Reactivity and Electronic Properties of a Ferrocene Molecule Bearing an N,C-Chelated BMes₂ Unit

Abstract

A dimesitylboron-functionalized benzimidazolylferrocene, B(2-ferrocenyl-N-Me-benzimidazolyl)Mes 2 (1), has been synthesized and fully characterized. The B−N bond in 1 was found to undergo a dynamic dissociation/association process in solution, leading to a dynamic exchange of the two mesityls bound to the boron atom and slow hydrolysis of 1 under ambient conditions. The hydrolyzed product 2-BMes(OH)-1-(N-methylbenzimidazol-2-yl)ferrocene (2) was isolated and characterized, in which the boron center has a trigonal-planar geometry with one of the mesityls being replaced by an OH − group. The photoisomerization process of the boron unit in 1 was fully inhibited by the low lying d−d/MLCT states of the ferrocene unit. Compound 1 can be oxidized readily by I 2 , forming the ferrocenium species [1 + ]I 3 -(3). NMR and EPR data for 3 indicated a notable spin delocalization through space from the Fe(III) center to a flanking mesityl group.

Chiral Organoborane Lewis Pairs Derived from Pyridylferrocene

“…We note that a similar hydrolysis process was observed by Wang et al. for an ortho ‐borylated benzimidazolylferrocene 7m. The smaller 5‐membered BN heterocycle appears to favor ring opening in Wang’s compound, whereas steric strain of the silylpyridyl group in 5‐Mes is necessary for ring opening and subsequent hydrolysis to occur ( 4‐Mes forms a stable heterocycle).…”

“…We postulated that if the B–N interaction in heterocycles of type D is sufficiently weakened then a thermally labile or frustrated planar chiral Lewis pair could be generated 7l. m…”

Enhancing electron affinity and tuning band gap in donor–acceptor organic semiconductors by benzothiadiazole directed C–H borylation

“…B–N cleavage has previously been shown to be the initial step in the hydrolysis of related boracycles. 20 No close H–H contact is observed in the structure of 2-BMe 2 due to a sulfur atom being located in the position adjacent to the equivalent benzothiadiazole C–H. Notably, the calculated structure of a methyl substituted borylatively fused thienyl–BT ( Fig.…”

Highly Emissive Far Red/Near‐IR Fluorophores Based on Borylated Fluorene–Benzothiadiazole Donor–Acceptor Materials

“…In contrast borylatively fused 2‐phenylpyridyl analogues are robust under aqueous base/raised temperature Suzuki–Miyaura cross‐coupling conditions . This disparity is attributed to the weaker BT→B dative bond, relative to the pyridyl→B dative bond, making the former more prone to ring opening by base, the initial step of the protodeboronation pathway …”

“…[7c] This disparity is attributed to the weaker BT!Bd ative bond, relative to the pyridyl!Bd ative bond, making the former more prone to ring openingb yb ase, the initial step of the protodeboronation pathway. [16] The successful Suzuki-Miyaura cross-coupling of 1-BAr 2 was achievedb yu sing milder reaction conditions with ah ighly active catalyst, Pd(PtBu 3 ) 2 , [17] that permitted ambientt emperature cross-coupling in just 30 min. The cross-coupling of 1-BPh 2 with F8(Bpin) 2 produced 7-BPh 2 in an excellent yield (84 %, Figure 3, top).…”