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Yang MC, Zhang ZF, Su MD. Insights into the Factors Controlling the H–H Bond Cleavage Reactions by Five-Membered G13/P (G13 = Group 13 Element) and B/G15 (G15 = Group 15 Element) Frustrated Lewis Pairs. Organometallics 2022. [DOI: 10.1021/acs.organomet.1c00599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Zhang ZF, Su MD. Theoretical investigations in the reactions of group 15 analogues of the monocationic five-membered N-heterocyclic carbenes: interplay of electrophilicity, basicity, and aromaticity governing the reactivity. NEW J CHEM 2022. [DOI: 10.1039/d1nj04631d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The nature of the group 15 analogs of the five-membered N-heterocyclic carbenes (G15-Rea; G15 = N, P, As, Sb, and Bi) was investigated by using various methodologies.
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Fan J, Quek S, Yang MC, Zhang ZF, Su MD, So CW. Reversible CO 2 activation by a N-phosphinoamidinato digermyne. Chem Commun (Camb) 2021; 58:1033-1036. [PMID: 34951421 DOI: 10.1039/d1cc05391d] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The N-phosphinoamidinato digermynes [LG̈e-G̈eL] (L = tBu2PNC(Ph)NAr, 4: Ar = 2,6-iPr2C6H3, 5: Ar = Ph) underwent reversible CO2 activation to form [LG̈eOC(O)G̈eL] (6: Ar = 2,6-iPr2C6H3, 7: Ar = Ph). Compound 7 was further reacted with diphenylacetylene and hexafluorobenzene, which proceeded through compound 5 in the first step, to form CO2, [LG̈eC(Ph) = C(Ph) G̈eL] (8), [LG̈eF] (9) and [LG̈eC6F5] (10), respectively.
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Abstract
The amidinatoamidosilylene [LSiNMe2] [1; L = PhC(NtBu)2] was reacted with B2Br4(SMe2)2 in toluene at room temperature to form the bis(silylene)tetrabromodiborane [L{Me2N}Si]2B2Br4 (2). It was then reacted with excess KC8 in tetrahydrofuran at room temperature to afford the bis(silylene)dibromodiborene [L{Me2N}Si]2B2Br2 (3).
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Zhang ZF, Yang MC, Su MD. Significant Insight into the Origin of Reaction Barriers Determining Dihydrogen Activation by G13-P-P (G13 = Group 13 Element) and G15-P-Ga (G15 = Group 15 Element) Frustrated Lewis Pairs. Inorg Chem 2021; 60:15253-15269. [PMID: 34570484 DOI: 10.1021/acs.inorgchem.1c01809] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The heterolytic cleavage of H2 by multiply bonded phosphorus-bridged G13-P-P-Rea (G13 = B, Al, Ga, In, and Tl) and G15-P-Ga-Rea (G15 = N, P, As, Sb, and Bi) frustrated Lewis pairs (FLPs) has been theoretically investigated using density functional theory calculations. For the above nine FLP-type molecules, our theoretical findings suggest that only Al-P-P-Rea, Ga-P-P-Rea, and In-P-P-Rea can undergo the energetically feasible H2 activation reaction from kinetic and thermodynamic viewpoints. Our study based on the activation strain model (ASM) reveals that gaining a better orbital overlap between G13-P-P-Rea and G15-P-Ga-Rea molecules and H2 affected the reaction barriers through the atomic radius of G13 and G15. According to our energy decomposition analysis-natural orbitals for chemical valence (EDA-NOCV) results, the bonding of these H2 activation reactions involving G13-P-P-Rea and G15-P-Ga-Rea is dominated by the donor-acceptor interaction (singlet-singlet interaction) rather than the electron-sharing interaction (triplet-triplet interaction). Moreover, our EDA-NOCV evidence reveals that the best description for the above bonding situations is the lone pair(G15) → σ*(H2) interaction rather than the empty p-π-orbital(G13) ← σ(H2) interaction. In particular, the findings in this work based on theoretically calculated geometries and the corresponding relative free energies of the stationary points combined with the results from the above sophisticated methods nicely agree with the famous Hammond postulate.
