Hydroboration of the (C₅Me₅)Fe(1,2-Ph₂PC₆H₄) System To Derive Hydridoborate and Hydridosilicate Complexes

Abstract

The synthesis and characterization of hydridoborate and hydridosilicate iron half-sandwich complexes derived from activation of HBpin with an N2-bridged dimer [Cp*Fe­(1,2-Ph2PC6H4)]2(μ-N2) (1, Cp* = C5Me5 –) are reported. The reaction appears to proceed by hydroboration of the Fe-based metallacycle to give a 16-electron iron­(II)-hydride intermediate, presumably Cp*FeH­(Ph2PC6H4Bpin), which is able to capture a HBpin or H2SiPhR (R = Ph or H) molecule through Fe-H cooperation, resulting in Cp*Fe­(η3-H2Bpin)­(Ph2PC6H4Bpin) (2) and Cp*Fe­(η3-H2SiHPhR)­(Ph2PC6H4Bpin) (R = Ph, 3a; H, 3b) complexes. Density functional theory calculations showed that those complexes exhibit intriguing Fe–H–E nonclassical features (E = B or Si), and the nature of Fe-η3-H2E interactions can be rationalized as unusual hydrido-borane and -silane complexes, that is, (H)­Fe-η2-H–E. This has been shown by straightforward substitution of the HBpin moiety of hydridoborate with silane, affording hydridosilicate complexes.

Bimetallic H2 Addition and Intramolecular Caryl–H Activation Mediated by an Iron–Zinc Hydride

“…The aryl iron(II) precursor Cp*Fe(1,2-Cy 2 PC 6 H 4 )(N 2 ) (1) was prepared by treating 1,2-Cy 2 PC 6 H 4 Li with [Cp*FeCl] 2 in THF at −30 °C. 50 It was isolated as brown solids in 71% yields and the 31 P NMR spectrum of 1 exhibits a singlet at 4.1 ppm. Crystallographic analysis of 1 confirmed a half-sandwich iron− nitrogen complex having a cyclometalated 1,2-Cy 2 PC 6 H 4 − ligand (Figure S53).…”

“…The aryl iron­(II) precursor Cp*Fe­(1,2-Cy 2 PC 6 H 4 )­(N 2 ) ( 1 ) was prepared by treating 1,2-Cy 2 PC 6 H 4 Li with [Cp*FeCl] 2 in THF at −30 °C . It was isolated as brown solids in 71% yields and the 31 P NMR spectrum of 1 exhibits a singlet at 4.1 ppm.…”

Ammonium and Phosphonium Salts Containing Monoanionic Iron(II) Half-Sandwich Complexes [Fe(η5-Cp*)X2]− (X = Cl − I)

“…Seminal work was published in 1985 by Kölle, who described the generation of [Fe(η 5 -Cp*)Br] (Cp* = C 5 Me 5 ) from LiCp* and [FeBr 2 (DME)] in THF at −80 • C [2]. The corresponding chlorido complex [Fe(η 5 -Cp*)Cl], which suffers from the same thermal lability, is particularly popular as a Cp*Fe + source [3][4][5][6][7][8][9][10]. The analogous complex containing the pentamethylcyclopentadienyl-related and O-donorfunctionalised ligand C 5 Me 4 [(CH) 2 (OCH 2 CH 2 ) 3 OMe], whose oligoether chain is suitable for intramolecular chelation, was reported to be thermally stable in THF solution up to room temperature, although this complex could not be isolated [11].…”

Si–H Bond Activation and Dehydrogenative Coupling of Silanes across the Iron–Amide Bond of a Bis(amido)bis(phosphine) Iron(II) Complex

“…Based on the observed activation of B–H bonds by 1 , we expected Si–H bonds to exhibit commensurate reactivity due to their similar bond dissociation energies . Traditional pathways toward silane activation by first-row metals include oxidative additions, − multicenter η 2 -Si–H and η 3 -Si–H binding interactions, − electrophilic activation, and the generation of more exotic binding modes via activation of multiple Si–H bonds (e.g., the Co-silicide reported by Tilley et al). , Examples of Si–H activation across metal–ligand bonds are rare, ,− and activation across metal–N bonds are limited to imido complexes of Ta, Sc, Ti, and Co. , …”