TY - JOUR
T1 - Substituent effects on iron boryl and borylene systems
T2 - Unusual reactivity and spectroscopic properties
AU - Addy, David A.
AU - Bates, Joshua I.
AU - Vidovic, Dragoslav
AU - Aldridge, Simon
PY - 2013/1/1
Y1 - 2013/1/1
N2 - Synthetic studies illustrate the crucial roles played by the steric and electronic properties of both the metal-bound ancillary ligands, L, and the boron-bound substituents, X, in the structural and reaction chemistry of boryl (LnMBX2) and borylene systems (LnMBX). Thus, the strong σ donor properties of trialkyl phosphine ligands are reflected in the fact that [CpFe(dmpe)(BOMes)]+ is shown to be a tractable, room-temperature stable species, whereas [CpFe(CO)2(BOMes)] + is not. Moreover the enhanced steric profile of dmpe (compared to a dicarbonyl ancillary ligand set) is shown to influence the propensity for electrophilic alkylation at boryl amino substituents, for example in CpFe(dmpe){B(NMe2)Cl} vs. CpFe(CO)2{B(NMe2)Cl}. Steric factors within the X substituent itself are also of key importance, and provide, for example, a rationale for the differing lability of NMe2 and NCy2 substituents in the presence of [Me3O][BF 4]. In addition, relatively subtle electronic factors within the B-X linkage have been shown to have a profound effect on spectroscopic properties, with the unusual chemical shift measured for [CpFe(dmpe)(BOMes)]+ being influenced by the presence of a heteroatom substituent featuring two lone pairs.
AB - Synthetic studies illustrate the crucial roles played by the steric and electronic properties of both the metal-bound ancillary ligands, L, and the boron-bound substituents, X, in the structural and reaction chemistry of boryl (LnMBX2) and borylene systems (LnMBX). Thus, the strong σ donor properties of trialkyl phosphine ligands are reflected in the fact that [CpFe(dmpe)(BOMes)]+ is shown to be a tractable, room-temperature stable species, whereas [CpFe(CO)2(BOMes)] + is not. Moreover the enhanced steric profile of dmpe (compared to a dicarbonyl ancillary ligand set) is shown to influence the propensity for electrophilic alkylation at boryl amino substituents, for example in CpFe(dmpe){B(NMe2)Cl} vs. CpFe(CO)2{B(NMe2)Cl}. Steric factors within the X substituent itself are also of key importance, and provide, for example, a rationale for the differing lability of NMe2 and NCy2 substituents in the presence of [Me3O][BF 4]. In addition, relatively subtle electronic factors within the B-X linkage have been shown to have a profound effect on spectroscopic properties, with the unusual chemical shift measured for [CpFe(dmpe)(BOMes)]+ being influenced by the presence of a heteroatom substituent featuring two lone pairs.
KW - Boron
KW - Boryl complex
KW - Borylene complex
KW - DFT calculations
KW - Halide abstraction
KW - Substitution
UR - http://www.scopus.com/inward/record.url?scp=84886598786&partnerID=8YFLogxK
U2 - 10.1016/j.jorganchem.2012.05.005
DO - 10.1016/j.jorganchem.2012.05.005
M3 - Article
AN - SCOPUS:84886598786
VL - 745-746
SP - 487
EP - 493
JO - Journal of Organometallic Chemistry
JF - Journal of Organometallic Chemistry
SN - 0022-328X
ER -