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Zhang ZF, Su MD. Insights into the Factors Controlling the Origin of Activation Barriers in Group 13 Analogues of the Four-Membered N-Heterocyclic Carbenes. ACS OMEGA 2021; 6:22272-22283. [PMID: 34497916 PMCID: PMC8412915 DOI: 10.1021/acsomega.1c02958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 08/13/2021] [Indexed: 06/13/2023]
Abstract
The mechanisms of C-H bond insertion and alkene cycloaddition were investigated theoretically using five model systems: group 13 analogues of the four-membered nucleophilic N-heterocyclic carbenes (NHCs) (1E; E = group 13 element). The theoretical findings indicate that, except for 1B with H2C=CH2, these four-membered NHCs undergo insertion and [1 + 2] cycloaddition reactions with difficulty because their activation barriers are quite high (31 kcal/mol). The theoretically confirmed chemical inertness of the four-membered NHCs 1Ga and 1In might explain why they have been experimentally detected at room temperature. Additionally, our theoretical observations indicate that the reactivity of these four-membered NHCs featuring a central group 13 element follows the order 1B ≫ 1Al > 1Ga > 1In > 1Tl. The theoretical examination suggests that the smaller the atomic radius of the central group 13 element in the four-membered NHC analogue is, the larger the aromaticity of this carbenic molecule is, the higher the basicity of this carbenic molecule in nature is, the larger its nucleophilic attack on other oncoming molecules is, the smaller the barrier heights of its C-H bond insertion and [1 + 2] cycloaddition reactions will be, the higher its exothermicities for these products will be, and thus, the greater its reactivity will be. Moreover, the present theoretical findings reveal that the reactivity of 1B is governed by its highest occupied molecular orbital, a nonbonding sp2 lone pair orbital. In contrast, the reactivity of the four heavier 1E' (E' = Al, Ga, In, and Tl) molecules is mainly determined by their lowest unoccupied molecular orbital, a vacant p-π orbital. The conclusions gained from this study allow many predictions to be made.
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Fan J, Yang MC, Hooper TJN, Su MD, So CW. Diboron-Carbene Complexes Derived from a Geminal Dianion. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Fan J, Mah JQ, Yang MC, Su MD, So CW. A N-Phosphinoamidinato NHC-Diborene Catalyst for Hydroboration. J Am Chem Soc 2021; 143:4993-5002. [PMID: 33448848 DOI: 10.1021/jacs.0c12627] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The use of the N-phosphinoamidinato NHC-diborene catalyst 2 for hydroboration is described. The N-phosphinoamidine tBu2PN(H)C(Ph)═N(2,6-iPr2C6H3) was reacted with nBuLi in Et2O to afford the lithium derivative, which was then treated with B2Br4(SMe2)2 in toluene to form the N-phosphinoamidinate-bridged diborane 1. It was reacted with the N-heterocyclic carbene IMe (:C{N(CH3)C(CH3)}2) and excess potassium graphite at room temperature in toluene to give the N-phosphinoamidinato NHC-diborene compound 2. It can stoichiometrically activate ammonia-borane and carbon dioxide. It also showed catalytic capability. A 2 mol % portion of 2 catalyzed the hydroboration of carbon dioxide (CO2) with pinacolborane (HBpin) in deuterated benzene (C6D6) at 110 °C (conversion >99%), which afforded the methoxyborane [pinBOMe] (yield 97.8%, TOF 33.3 h-1) and the bis(boryl) oxide [(pinB)2O]. In addition, 5 mol % of 2 catalyzed the N-formylation of secondary and primary amines by carbon dioxide and pinacolborane to yield the N-formamides (average yield 91.6%, TOF 25.9 h-1). Moreover, 2 showed chemoselectivity toward catalytic hydroboration of carbonyl compounds. In mechanistic studies, the B═B double bond in compound 2 activated the substrates, the intermediates of which then underwent hydroboration with pinacolborane to yield the products and regenerate catalyst 2.
