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Synthesis of CCC-type osmium chelates from triynes. a Triynes as ligand precursors to access CCC-type chelates with three metal–carbon σ bonds. b X-ray structure of the cation of chelate 1 drawn with 50% probability (phenyl groups in PPh3 are omitted for clarity). Selected bond distances (Å) and angles (deg): Os–C1 1.840(7), Os–C4 2.108(7), Os–C7 2.040(8), C1–C2 1.406(10), C2–C3 1.394(10), C3–C4 1.395(9), C4–C5 1.390(10), C5–C6 1.395(10), C6–C7 1.366(10), Os–C1–C2 129.3(6), C1–C2–C3 108.3(6), C2–C3–C4 112.1(6), C3–C4–Os 117.1(5), C1–Os–C4 73.2(3), Os–C4–C5 116.6(5), C4–C5–C6 113.6(7), C5–C6–C7 115.5(7), C6–C7–Os 118.9(5), C7–Os–C4 75.4(3)
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Although the formation of metal–carbon σ bonds is a fundamental principle in organometallic chemistry, the direct bonding of one organic molecule with one metal center to generate more than two metal–carbon σ bonds remains a challenge. Herein, we report an aromaticity-driven method whereby multiyne chains are used to construct three metal–carbon σ...
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A fundamental bonding model in coordination and organometallic chemistry is the synergic, donor–acceptor interaction between a metal and a neutral π-acceptor ligand in which the ligand σ donates to the metal, which π back-bonds to the ligand. This interaction typically involves a metal with an electron-rich, mid-, low- or even negative oxidation st...
Citations
... However, one notable omission is that 11Ccarbolong complexes with a planar carbon-chain ligand have not been synthesized so far, although a non-planar one with one of the two M-C bonds in the six-membered ring locating vertical to the metallapentalene plane was reported 55 . Besides, the other issue that needs to be mentioned is that the interesting and important M≡C bond, which exhibits rich reactivities, has not yet appeared in a system larger than 7C-carbolong framework (metallapentalynes) 48,50,55 . ...
... The 31 P{ 1 H} NMR spectrum exhibits two signals at 12.55 and −9.39 ppm, attributed to the phosphonium group and PPh 3 ligands, respectively, consistent with its planar skeleton. The chemical shift of C1H proton is observed at 12.29 ppm, near to those of the orthoprotons of osmapentalenes [38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53] . ...
Carbolong complexes are one of the primary types of metallaaromatics, and they include metallapentalynes and metallapentalenes. A series of 7C-10C and 12C-carbolong complexes with planar ligand skeletons respectively containing 7-10 and 12 carbon atoms in their backbones, have been previously reported. Herein, two classes of strained substances, metallabenzyne-fused metallapentalenes and metallabenzene-fused metallapentalynes, were prepared, both representing 11C-carbolong complexes with a planar carbon-chain ligand. Furthermore, the former type is also the carbolong derivatives containing a metallabenzyne skeleton, another primary metallaaromatic framework. Metallabenzyne-fused metallapentalenes show versatile reactivities, and the most interesting one is the metal carbyne bond shift from a 6-membered to a more strained 5-membered ring, affording the above-mentioned metallabenzene-fused metallapentalyne. This work makes carbolong chemistry more complete, and provides a method to achieve metallabenzynes, which is anticipated to concurrently advance the development of these two types of metallaaromatics.
... The 13 C NMR signals of 3MR are observed at δ 202.2 (C2), 140.3 (C1), and the signal of C11 is located at δ 134.8, which are consistent with the metallacyclopropenylidene moiety. [23] The functional group compatibility of this formal [2+1] cycloadditions is investigated as well. As shown in Figure 2, a broad scope of alkynes with either electron-withdrawing or electron-donating substituents in different positions of benzene rings perform successfully, resulting in complexes 3-26 in moderate yields. ...
... [24] Due to the electron-withdrawing nature of triphenyl phosphonium group and cationic metal center, the acidity of OsCH in intermediate C is drastically increased, thus promoting the deprotonation process [23,25] and formation of intermediate D bearing a cyclic metal vinylidene unit. Subsequently, the formal [2+1] addition leads to the generation of intermediate E by forming a new C-C bond and re-coordination of carbonyl to metal center. ...
