Effect of Solvent in the Reaction of Cp₂ZrH{(μ-H)₂BR₂} (R₂ = C₄H₈, C₈H₁₄) with B(C₆F₅)₃:  Formation of [HB(C₆F₅)₃]^- Salts of the Unsupported Hydrogen-Bridged Cations [(μ-H){Cp₂Zr(μ-H)₂BR₂}₂]⁺ (R₂ = C₄H₈, C₈H₁₄) and [Cp₂Zr(OEt

Abstract

Hydride abstraction reactions of the zirconocene cyclic organohydroborate complexes Cp2ZrH{(μ-H)2BR2} (R2 = C4H8, 1; C8H14, 2) with B(C6F5)3 were observed as a function of solvent. The reaction in poorly coordinating solvents, benzene and toluene, forms [HB(C6F5)3]- salts of Zr−H−Zr hydrogen-bridged cations [(μ-H){Cp2Zr(μ-H)2BR2}2]+ (R2 = C4H8, 3; C8H14, 4), in which there is no direct metal−metal bonding between the bridged metals. The unsupported hydrogen-bridged bond in complex 4 was cleaved when it was dissolved in the coordinating solvent THF to produce the neutral complex 2 and the ionic complex [Cp2Zr(THF){(μ-H)2BC8H14}][HB(C6F5)3]. In the coordinating solvent, diethyl ether, the salts of [Cp2Zr(OEt2)X]+[HB(C6F5)3]- (X = OEt, 5; {(μ-H)2BC8H14}, 6) consisting of zirconocene cations with coordinated solvent ligands were isolated. The formation of 5 involves hydride insertion from zirconium into the carbon oxygen bond of one the coordinated ethers, resulting in the liberation of ethane and the formation of an ethoxyl group coordinated to zirconium. The diethyl ether molecules in the cations 5 and 6 are weakly coordinated to Zr and are displaced in THF solution. Single-crystal X-ray structures of 3, 4, and 5 were determined.

On the alcoholysis of alkyl-aluminum(iii) alkoxy-NHC derivatives: reactivity of the Al-carbene Lewis pair versus Al-alkyl

“…Therefore it is instead assigned to the borohydride anion [HB(C6F5)3] -. 42,[48][49][50][51] The characteristic upfield shift of the resonances observed in the 19 F NMR spectrum (δ = -134.7, -161.0 and -165.1 ppm for [HB(C6F5)3]vs δ = -128.7, -141.6 and -159.9 ppm for B(C5F6)3) are also consistent with literature data for [HB(C6F5)3] -. 42,[48][49][50]52 [HB(C6F5)3]is most likely formed via β-hydride elimination from the isobutyl group with loss of isobutene which was identified in the 1 H NMR spectrum as a septuplet at δ = 4.75 ppm and a triplet at δ = 1.60 ppm.…”

Effect of solvent on reactions of Cp2Zr{(μ-H)2BHR}2 and Cp2ZrH{(μ-H)2BHR} (R=CH3, Ph) with B(C6F5)3

“…As time elapsed, compound 4 disappeared and crystals of compound 6 formed gradually inside the NMR tube. This result confirms the mechanism proposed previously [13].…”

“…A mechanism has been proposed for this reaction [13], however, no detailed NMR study has been performed. The time-elapsed 11 B NMR study of the reaction of Cp 2 ZrH{(l-H) 2 BHCH 3 } with B(C 6 F 5 ) 3 (Supplementary material Fig.…”

Reactivity of the bis(pentafluorophenyl)boranes ClB(C6F5)2 and [HB(C6F5)2]n towards late transition metal reagents

“…This thermal frailty mirrors that reported by Schlecht and Hartwig for (g 5 -C 5 H 4 Me)Mn(CO) 2 (H)BX 2 (X = Me, Cy). 17 Although it is difficult to plot the course of the thermal decomposition of 6 with any certainty, complexes of the type (g 5 -C 5 H 4 Me)Mn(CO) 2 (H)BX 2 are known to react via loss of the borane HBX 2 , 17 and this, together with the similarity in chemical shift and coupling constant for the predominant boron-containing decomposition product with those reported for [HB(C 6 F 5 ) 3 ] − (d B −25.5, 1 J BH = 80 Hz), 24 implies that initial loss of the HB(C 6 F 5 ) 2 fragment may feature in the mechanistic pathway. Additionally, IR monitoring of the decomposition process reveals that (g 5 -C 5 H 4 Me)Mn(CO) 3 is a major carbonyl containing product [m(CO) 2022 and 1941 cm −1 ].…”