B⁺ in the Coordination Sphere of Two Transition Metals

Abstract

The first cationic metallaborylene complexes, [{(OC)5Mn}2(μ‐B)][BArf4] and [{(η5‐C5H4R)(OC)2Fe}2(μ‐B)][BArf4] (R=H, Me; see structure) were synthesized by halide abstraction from bridged haloborylene complexes and structurally characterized. The boron atom is located in the coordination sphere of two transition‐metal centers and is highly unsaturated.

OP04.07: Diagnostic correlation between 2D and 3D ultrasound at 20–22 weeks in fetal evaluation. Preliminary results

“…The short MnB distances (1.8812(14) and 1.8809(14) Å) are in agreement with related terminal borylene complex 4 (1.810(1) Å) and are significantly shorter than those of precursor 3 b (1.976(9)–2.039(11) Å) 10h. This result suggests two full borylene‐like MnB bonds, similar to these found in the cationic species [{(η 5 ‐C 5 H 4 Me)(OC) 2 Fe} 2 B] + 8c…”

“…In addition, such extremely deshielded resonances are known to be indicative of M‐B‐M moieties, in which a two‐coordinate boron atom is linked solely to metal centers. Similarly low‐field‐shifted 11 B NMR signals were found for the cationic complexes [{(OC) 5 Mn} 2 (μ‐B)][BAr F 4 ] ( δ =224.9 ppm), [{(η 5 ‐C 5 H 5 )(OC) 2 Fe} 2 (μ‐B)][BAr F 4 ] ( δ =191.2 ppm), and [{(η 5 ‐C 5 H 4 Me)(OC) 2 Fe} 2 (μ‐B)][BAr F 4 ] ( δ =193.7 ppm),8c as well as the silylborylene complex [(OC) 5 CrBSi(SiMe 3 ) 3 ] ( δ =204.3 ppm) and the metalloborylene complex [{(η 5 ‐C 5 Me 5 )(OC) 2 FeBCr(CO) 4 ] ( δ =204.6 ppm) 11…”

Dehydropolymerization of H3B·NMeH2 To Form Polyaminoboranes Using [Rh(Xantphos-alkyl)] Catalysts

“…As discussed later, the lack of high-field signals in the 1 H NMR spectrum, very low field chemical shift of the 11 B resonance and mass-spectral data all indicate that there are no hydrides associated with the complex. The Rh-B distances are both short [1.880(8) and 1.862(8) Å], and comparable to closely related iron 58 . The Rh-B distances are shorter than that measured in Rh(k 3 -P,O,P-Xantphosi Pr)(Bpin) [1.981(4) Å; pin = pinacol] 27a which has a formal covalent Rh-B single bond, are longer than those in monometallic complexes with M=B bonds, e.g.…”

Preparation and Characterization of a π‐Conjugated Donor–Acceptor System Containing the Strongly Electron‐Accepting Tetraphenylborolyl Unit

“…Because of the absence of a band resulting from this transition, solutions of 1 appear yellow and are distinct from the usually deeply colored solutions of known borole derivatives (e.g. solutions of pentaphenylborole are blue: λ max =560 nm) . According to time‐dependent density functional theory (TD‐DFT) calculations at the CAM‐B3LYP/6‐31G(d) level, the very small oscillator strength ( f =0.0153) of the HOMO–LUMO transition likely accounts for the absence of the corresponding band in the UV/Vis spectrum of 1 (see Supporting Information for details).…”

“…solutions of pentaphenylborole are blue: l max = 560 nm). [18,19] Ac-cordingt ot ime-dependent density functional theory (TD-DFT) calculations at the CAM-B3LYP/6-31G(d)l evel, the very small oscillator strength( f = 0.0153) of the HOMO-LUMO transition likely accounts for the absence of the corresponding band in the UV/Vis spectrum of 1 (see Supporting Information for details). The absorption at l max = 447 nm is dominated by electronic transitions from HOMOÀ1t ot he LUMO, which are localized mainly on the carbazole and the borole, respectively (Figure 3).…”