π‐Bonding in Complexes of Benzannulated Biscarbenes, ‐germylenes, and ‐stannylenes: An Experimental and Theoretical Study

Hahn, F. Ekkehardt; Zabula, Alexander V.; Pape, Tania; Hepp, Alexander; Tonner, Ralf; Haunschild, Robin; Frenking, Gernot

doi:10.1002/chem.200801128

Cited by 53 publications

(42 citation statements)

References 57 publications

(24 reference statements)

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“…Transition-metal complexes with monodentate NHSn ligands have not yet been isolated, but complexes with biand polydentate NHSn ligands could be synthesized and structurally characterized. [59] They show end-on coordination of the stannylenes, which could, however, be enforced by the bridging of the monomers. In contrast, the first TM complexes with monodentate NHPb ligands were recently reported by Grimme, Hahn, and co-workers.…”

Section: Resultsmentioning

confidence: 99%

Transition‐Metal Complexes of Tetrylones [(CO)₅W‐E(PPh₃)₂] and Tetrylenes [(CO)₅W‐NHE] (E=C–Pb): A Theoretical Study

Nhung

Frenking

2012

Chemistry A European J

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Quantum chemical calculations at the BP86/TZVPP//BP86/SVP level are performed for the tetrylone complexes [W(CO)(5) -E(PPh(3))(2)] (W-1 E) and the tetrylene complexes [W(CO)(5)-NHE] (W-2 E) with E=C-Pb. The bonding is analyzed using charge and energy decomposition methods. The carbone ligand C(PPh(3) ) is bonded head-on to the metal in W-1 C, but the tetrylone ligands E(PPh(3))(2) are bonded side-on in the heavier homologues W-1 Si to W-1 Pb. The W-E bond dissociation energies (BDEs) increase from the lighter to the heavier homologues (W-1 C: D(e) =25.1 kcal mol(-1); W-1 Pb: D(e) =44.6 kcal mol(-1)). The W(CO)(5) ←C(PPh(3))(2) donation in W-1 C comes from the σ lone-pair orbital of C(PPh(3))(2), whereas the W(CO)(5) ←E(PPh(3))(2) donation in the side-on bonded complexes with E=Si-Pb arises from the π lone-pair orbital of E(PPh(3))(2) (the HOMO of the free ligand). The π-HOMO energy level rises continuously for the heavier homologues, and the hybridization has greater p character, making the heavier tetrylones stronger donors than the lighter systems, because tetrylones have two lone-pair orbitals available for donation. Energy decomposition analysis (EDA) in conjunction with natural orbital for chemical valence (NOCV) suggests that the W-E BDE trend in W-1 E comes from the increase in W(CO)(5) ←E(PPh(3))(2) donation and from stronger electrostatic attraction, and that the E(PPh(3))(2) ligands are strong σ-donors and weak π-donors. The NHE ligands in the W-2 E complexes are bonded end-on for E=C, Si, and Ge, but side-on for E=Sn and Pb. The W-E BDE trend is opposite to that of the W-1 E complexes. The NHE ligands are strong σ-donors and weak π-acceptors. The observed trend arises because the hybridization of the donor orbital at atom E in W-2 E has much greater s character than that in W-1 E, and even increases for heavier atoms, because the tetrylenes have only one lone-pair orbital available for donation. In addition, the W-E bonds of the heavier systems W-2 E are strongly polarized toward atom E, so the electrostatic attraction with the tungsten atom is weak. The BDEs calculated for the W-E bonds in W-1 E, W-2 E and the less bulky tetrylone complexes [W(CO)(5) -E(PH(3))(2)] (W-3 E) show that the effect of bulky ligands may obscure the intrinsic W-E bond strength.

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Section: Resultsmentioning

confidence: 99%

Transition‐Metal Complexes of Tetrylones [(CO)₅W‐E(PPh₃)₂] and Tetrylenes [(CO)₅W‐NHE] (E=C–Pb): A Theoretical Study

Nhung

Frenking

2012

Chemistry A European J

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“…It has been initially claimed that the excellent ligand features of NHCs were due to their strong σ-donation abilities [ 32 – 33 ]. However, experimental and computational evidences have revealed non-negligible π-acceptor properties [ 34 – 38 ]. In recent years, several strategies have successfully been developed for tuning the π-acidity of NHCs by changing substitution and structural patterns, such as the size of the backbone ring [ 39 – 41 ], variation of the α-heteroatoms [ 7 ], anti-Bredt NHCs [ 42 – 43 ], mesoionic NHCs [ 44 – 47 ], ylide stabilized carbenes [ 48 – 51 ] and other [ 52 – 55 ].…”

Section: Introductionmentioning

confidence: 99%

Direct estimate of the internal π-donation to the carbene centre within N-heterocyclic carbenes and related molecules

Andrada

Holzmann

Hamadi

et al. 2015

Beilstein J. Org. Chem.

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SummaryFifteen cyclic and acylic carbenes have been calculated with density functional theory at the BP86/def2-TZVPP level. The strength of the internal X→p(π) π-donation of heteroatoms and carbon which are bonded to the C(II) atom is estimated with the help of NBO calculations and with an energy decomposition analysis. The investigated molecules include N-heterocyclic carbenes (NHCs), the cyclic alkyl(amino)carbene (cAAC), mesoionic carbenes and ylide-stabilized carbenes. The bonding analysis suggests that the carbene centre in cAAC and in diamidocarbene have the weakest X→p(π) π-donation while mesoionic carbenes possess the strongest π-donation.