Comprehensive Summary
Metallacyclopentadienes play a vital role in transition‐metal mediated and catalyzed cycloaddition reactions of alkynes. Though versatile reactions of metallacyclopentadienes with alkynes have been disclosed, [2+1] cycloadditions of metallacyclopentadienes and alkynes have never been discovered. In present work, we report the formal [2+1] cycloadditions of a metallacyclopentadiene unit with a broad scope of commercial alkynes, providing a facile strategy to construct tetracyclic conjugated compounds. The deuterated experiment indicates a metal vinylidene intermediate has been involved in [2+1] cycloaddition. Moreover, the electrophilic substitution reaction of the tetracyclic conjugated compound with the aid of density functional theory (DFT) calculated Fukui functions is investigated. These tetracyclic conjugated compounds exhibit broad absorption spectra in the whole visible region which could be employed as potential photovoltaic materials.
... Actually, metallapentalyne can be also synthesized by a one-pot reaction of multiynes with OsCl 2 (PPh 3 ) 3 , which is also an aromaticitydriven process [100]. The reaction barrier for the rate-determining step is 23.1 kcal mol −1 (Fig. 7f). ...
... Computational method, B3LYP/6-311++G(d,p) (LanL2DZ). (f) Gibbs energy profiles of the aromaticity-driven cyclization reaction of the multiyne chain with OsCl 2 (PPh 3 ) 3[100]. Computational method, PCM(dichloromethane)-TPSS/6-31G(d)(SDD)//B3LYP/6-31G(d)(SDD). ...
... Both π-and σ-aromaticity endow molecules with aromatic stabilization, leading to products with lower energies. Therefore, aromaticity-driven reactions play a crucial role in synthetic chemistry 15,16 . Currently, π-aromaticity-driven strategies are well known to guide the synthesis of aromatic compounds, but reactions induced by σ-aromaticity have seldom been reported 17,18 . ...
... In principle, metallacyclobutadienes tend to undergo ring expansion or ring opening. In fact the transformation of 2a to 3a may represent the first observation of a structurally welldefined ring contraction of metallacyclobutadiene to metallacyclopropene. Analogous complexes as η 2 -1-metalla(methylene)cyclopropenes (η 2 -allenyl complexes) have been reported, which have usually been synthesized by transformations from η 2 -alkyne complexes [44][45][46] , or reactions of metal sources with unsaturated substrates, such as allenes and alkynes 15 . ...
... Compounds S-1, S-2 and L1 were synthesized according to the literature 15 . ...
π-Aromaticity is an important driving force in directing the synthesis of aromatic compounds; in contrast, reactions induced by σ-aromaticity are uncommon. Here we report a strategy based on π- and σ-aromaticity relays to realize the structurally defined ring contraction of metallacyclobutadiene to metallacyclopropene. This reaction involves the release of the π-antiaromaticity of metallacyclobutadiene to afford a π-aromatic intermediate, followed by ring reclosure to generate σ-aromatic metallacyclopropene. The ring opening–reclosing mechanism and versatile switching of the aromaticity of the metallacyclic species are supported by experimental results and theoretical calculations. This work demonstrates the importance of aromaticity relay with the successive decrease of energy in reactions and will stimulate efforts in exploiting the vital role of aromaticity in synthetic chemistry. Reactions induced by σ-aromaticity are uncommon compared with those induced by π-aromaticity. Now, a π- and σ-aromaticity relay strategy is developed to realize the ring contraction of metallacyclobutadiene to metallacyclopropene. This reaction involves the release of π-antiaromaticity to afford a π-aromatic intermediate, followed by ring reclosure to form σ-aromatic metallacyclopropene.
... In recent years, we have reported a series of readily accessible metal-bridged bicyclic/ polycyclic aromatics, namely carbolong complexes, which are stable in air and moisture (23)(24)(25). The addition of osmium carbynes (in carbolong complexes) and alkynes gave rise to an intriguing family of d π -p π conjugated systems, which function as excellent electron transport layer materials in organic solar cells (26,27). ...
Conjugated polymers usually require strategies to expand the range of wavelengths absorbed and increase solubility. Developing effective strategies to enhance both properties remains challenging. Herein, we report syntheses of conjugated polymers based on a family of metalla-aromatic building blocks via a polymerization method involving consecutive carbyne shuttling processes. The involvement of metal d orbitals in aromatic systems efficiently reduces band gaps and enriches the electron transition pathways of the chromogenic repeat unit. These enable metalla-aromatic conjugated polymers to exhibit broad and strong ultraviolet–visible (UV–Vis) absorption bands. Bulky ligands on the metal suppress π–π stacking of polymer chains and thus increase solubility. These conjugated polymers show robust stability toward light, heat, water, and air. Kinetic studies using NMR experiments and UV–Vis spectroscopy, coupled with the isolation of well-defined model oligomers, revealed the polymerization mechanism.