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Li TL, Zhang ZF, Su MD. Reactivity of dicationic N-heterocyclic chalcogen carbene analogues with methane and ethene: a theoretical investigation. Phys Chem Chem Phys 2021; 23:2419-2429. [PMID: 33459738 DOI: 10.1039/d0cp06173e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reactions of chalcogen N-heterocyclic carbenic (NHC) dications [(Dipp2DAB)M2+, M = O, S, Se, and Te, and Dipp2DAB = 1,4-(2,6-diisopropyl)phenyl-1,4-diaza-1,3-butadiene] with methane and ethene are investigated by the density functional theory. The activation energies and reaction enthalpies are analyzed by the energy decomposition analysis (EDA) to understand the reactivity of the reactions. Calculations show that the oxide carbenic dication (Dipp2DAB)O2+ reactant has a pair of rather unbalanced O-N bonds due to the combined effects of the smallness of the central O atom and the bulkiness of the two Dipp ligands surrounding the DAB ring, suggesting the oxide reactant is much less stable than the chalcogenide ones. Because of its unique characteristics, the oxide carbenic dication distinguishes itself from the rest of the chalcogen family. The differences between oxides and chalcogenides of the chalcogen family complexes well known in inorganic chemistry are also observed in this theoretical investigation. This work further reveals that the reasons for the distinctive characteristics between oxide and chalcogenide complexes are due to the fundamental fact that the 2s and 2p atomic orbitals are more amenable to hybridization than those of higher valences, and the mixing of the former valence orbitals results in much smaller atoms than the latter.
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Zhang ZF, Su MD. Mechanistic insights into the insertion and addition reactions of group 13 analogues of the six-membered N-heterocyclic carbenes: interplay of electrophilicity, basicity, and aromaticity governing the reactivity. RSC Adv 2021; 11:20070-20080. [PMID: 35479910 PMCID: PMC9033959 DOI: 10.1039/d1ra02703d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 05/28/2021] [Indexed: 11/21/2022] Open
Abstract
Three fundamental concepts (aromaticity/basicity/electrophilicity), being heavily used in modern chemistry, have been applied in this work to study the chemical reactivity of six-membered-ring group 13 N-heterocyclic carbenes (G13-6-Rea; G13 = group 13 elements) using density functional theory (BP86-D3(BJ)/def2-TZVP). G13-6-Rea is isolobal to benzene. Two model reactions have been used in the present study: the insertion reaction of G13-6-Rea with methane and the [1 + 2] cycloaddition reaction of G13-6-Rea with ethene. Our theoretical analysis reveals that the chemical reactivity of B-6-Rea, Al-6-Rea, and Ga-6-Rea is governed by their HOMO (the sp2-σ lone pair orbital on the G13 element), and thus they can be considered nucleophiles. Conversely, the chemical behavior of In-6-Rea and Tl-6-Rea is determined by their LUMO (the vacant p-π orbital on the G13 element), and thus they can be considered electrophiles. On the basis of the VBSCD (valence bond state correlation diagram) model and ASM (activation strain model), this theoretical evidence demonstrates that the origin of activation barriers for the above model reactions is due to the atomic radius of the pivotal group 13 element in the six-membered-ring of G13-6-Rea. Accordingly, our theoretical conclusions suggest that the lower the atomic number and the smaller the atomic radius of the G13 atom, the higher the aromaticity of the six-membered-ring of G13-6-Rea and the smaller the singlet–triplet energy splitting ΔEst of this N-heterocyclic carbene analogue, which will facilitate its chemical reactions. The theoretical findings originating from this study allow many predictions in experiments to be made. On the basis of sophisticated theoretical models, the theoretical study demonstrated that the atomic radius of a group 13 element in a six-membered-ring NHC analogue plays an important role in determining its chemical reactivity.![]()
