(Methoxyborole)cobalt Complexes – Synthesis, Structures and Bonding

Abstract

Heating (η‐C4H4BCy)Co(CO)2I (Cy = cyclohexyl) in benzene in the presence of AlCl3 and subsequent methanolysis affords the cationic benzene complex [(η‐C4H4BOMe)Co(η‐C6H6)]+ (1). Under visible‐light irradiation, 1 reacts with MeCN and tBuNC to give the tris(ligand) complexes [(η‐C4H4BOMe)Co(L)3]+ [L = MeCN (2), tBuNC (4)]. A similar reaction with P(OMe)3 in MeCN affords [(η‐C4H4BOMe)Co(MeCN){P(OMe)3}2]+ (5). Cation 2 reacts with BPh4– in CH2Cl2 to give the zwitterionic arene complex (η‐C4H4BOMe)Co(η‐C6H5BPh3) (3). Reactions of 2 with TlCp and Tl(η‐9‐SMe2‐7,8‐C2B9H10) afford the sandwich compounds (η‐C4H4BOMe)CoCp (6) and (η‐C4H4BOMe)Co(η‐9‐SMe2‐7,8‐C2B9H10) (7). The structures of 3 and 7 were determined by X‐ray diffraction. The bonding in the borole complexes [(C4H4BR)Co(C6H6)]+ and (C4H4BR)CoCp (R = H, OMe) was compared with that in the cyclobutadiene analogues [(C4R4)Co(C6H6)]+ and (C4R4)CoCp (R = H, Me) using energy decomposition analysis.

(Tetramethylcyclobutadiene)cobalt complexes 10. Synthesis of arene complexes [(C4Me4)Co(arene)]+ and mechanism of the arene exchange reaction

“…1.454(6) Angle 26 that indicates a close resemblance of cyclobutadiene and borol ligands. The mechanism of the substitution reaction of benz ene in cation 2a and in its analog [( C 4 H 4 )Co( C 6 H 6 )] + (2a´) was analyzed by the density functional theory (DFT) using the BPBE and PBE functionals (Table 3).…”

Boron, aluminium, gallium, indium and thallium

“…153 A series methoxy borole cobalt complexes have been synthesised and their molecular structures determined by single crystal X-ray diffraction studies. 154 The unusual thermochromic and photochromic properties of pentaphenylboryl-lutidine adduct has been reported. 155 In related studies carbene stabilised adducts of chloro-tetraphenylboryl has been reported 156 as well as the synthesis of 1-bromo-2,3,4,5-tetraphenylborole has also been reported.…”

Zwitterionic Cobalt(I)–NHC Complexes with Tetraphenylborate Ligation: Synthesis, Characterization, and Reactivity

“…The cobalt center is coordinated with an IPr ligand and one of the phenyl groups of the anion [BPh 4 ] − in an η 6 19 The Co(η 6 -C 6 H 5 ) fragment in 2 has Co−C distances in the range 2.129(3)−2.211(4) Å. These distances are comparable to those in the reported zwitterionic cobalt(I) complexes, e.g., [(PMe 3 ) 2 Co((η 6 -C 6 H 5 )BPh 3 )] 12 (2.119−2.212 Å), [(py) 2 Co-((η 6 -C 6 H 5 )BPh 3 )] 13 (2.181−2.198 Å), [(R,R)-(Pr i DuPhos)-Co((η 6 -C 6 H 5 )BPh 3 )] 15 (2.071−2.298 Å), and [(η 5 -C 4 H 4 BOMe)Co((η 6 -C 6 H 5 )BPh 3 )] 14 (2.070−2.207 Å), though the coordination numbers of their cobalt centers are different. In molecule 2, the C(carbene)-Co-Phenyl(centroid) alignment with an angle of 153°deviates heavily from linearity.…”

“…Analog zwitterionic cobalt­(I) pyridine complex [(py) 2 Co­((η 6 -C 6 H 5 )­BPh 3 )] ( C ), however, was isolated by thermal decomposition of the cobalt­(II) complex [(py) 3 Co­(THF) 3 ]­[BPh 4 ] 2 . The zwitterionic cobalt­(I) borole complex [(η 5 -C 4 H 4 BOMe)­Co­((η 6 -C 6 H 5 )­BPh 3 )] ( D ) was obtained by recrystallization of [(η-C 4 H 4 BOMe)­Co­(NCMe) 3 ]­[BPh 4 ] in CH 2 Cl 2 . Recently, the Chirik group reported the preparation of the zwitterionic cobalt­(I) phosphine complex [(( R , R )-(Pr i DuPhos))­Co­((η 6 -C 6 H 5 )­BPh 3 )] ( E ) from the chloride abstraction reaction of [(( R , R )-(Pr i DuPhos))­Co­(μ-Cl)] 2 with NaBPh 4 .…”