Chemistry of Dimetallaboranes Derived from the Reaction of [Cp*MCl₂]₂with Monoboranes (M = Ru, Rh; Cp* = η⁵-C₅Me₅)

Abstract

In a single step, from [Cp*RuCl 2 ] 2 (Cp* ) η 5 -C 5 Me 5 ) and Li [BH 4 ], nido-1,2-(Cp*Ru) 2 (µ-H) 2 B 3 H 7 , 1, is produced in high yield. Addition of BH 3 ‚THF to 1 results in conversion to nido-1,2-(Cp*Ru) 2 (µ-H)B 4 H 9 , 2. Reaction of BH 3 ‚THF directly with [Cp*RuCl 2 ] 2 yields a mixture of 1 and 2. In two steps, a rhodium analogue, nido-2,3-(Cp*Rh) 2 B 3 H 7 , 9, is accessible by the reaction of [Cp*RhCl 2 ] 2 and Li [BH 4 ] to exclusively produce (Cp*Rh) 2 B 2 H 6 , 8, which adds BH 3 ‚THF to give 9 as the major product in a mixture. Reaction of BH 3 ‚THF directly with [Cp*RhCl 2 ] 2 yields the chloro derivative of 9, nido-1-Cl-2,3-(Cp*Rh) 2 B 3 H 6 , 11, in high yield via the intermediate positional isomer, nido-3-Cl-1,2-(Cp*Rh) 2 B 3 H 6 , 10. With high concentrations of Co 2 (CO) 8 , 1 reacts with Co 2 (CO) 8 to give nido-1-(Cp*Ru)-2-(Cp*RuCO)-3-Co(CO) 2 (µ 3 -CO)B 3 H 6 , 3, whereas low concentrations permit competitive degradation of 1 to yield arachno-(Cp*Ru)(CO)(µ-H)B 3 H 7 , 4. On the other hand, reaction of 11 with Co 2 (CO) 8 gives closo-1-Cl-6-{Co(CO) 2 }-2,3-(Cp*Rh) 2 (µ 3 -CO)B 3 H 3 , 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)B 3 H 4 , 5, whereas thermolysis of 2 results in loss of hydrogen and formation of pileo-2,3-(Cp*Ru) 2 B 4 H 8 , 6, with a BH-capped square pyramidal structure. Finally, 6 reacts with Fe 2 (CO) 9 to yield pileo-6-Fe(CO) 3 -2,3-(Cp*Ru) 2 (µ 3 -CO)B 4 H 4 , 7, with a BH-capped octahedral cluster structure. The overall isolated yield of 7, formed in four steps from [Cp*RuCl 2 ] 2 , is ≈50% and evidences good control of reactivity.

Synthesis and characterization of diruthenaborane analogues of pentaborane(11) and hexaborane(10)

“…5). Though six-vertex clusters with capped-square pyramidal geometry [18] and corresponding seven-vertex clusters with capped octahedral geometry [13,21] are known, 7 is the first example with…”

“…As structurally characterized examples of diruthenaheteroboranes are rare, we became interested in investigating the use of different chalcogen sources for the generation of new types of cluster systems. Upon the availability of one of the very common and reactive metallaborane nido-[1,2-(Cp*RuH) 2 B 3 H 7 ] (nido-1), which is very prone to cluster expansion reaction, [13] we thought to utilize this as a precursor for the synthesis of new ruthenaheteroboranes.…”

[(Ni‐Ni‐Ni)@(Ge9)2]4−: A Linear Triatomic Nickel Filament Enclosed in a Dimer of Nine‐Atom Germanium Clusters

“…Furthermore, as with 2, the corresponding monomeric cluster [Cp*RuB 4 H 10 Ru-Cp*] is also known. [25] The charge of 4À of 1 can be understood as the sum of the charges of [Ni@(Ge 9 2À , as well as each half of 1, hypo-electronic because a deltahedron with 10 vertices should have 2n + 2 = 22 (n = 10) cluster-bonding electrons according to Wades rules. [26] The reason for the deviation is clearly the shape of the cluster which differs greatly from the shape expected for a 10-atom deltahedron (a bicapped square antiprism).…”

Metallaboranes of the Early Transition Metals: Direct Synthesis and Characterization of [{(η5‐C5Me5)Ta}2BnHm] (n=4, m=10; n=5, m=11), [{(η5‐C5Me5)Ta}2B5H10(C6H4CH3)], and [{(η5‐C5Me5)TaCl}2B5H11]

“…[11] The development of metallaborane chemistry has followed a similar pathway, and new species are often isolated under conditions that favor the thermodynamic product, either through thermolysis or by simple metathesis reactions between a preformed polyborane anion and transition-metal halides. [3a-b, 12] Fehlner et al have studied reactions between cyclopentadienyl transition-metal halides [Cp*MCl n ] (Cp*= h 5 -C 5 Me 5 ) and monoborane reagents BH 3 ·thf, LiBH 4 ·thf, and BHCl 2 ·SMe 2 ,which often afford metallaboranes (M = Cr, [13] Mo, [14] W, [15] Re, [16] Ru, [17] Co, [18] Rh, [19] and Ir. [20] ) in modest to high yield under mild conditions.…”