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Leong BX, Teo YC, Condamines C, Yang MC, Su MD, So CW. A NHC-Silyliumylidene Cation for Catalytic N-Formylation of Amines Using Carbon Dioxide. ACS Catal 2020. [DOI: 10.1021/acscatal.0c03795] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Yang MC, Su MD. A theoretical study of the reactivity of ethene and benzophenone with a hyper-coordinated alkene containing a so-called E=E (E = C, Si, Ge, Sn, and Pb) unit. Dalton Trans 2020; 49:12842-12853. [PMID: 32902537 DOI: 10.1039/d0dt01914c] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reactivity of a reported hyper-coordinated alkene (Rea-E; Rea = reactant; E = group 14 element) featuring a central E[double bond, length as m-dash]E moiety was theoretically analyzed using DFT (density functional theory) and the EDA-NOCV (energy decomposition analysis-natural orbitals for chemical valence) method. M06-2X/def2-SVP and B3LYP-D3/def2-SVP results demonstrate that five Rea-E molecules have an energy minimum as their structures have no imaginary frequency. Theoretical examinations based on three types of bond order calculations (Wiberg, Mayer, and Fuzzy), the LOL (localized orbital locator) analyses, Lewis structures and the NBO (natural bond orbital) analyses suggest that a very weak central Si-Si single bond and an extremely weak central Ge-Ge single bond, rather than a double bond, are present in the Rea-Si and Rea-Ge molecules, respectively. On the other hand, no bond is found between the two central group 14 atoms in Rea-C, Rea-Sn, and Rea-Pb. The theoretical investigation demonstrates that the reactivity of the Rea-E compound decreases in the order Rea-Si > Rea-Ge > Rea-C, a trend that results from the differences in the atomic radii of the group 14 elements. Carbon has the smallest atomic radius in the group 14 family, causing steric crowding between Rea-C and other attacking species. This circumstance, in turn, increases the activation energies of its addition reactions and renders these reactions energetically infeasible. For the cyclic product of Rea-Ge, the theoretical evidence reveals that the comparatively large atomic radius of Ge induces the weakest Pauli repulsions and the smallest overlap integrals between Rea-Ge and the other doubly bonded molecules. This situation, in turn, makes the overall cyclization reaction of Rea-Ge endothermic. As a result, only the silicon-centered molecule, Rea-Si, can undergo the [2 + 2] cycloaddition reactions with doubly bonded molecules without kinetic or thermodynamic difficulty, which agrees well with the available experimental findings.
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Liu C, Zhu K, Han W, Liu X, Zhang ZF, Su MD, Wu D, Li Y. Formation of Alkynylgermyl-Substituted Germylenes via a Catenation of Ge Atoms. Inorg Chem 2020; 59:10123-10128. [DOI: 10.1021/acs.inorgchem.0c01244] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Zhang ZF, Li TL, Su MD. Understanding the reactivity of carbene-analogous phosphane complexes with group 13 elements as a central atom: a theoretical investigation. NEW J CHEM 2020. [DOI: 10.1039/d0nj01708f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The reactions of carbenic cations (PtBu3)2M+ (M = B, Al, Ga, In, and Tl) with methane and ethene are studied using density functional theory.
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Zhang ZF, Li TL, Su MD. Correction: Understanding the reactivity of carbene-analogous phosphane complexes with group 13 elements as a central atom: a theoretical investigation. NEW J CHEM 2020. [DOI: 10.1039/d0nj90117b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Correction for ‘Understanding the reactivity of carbene-analogous phosphane complexes with group 13 elements as a central atom: a theoretical investigation’ by Zheng-Feng Zhang et al., New J. Chem., 2020, 44, 12815–12826, DOI: 10.1039/D0NJ01708F.
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Yang MC, Su MD. A mechanistic study of the activation of small molecules (H 2 and C 2H 2) by group 14 analogues of selenophene. NEW J CHEM 2020. [DOI: 10.1039/d0nj01077d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this study, the reactivity influenced by group 14 elements (E = C, Si, Ge, Sn, and Pb), which are used as substituents in heterocyclic five-membered rings, was theoretically examined by using density functional theory (B3PW91/def2-SVP).