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“…These distances are shorter than those in the stanna(II)bicyclo[3.3.0]octanes 1 and 2 and reflect enhanced Lewis acidity of the tin atoms in the compounds 5 – 8 . Such a strengthening of intramolecular donor–acceptor interactions by complexation to a transition‐metal moiety has previously been observed for the related stannabicyclo[3.3.0]octane derivatives MeN(CH 2 CH 2 O) 2 SnW(CO) 5 ,5 t BuN(CH 2 CH 2 S) 2 SnCr(CO) 5 ,8b and PhP(CH 2 CH 2 S) 2 SnCr(CO) 5 · C 5 H 5 N,8c as well as for a pentacarbonylmolybdenum complex of a benzannulated bis(stannylene) 8d. The Sn–Cr [2.6232(8) Å ( 6 )], Sn–W [2.7743(2), 2.7746(5) Å ( 5 , 7 )], and Sn–Fe [2.4875(5), 2.4976(5) Å ( 8 )] distances are comparable to corresponding distances reported in the literature 5,9,10.…”

Section: Resultsmentioning

confidence: 53%

Trapping Molecular SnBr₂(OH)₂ by Tin Alkoxide Coordination: Syntheses and Molecular Structures of [MeN(CH₂CMe₂O)₂SnBr₂]₂·SnBr₂(OH)₂ and RN(CH₂CMe₂O)₂SnL [R = Me, n‐Octyl; L = Lone Pair, Cr(CO)₅, W(CO)₅, Fe(CO)₄, Br₂]

et al. 2012

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The synthesis of the intramolecularly coordinated stannylenes and their transition-metal complexes of the type RN(CH 2 CMe 2 O) 2 SnL [1: L = lone pair, R = Me; 2: L = lone pair, R = n-octyl; 5: L =W(CO) 5 , R = Me; 6: L = Cr(CO) 5 , R = Me; 7: L =W(CO) 5 , R = n-octyl; 8: L = Fe(CO) 4 , R = Me], and of the tin(IV) compounds RN(CH 2 CMe 2 O) 2 SnBr 2 (9: R = Me), [a] 3463 [MeN(CH 2 CMe 2 O) 2 SnBr 2 ] 2 ·SnBr 2 (OH) 2 (10) and spiro-[RN(CH 2 CMe 2 O) 2 ] 2 Sn (3: R = Me; 4: R = n-octyl) is reported. The compounds were characterized by elemental analyses, 1 H, 13 C, 119 Sn, and 119 Sn magic-angle spinning (5, 6) NMR spectroscopy, electrospray mass spectrometry, and singlecrystal X-ray diffraction analysis. exhibit superior crystallization properties. They also enabled the isolation of an unprecedented trinuclear Sn-O cluster. www.eurjic.org 3469 119 Sn MAS Spectroscopy: The 119 Sn MAS NMR spectra were recorded with a Bruker Avance III 400 spectrometer using cross polarization and high-power proton decoupling [conditions: 3.7 μS (90°) pulse, 2 ms contact time, 10 s recycle delay]. For compounds Eur.

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π‐Bonding in Complexes of Benzannulated Biscarbenes, ‐germylenes, and ‐stannylenes: An Experimental and Theoretical Study

Cited by 53 publications

References 57 publications

Transition‐Metal Complexes of Tetrylones [(CO)₅W‐E(PPh₃)₂] and Tetrylenes [(CO)₅W‐NHE] (E=C–Pb): A Theoretical Study

Transition‐Metal Complexes of Tetrylones [(CO)₅W‐E(PPh₃)₂] and Tetrylenes [(CO)₅W‐NHE] (E=C–Pb): A Theoretical Study

Direct estimate of the internal π-donation to the carbene centre within N-heterocyclic carbenes and related molecules

Trapping Molecular SnBr₂(OH)₂ by Tin Alkoxide Coordination: Syntheses and Molecular Structures of [MeN(CH₂CMe₂O)₂SnBr₂]₂·SnBr₂(OH)₂ and RN(CH₂CMe₂O)₂SnL [R = Me, n‐Octyl; L = Lone Pair, Cr(CO)₅, W(CO)₅, Fe(CO)₄, Br₂]

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π‐Bonding in Complexes of Benzannulated Biscarbenes, ‐germylenes, and ‐stannylenes: An Experimental and Theoretical Study

Cited by 53 publications

References 57 publications

Transition‐Metal Complexes of Tetrylones [(CO)5W‐E(PPh3)2] and Tetrylenes [(CO)5W‐NHE] (E=C–Pb): A Theoretical Study

Transition‐Metal Complexes of Tetrylones [(CO)5W‐E(PPh3)2] and Tetrylenes [(CO)5W‐NHE] (E=C–Pb): A Theoretical Study

Direct estimate of the internal π-donation to the carbene centre within N-heterocyclic carbenes and related molecules

Trapping Molecular SnBr2(OH)2 by Tin Alkoxide Coordination: Syntheses and Molecular Structures of [MeN(CH2CMe2O)2SnBr2]2·SnBr2(OH)2 and RN(CH2CMe2O)2SnL [R = Me, n‐Octyl; L = Lone Pair, Cr(CO)5, W(CO)5, Fe(CO)4, Br2]

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Transition‐Metal Complexes of Tetrylones [(CO)₅W‐E(PPh₃)₂] and Tetrylenes [(CO)₅W‐NHE] (E=C–Pb): A Theoretical Study

Transition‐Metal Complexes of Tetrylones [(CO)₅W‐E(PPh₃)₂] and Tetrylenes [(CO)₅W‐NHE] (E=C–Pb): A Theoretical Study

Trapping Molecular SnBr₂(OH)₂ by Tin Alkoxide Coordination: Syntheses and Molecular Structures of [MeN(CH₂CMe₂O)₂SnBr₂]₂·SnBr₂(OH)₂ and RN(CH₂CMe₂O)₂SnL [R = Me, n‐Octyl; L = Lone Pair, Cr(CO)₅, W(CO)₅, Fe(CO)₄, Br₂]