending on the stoichiometry of the starting reagents, whereas boron trifiuoride does not react with borane.
The Reaction of cis-1,2-Dichloroethylene with Borane in Tetrahydrofuran. The Supply of Monochloroborane in Tetrahydrofuran Solution
Arase, Akira,Hoshi, Masayuki,Masuda, Yuzuru
, p. 299 - 300 (1981)
In the reaction of cis-1,2-dichloroethylene with borane in THF at 20 deg C for 2 h, about 94percent of borane was converted to monochloroborane.The resulting solution was stable at 0 deg C for several hours.
Synthesis of novel molybdaboranes from (η5-C5R5)MoCl(n) precursors (R = H, Me; N = 1,2,4)
Aldridge, Simon,Shang, Maoyu,Fehlner, Thomas P.
, p. 2586 - 2598 (1998)
Reaction of Cp*MoCl4(1), or (Cp*MoCl2)2 (2), Cp* = η5-C5Me5, with BH3·THF ultimately generates the Mo(II) cluster (Cp*Mo)2B5H9 (7), together with the Mo(III) species (Cp*MoCl)2B4H10, 4. Prereduction of 2 before reaction with BH3·THF yields only 7. The structure of 4 consists of two Cp*Mo units bridged by two chlorides and a [B2H5(B2H5)]2- ligand in which the two diboron moieties are connected by a B-B-B three center bond. Closer inspection of the reaction by 11B and 1H NMR reveals the existence of three intermediate species (Cp*MoCl)2B2H6 (3), (Cp*MoCl)2B3H7 (5), and (Cp*Mo)2(B2H6)2 (6). Each of these species has been characterized spectroscopically, and crystal structures have been obtained for 3 and 5. Compound 3 features molybdenum centers bridged by two chlorides and an ethane-like [B2H6]2- ligand such that the B-B bond is perpendicular to the Mo-Mo bond. Replacing one terminal H by [B2H5] generates 4. The structure of 5 is based on a trigonal bipyramidal Mo2B3 core, and the molecule is electronically unsaturated although the Mo-Mo distance (3.096 A?) precludes the existence of multiple bonding between the metal centers. 5 exists as a relatively stable molecule despite having too few electrons and too few atoms to adopt a capped structure based on a polyhedron with fewer vertexes. Comparison of MO descriptions of the electronic structure of 5 with that of the later transition metal species (Cp*Co)2B3H7 (8) shows that this stabilization is derived from the appropriate energy match between Cp*Mo and borane based orbitals which elevates the energy of the Mo-B antibonding LUMO, a cluster orbital which would normally be filled, into the region of unoccupied orbitals. The concentration vs time behavior for the final products 4 and 7, for the intermediates 3, 5, and 6, for the monoboron species BH3·THF and BH2Cl, and selected non-boron containing species is used to define a pathway for the molybdaborane cluster condensation. With 1, use of LiBH4 as the monoboron source yields 6 as the primary product via 3 as an intermediate, whereas prereduction of 2 with [Et3BH]- results in the formation of 7. The varied cluster building abilities of BH3·THF vs LiBH4 originate in the differing reduction and coordination properties of the two monoboranes. Investigation of the analogous Cp = η5-C5H5 system reveals similar chemistry albeit simpler and on a shorter time scale.