... Compounds 1 and 2 were synthesized according to previously published procedures. 40,41 Column chromatography was performed on neutral alumina (200−300 mesh) in air. NMR spectroscopic experiments were performed on a Bruker AVIII-400 ( 1 H, 400.1 MHz; 13 C, 100.6 MHz; 31 P, 162.0 MHz) spectrometer, a Bruker AVIII-500 ( 1 H, 500.2MHz; ...
Low-work-function (WF) metals (including silver (Ag), aluminum (Al), and copper (Cu)) used as external cathodes in inverted perovskite solar cells (PSCs) encounter oxidation caused by air exposure and halogen-diffusion-induced corrosion, which threaten the long-term stability of the device. The cathode interlayer (CIL) has shown promise in reducing the metal WF and thus boosting the device power conversion efficiency (PCE). However, it remains a challenge for current CIL materials to enable high-WF metals (e.g., Au) to be used as cathodes to achieve PSCs with a superior PCE and long-term stability. Here, we use a series of synthesized (carbolong-derived) organometallic complexes as CILs to tune the electrode WF in inverted PSCs. Density functional theory calculations and surface characterizations show that the organometallic complexes that contain anions and cations are prone to form anion−cation dipoles on the metal surface, hence drastically reducing the metal's WF. Photovoltaic devices based on a Ag cathode, which was modified with these organometallic complexes, received a boosted PCE up to 21.29% and a remarkable fill factor that reached 83.52%, which are attributed to the dipole-enhanced carrier transport. The environmental stability of PSCs was further improved after employing Au as a cathode with these organometallic complexes, and the modified devices exhibited no efficiency loss after 4080 h storage measurements.
... Alternatively, metallapentalynes can be synthesized directly from organics with metal precursors. Xia and coworkers found that triynes with a hydroxyl group reacted with MCl 2 (PPh 3 ) 3 (M = Os or Ru) in the presence of PPh 3 to give a series of metallapentalynes 37-42 (Scheme 15) [56,57]. When X = CH 2 CH 2 , the alkyne-coordinated intermediate was isolable [56]. ...
... Xia and coworkers found that triynes with a hydroxyl group reacted with MCl 2 (PPh 3 ) 3 (M = Os or Ru) in the presence of PPh 3 to give a series of metallapentalynes 37-42 (Scheme 15) [56,57]. When X = CH 2 CH 2 , the alkyne-coordinated intermediate was isolable [56]. It is worth pointing out that complexes 41 and 42 are the first metallapentalynes based on a second-row transition metal [57]. ...
Due to the linear property around an acetylenic carbon, the introduction of such an atom to a small cycle would result in high ring strain. Currently, the smallest isolated rings are five-membered, including metallacycloalkynes and metallapentalynes. Both types contain at least one unusual small bond angle around the acetylenic carbon, thus exhibiting abnormal reactivities. This feature article gives a comprehensive overview on these two kind complexes. The synthesis and reactivities are extensively described, the source of stability is presented, and the future prospect is discussed. The article aims to provide a better development for the chemical diversity of five-membered metallacycloalkynes and metallapentalynes.
... Recently, Xia and coworkers documented a series of five-membered cyclic metal carbyne complexes, i.e., osmapentalynes [47][48][49][50][51] and ruthenapentalynes [52]. The carbine-carbon bond angles in the metallapentalynes are around 130°, which are much smaller than those of the acyclic metal carbynes (180°). ...
... Recently, Xia and coworkers documented a series of five-membered cyclic metal carbyne complexes, i.e., osmapentalynes [47][48][49][50][51] and ruthenapentalynes [52]. The carbine-carbon bond angles in the metallapentalynes are around 130 • , which are much smaller than those of the acyclic metal carbynes (180 • ). ...
The acyclic organic alkynes and carbyne bonds exhibit linear shapes. Metallabenzynes and metallapentalynes are six- or five-membered metallacycles containing carbynes, whose carbine-carbon bond angles are less than 180°. Such distortion results in considerable ring strain, resulting in the unprecedented reactivity compared with acyclic carbynes. Meanwhile, the aromaticity of these metallacycles would stabilize the ring system. The fascinating combination of ring strain and aromaticity would lead to interesting reactivities. This mini review summarized recent findings on the reactivity of the metal–carbon triple bonds and the aromatic ring system. In the case of metallabenzynes, aromaticity would prevail over ring strain. The reactions are similar to those of organic aromatics, especially in electrophilic reactions. Meanwhile, fragmentation of metallacarbynes might be observed via migratory insertion if the aromaticity of metallacarbynes is strongly affected. In the case of metallapentalynes, the extremely small bond angle would result in high reactivity of the carbyne moiety, which would undergo typical reactions for organic alkynes, including interaction with coinage metal complexes, electrophilic reactions, nucleophilic reactions and cycloaddition reactions, whereas the strong aromaticity ensured the integrity of the bicyclic framework of metallapentalynes throughout all reported reaction conditions.