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Leong BX, Lee J, Li Y, Yang MC, Siu CK, Su MD, So CW. A Versatile NHC-Parent Silyliumylidene Cation for Catalytic Chemo- and Regioselective Hydroboration. J Am Chem Soc 2019; 141:17629-17636. [DOI: 10.1021/jacs.9b06714] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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Zhang SL, Yang MC, Su MD. A computational study to determine whether substituents make E 13[triple bond, length as m-dash]nitrogen (E 13 = B, Al, Ga, In, and Tl) triple bonds synthetically accessible. RSC Adv 2019; 9:12195-12208. [PMID: 35515843 PMCID: PMC9063501 DOI: 10.1039/c9ra00318e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 04/10/2019] [Indexed: 12/16/2022] Open
Abstract
This study theoretically determines the effect of substituents on the stability of the triple-bonded L–E13N–L (E13 = B, Al, Ga, In, and Tl) compound using the M06-2X/Def2-TZVP, B3PW91/Def2-TZVP, and B3LYP/LANL2DZ+dp levels of theory. Five small substituents (F, OH, H, CH3 and SiH3) and four large substituents (SiMe(SitBu3)2, SiiPrDis2, Tbt (
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C6H2-2,4,6-{CH(SiMe3)2}3) and Ar* (C6H3-2,6-(C6H2-2,4,6-i-Pr3)2)) are used. Unlike other triply bonded L–E13P–L, L–E13As–L, L–E13Sb–L and L–E13Bi–L molecules that have been studied, the theoretical findings for this study show that both small (but electropositive) ligands and bulky substituents can effectively stabilize the central E13N triple bond. Nevertheless, these theoretical observations using the natural bond orbital and the natural resonance theory show that the central E13N triple bond in these acetylene analogues must be weak, since these E13N compounds with various ligands do not have a real triple bond. This study theoretically determines the effect of substituents on the stability of the triple-bonded L–E13N–L (E13 = B, Al, Ga, In, and Tl) compound using the M06-2X/Def2-TZVP, B3PW91/Def2-TZVP, and B3LYP/LANL2DZ+dp levels of theory.![]()
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Yang MC, Su MD. A Theoretical Study on the Stability of PtL 2 Complexes of Endohedral Fullerenes: The Influence of Encapsulated Ions, Cage Sizes, and Ligands. ACS OMEGA 2019; 4:3105-3113. [PMID: 31459530 PMCID: PMC6649168 DOI: 10.1021/acsomega.8b02469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 01/04/2019] [Indexed: 06/10/2023]
Abstract
The {η2-(X@C n )}PtL2 complexes possessing three kinds of encapsulated ions (X = F-, Ø, Li+), three various ligands (L = CO, PPh3, NHCMe), and twelve cage sizes (C60, C70, C72, C74, C76, C78, C80, C84, C86, C90, C96, C100) are theoretically examined by using the density functional theory (M06/LANL2DZ). The present computational results demonstrate that the backward-bonding orbital interactions, rather than the forward-bonding orbital interactions, play a dominant role in the stability of {η2-(X@C n )}PtL2 complexes. Additionally, our theoretical study shows that the presence of the encapsulated Li+ ion can greatly improve the stability of {η2-(X@C n )}PtL2 complexes, whereas the existence of the encapsulated F- ion can heavily reduce the stability of {η2-(X@C n )}PtL2 complexes. Moreover, the theoretical evidence strongly suggests that the backward-bonding orbital interactions as well as the stability increase in the order {η2-(X@C n )}Pt(CO)2 < {η2-(X@C n )}Pt(PPh3)2 < {η2-(X@C n )}Pt(NHCMe)2. As a result, these theoretical observations can provide experimental chemists a promising synthetic direction.
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Huang Y, Wang X, Li Y, Yang MC, Su MD, Zhu H. A self-hydrosilylation of phosphanylhydrosilylalkynes promoted by B(C 6F 5) 3? An experimental and mechanistic study. Chem Commun (Camb) 2019; 55:1494-1497. [PMID: 30648174 DOI: 10.1039/c8cc09022j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Phosphanylhydrosilylalkynes Me2HSiC[triple bond, length as m-dash]CPAr2 (Ar = Ph, 1a; 4-MeC6H4, 1b) were synthesized, which reacted with B(C6F5)3 to produce alkenes [(E)-(C6F5)3BCH[double bond, length as m-dash]C(PAr2)SiMe2]2 (2a and 2b) and (Z)-(C6F5)2BCH[double bond, length as m-dash]C(PAr2)SiMe2(C6F5) (3a and 3b). The formation of 2a (or 2b) involved a Wrackmeyer's SiHMe2 migration followed by Si-H addition across the C[triple bond, length as m-dash]C bond, whereas, that of 3a (or 3b) involved a similar mechanism with a further C6F5 migration. The B(C6F5)3-promoted reaction of the Si-centered geminal H and C[triple bond, length as m-dash]C groups is thus realized, which may be considered as a self-hydrosilylation. Mechanistic studies by both variable temperature NMR spectroscopy and DFT calculations were accomplished.