... The osmapentalyne reactants such as 1a (Fig. 1a) were synthesized and characterized (See Supplementary Figs. [40][41][42][43] 39 . A solution of the complex (1a) was treated with HCl·Et 2 O solution in dichloromethane (DCM), producing a carbyne triple bond shifted product (2a) (Fig. 1a). ...
... Concerning the scope of the osmapentalyne (Fig. 4), a series of reactant osmapentalynes (1b-1g) were synthesized by the treatment of carbon ligands (L2-L7) with multiyne chains with OsCl 2 (PPh 3 ) 3 and PPh 3 , the different substituents at different positions appear not to affect the reaction (3,(31)(32)(33)(34)(35)(36). For instance, the R′ substituent can be styryl (3), phenyl (31)(32)(33), thienyl (34) or hydrogen (35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46), and the Y group can be CH 2 (31,34), O (32,35) or C(COOMe) 2 (33,36). The structures of all the above complexes were confirmed by NMR spectroscopy, EA and HRMS ( Supplementary Figs. ...
The metal-carbon triple bonds and carbon-carbon triple bonds are both highly unsaturated bonds. As a result, their reactions tend to afford cycloaddition intermediates or products. Herein, we report a reaction of M≡C and C≡C bonds that affords acyclic addition products. These newly discovered reactions are highly efficient, regio- and stereospecific, with good functional group tolerance, and are robust under air at room temperature. The isotope labeling NMR experiments and theoretical calculations reveal the reaction mechanism. Employing these reactions, functionalized dπ-pπ conjugated systems can be easily constructed and modified. The resulting dπ-pπ conjugated systems were found to be good electron transport layer materials in organic solar cells, with power conversion efficiency up to 16.28% based on the PM6: Y6 non-fullerene system. This work provides a facile, efficient methodology for the preparation of dπ-pπ conjugated systems for use in functional materials.
... We thus envisaged that constraining transition metal carbynes into small rings would lead to the activation of the M≡C bond and offer access to the 1,3-dipolar cycloadditions with azides. On the basis of our previous investigation of metallapentalynes (25)(26)(27)(28)(29), the synthesis of the activated M≡C bond within the tricyclic ring system was then targeted, in the hope of obtaining suitable starting material to generate desired tetracyclic aromatic motifs through metalla-click reactions. We reacted complex 1 (27) with K 2 CO 3 (5 eq) at 40°C for 2 days, which afforded a green solution, from which complex 2 was isolated in 84% yield ( Fig. 2A). ...
... Complex 2 was characterized by nuclear magnetic resonance (NMR) spectroscopy and high-resolution mass spectrometry (HRMS). In the 13 C NMR spectrum, the signal for the carbyne carbon of complex 2 was observed at 337.2 parts per million (ppm), which is close to the reported value for osmapentalynes (25)(26)(27)(28). The solid-state structure of complex 2 was further confirmed by single-crystal x-ray diffraction via counter anion exchange of Cl with BPh 4 ( Fig. 2B; see the Supplementary Materials for details). ...
... The x-ray diffraction study revealed that 2 has a fused metallapentalyne core structure with good planarity, as reflected by the small mean deviation (0.034 Å) from the least-squares plane through Os1, O1, and C1─C9. The bond distance of the Os1─C1 [1.888(5) Å] and the bond angle at the sp-hybridized carbon atom [129.7(3)°] are comparable to those of previously reported metallapentalynes (25)(26)(27)(28)(29). The corresponding bond distances within the metallacycles, together with the planarity of the metallatricycle, indicate electronic delocalization within the metallatricycle in 2. It is noted that 2 is the first cyclic metal carbyne in tricyclic metalla-aromatics with a bridgehead metal. ...
The never-ending pursuits for exploring aromatic molecular architectures result in the large libraries of aromatics with fascinating structures, which have greatly broadened the scope of aromaticity. Despite extensive efforts that have been paid to develop aromatic frameworks, the construction of polycyclic aromatics that share a bridgehead atom with more than three rings has never been accomplished. Here, an unprecedented family of aromatics, in which a metal center shared by 4 five-membered aromatic rings, has been achieved by using the metalla-click reactions with excellent yields and remarkable regioselectivity. The distinctive tetracyclic aromatics exhibit a broad absorption in the ultraviolet-visible near-infrared region and excellent thermal stability in air, enabling their potential applications in photoelectric materials and biomedicine. This study now makes it possible to incorporate four aromatic rings with one common sharing metal center by a straightforward strategy that would promote further development of previously unknown polycyclic complex motifs in aromatic chemistry.