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Zhang ZF, Su MD. The mechanistic investigations of photochemical decarbonylations and oxidative addition reactions for M(CO) 5 (M = Fe, Ru, Os) complexes. RSC Adv 2019; 9:2626-2640. [PMID: 35520498 PMCID: PMC9059829 DOI: 10.1039/c8ra07669c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 12/07/2018] [Indexed: 11/21/2022] Open
Abstract
The mechanisms for the photochemical CO-dissociation and the oxidative addition reactions are studied theoretically using three model systems: M(CO)5 (M = Fe, Ru, and Os) and the CASSCF/Def2-SVP (fourteen-electron/ten-orbital active space) and MP2-CAS/Def2-SVP//CASSCF/Def2-SVP methods. The structures of the intersystem crossings and the conical intersections, which play a decisive role in these CO photo-extrusion reactions, are determined. The intermediates and the transition structures in either the singlet or triplet states are also computed, in order to explain the reaction routes. These model studies suggest that after the irradiation of Fe(CO)5 with UV light, it quickly loses one CO molecule to generate a 16-electron iron tetracarbonyl, in either the singlet or the triplet states. It is found that the triplet Fe(CO)4 plays a vital role in the formation of the final oxidative addition product, Fe(CO)4(H)(SiMe3), but the singlet Fe(CO)4 plays a relatively minor role in the formation of the final product. However, its vacant coordination site interacts weakly with solvent molecules ((Me3)SiH) to yield the alkyl-solvated iron complexes, which are detectable experimentally. The theoretical observations show that Ru(CO)5 and Os(CO)5 have similar photochemical and thermal potential energy profiles. In particular, this study demonstrates that the oxidative addition yield for Fe is much greater than those for its Ru and Os counterparts, under the same chemical conditions.
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Yang MC, Su MD. Theoretical investigations of the reactivity of neutral molecules that feature an MM (M = B, Al, Ga, In, and Tl) double bond. NEW J CHEM 2019. [DOI: 10.1039/c9nj01294j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The geometry, the electronic structure and the reactivity of compounds that feature a central MM (M = group 13 element) double bond with two sterically bulky ligands (L1 = tBu2MeSi and L2 = NHCiPr), L1L2MML1L2 (Rea-MM) are studied at the B3LYP-D3(BJ)/def2-SVP level of theory.
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Khoo S, Cao J, Yang MC, Shan YL, Su MD, So CW. Frontispiece: Synthesis of a Dimeric Base-Stabilized Cobaltosilylene Complex for Catalytic C−H Bond Functionalization and C−C Bond Formation. Chemistry 2018. [DOI: 10.1002/chem.201885464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Khoo S, Cao J, Yang MC, Shan YL, Su MD, So CW. Synthesis of a Dimeric Base-Stabilized Cobaltosilylene Complex for Catalytic C−H Bond Functionalization and C−C Bond Formation. Chemistry 2018; 24:14329-14334. [DOI: 10.1002/chem.201803410] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Indexed: 11/05/2022]
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Lu JS, Yang MC, Su MD. Is It Possible To Prepare and Stabilize Triple-Bonded Thallium≡Antimony Molecules Using Substituents? ACS OMEGA 2018; 3:10163-10171. [PMID: 31459144 PMCID: PMC6644622 DOI: 10.1021/acsomega.8b00643] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 07/05/2018] [Indexed: 06/10/2023]
Abstract
The M06-2X/Def2-TZVP, B3PW91/Def2-TZVP, and B3LYP/LANL2DZ+dp levels of theory were used to investigate the effect of substituents on the stability of the triple-bonded RTl≡SbR molecule. For comparison, small groups (F, OH, H, CH3, and SiH3) and sterically bulky substituents, (Ar* (=C6H3-2,6-(C6H2-2,4,6-i-Pr3)2), Tbt (=C6H2-2,4,6-{CH(SiMe3)2}3), SiiPrDis2, and SiMe(SitBu3)2), were chosen for the present study. The density functional theory results indicate that the triple-bonded RTl≡SbR compounds with small ligands are transient intermediates, so their experimental detections should be extremely difficult. Nevertheless, the theoretical observations demonstrate that only the bulkier ligands can effectively stabilize the central Tl≡Sb triple bond. In addition, the valence-electron bonding model reveals that the bonding characters of the triple-bonded RTl≡SbR species possessing sterically bulky groups can be represented as RTl ← SbR. Nevertheless, on the basis of the natural resonance theory, the natural bond orbital, and the charge decomposition analysis, the theoretical observations suggest that the Tl≡Sb triple bond in the acetylene analogues, RTl≡SbR, should be very weak.
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