<i>J</i>(Si,H) Coupling Constants in Nonclassical Transition‐Metal Silane Complexes

Scherer, Wolfgang; Meixner, Petra; Batke, Kilian; Barquera‐Lozada, José Enrique; Ruhland, Klaus; Fischer, Andreas; Eickerling, Georg; Eichele, Klaus

doi:10.1002/anie.201604001

Cited by 20 publications

(48 citation statements)

References 36 publications

(75 reference statements)

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“…1c The M … Si interaction increases further in (CH 3 )CpMn(CO) 2 (HSiFPh 2 ) (3) 4a,b which displays an electron withdrawing substituent at the silicon atom of the hydrosilane ligand yielding an asymmetric oxidative addition product (ASOAP). 1c,3f A similar scenario can be also observed in case of the early transition metal hydrosilane complexes such as the d 2titanium complexes Cp 2 Ti(PMe 3 )(HSiHPh 2 ) (4) 4c and Cp 2 Ti(PMe 3 )(HSiHPhCl) (5) 5 . The extent of Si-H bond activation increases only insignificantly from 3-5, however, the J(Si,H) spin-spin couplings change drastically from -52 Hz to +23 Hz.…”

Section: Introductionsupporting

confidence: 63%

“…According to Equation 2 the positive sign of the J  (Si,H) contribution (+92 Hz) is due to the nodal plane in the Ti→*(H-Si-Cl)  back bonding orbital (HOMO; Figure 10a In order to get a more comprehensive picture also for the remaining members of the series Cp 2 Ti(PMe 3 )(HSiMe 3-n Cl n ) (n = 0-3) 8a-d we analyzed all coupling contributions from the interactions between their occupied (Si-H) and Ti→*(H-Si-Cl) orbitals with the complete set of virtual orbitals. 5 These contributions are denoted J ,total (Si,H) in the following. We learn from Table 1 that these negative J ,total (Si,H) couplings do not vary significantly with the number of chloro substituents -67 Hz (8a, n=0); -64 Hz (8b, n=1); -64 Hz (8c, n=2) and -65 Hz (8d, n=3).…”

Section: Resultsmentioning

confidence: 99%

“…3e,10a Such interactions would rely on a pronounced (Ti-H)→*(Si-Cl) orbital interaction mechanism which could not be identified. 5,29 We further note that a related trend has been also found in case of the substitution series Cp The final step of our coupling analysis aims at the origin of the decreasing J(Si,H) values in the d 6 manganese complexes (CH 3 )CpMn(CO) 2 (HSiMe 3-n Cl n ) (n =1-3; 9b-d) (Figure 9) with increasing n. Table 1 shows that in case of the electron-rich d 6 complexes also orbital interactions between the bonding (Mn-H) and virtual orbitals need to be considered. This positive coupling contribution is denoted J Mn,H,total (Si,H) in Figure 10b Due to the pronounced covalent character of the Si-H bonds in the d 6 manganese complexes this trend predominates the total J(Si-H) couplings.…”

Section: Resultsmentioning

confidence: 99%

“…Bond critical points and ring critical points are drawn as blue and green filled circles, respectively. The bonded charge concentration (BCC) in the valence shell of charge concentration at silicon of 4 and 5 is specified in e/Å 5 and marked by a red spot and the values of the Ti-Si bond critical points are denoted in e/Å 3 .…”

Section: Introductionmentioning

confidence: 99%

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J(Si,H) Coupling Constants of Activated Si–H Bonds

et al. 2017

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We outline in this combined experimental and theoretical NMR study that sign and magnitude of J(Si,H) coupling constants provide reliable indicators to evaluate the extent of the oxidative addition of Si-H bonds in hydrosilane complexes. In combination with experimental electron density studies and MO analyses a simple structure-property relationship emerges: positive J(Si,H) coupling constants are observed in cases where M → L π-back-donation (M = transition metal; L = hydrosilane ligand) dominates. The corresponding complexes are located close to the terminus of the respective oxidative addition trajectory. In contrast negative J(Si,H) values signal the predominance of significant covalent Si-H interactions and the according complexes reside at an earlier stage of the oxidative addition reaction pathway. Hence, in nonclassical hydrosilane complexes such as CpTi(PMe)(HSiMeCl) (with n = 1-3) the sign of J(Si,H) changes from minus to plus with increasing number of chloro substituents n and maps the rising degree of oxidative addition. Accordingly, the sign and magnitude of J(Si,H) coupling constants can be employed to identify and characterize nonclassical hydrosilane species also in solution. These NMR studies might therefore help to reveal the salient control parameters of the Si-H bond activation process in transition-metal hydrosilane complexes which represent key intermediates for numerous metal-catalyzed Si-H bond activation processes. Furthermore, experimental high-resolution and high-pressure X-ray diffraction studies were undertaken to explore the close relationship between the topology of the electron density displayed by the η(Si-H)M units and their respective J(Si,H) couplings.

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Section: Introductionsupporting

confidence: 63%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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J(Si,H) Coupling Constants of Activated Si–H Bonds

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“…Evaluating the resulting model provides access to key structural properties such as, for example, intermolecular interactions (Desiraju, 2013;Pawlę dzio et al, 2018). Furthermore, charge density investigations provide valuable insights for synthetic chemists (Stalke, 2011;Flierler & Stalke, 2012;Scherer et al, 2015;Stalke, 2016;Scherer et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Comparison of different strategies for modelling hydrogen atoms in charge density analyses

Köhler

Lübben

Krause

et al. 2019

Acta Crystallogr B Struct Sci Cryst Eng Mater

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The quality of various approximation methods for modelling anisotropic displacement parameters (ADPs) for hydrogen atoms was investigated in a comparative study. A multipole refinement was performed against highresolution single crystal X-ray data of 9-diphenylthiophosphoranylanthracene (SPAnH) and 9,10-bis-diphenylthiophosphoranylanthraceneÁtoluene (SPAnPS). Hydrogen-atom parameters and structural properties derived from our collected neutron data sets were compared with those obtained from the SHADE-server, the software APD-Toolkit based on the invariom database, the results from Hirshfeld atom refinement conducted in the OLEX2 GUI (HARt), and the results of anisotropic hydrogen refinement within XD2016. Additionally, a free refinement of H-atom positions against X-ray data was performed with fixed ADPs from various methods. The resulting C-H bond distances were compared with distances from neutron diffraction experiments and the HARt results. Surprisingly, the refinement of anisotropic hydrogen displacement parameters against the X-ray data yielded the smallest deviations from the neutron values. However, the refinement of bond-directed quadrupole parameters turned out to be vital for the quality of the resulting ADPs. In both model structures, SHADE and, to a lesser extent, APD-Toolkit showed problems in dealing with atoms bonded to carbon atoms with refined Gram-Charlier parameters for anharmonic motion. The HARt method yields the most accurate C-H bond distances compared to neutron data results. Unconstrained refinement of hydrogen atom positions using ADPs derived from all other used approximation methods showed that even with well approximated hydrogen ADPs, the resulting distances were still significantly underestimated. research papers Acta Cryst. (2019). B75, 434-441 Christian Kö hler et al. Strategies for modelling hydrogen atoms 435 research papers Acta Cryst. (2019). B75, 434-441 Christian Kö hler et al. Strategies for modelling hydrogen atoms 441

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Is the R₃Si Moiety in Metal–Silyl Complexes a Z ligand? An Answer from the Interaction Energy

Binh

Milovanović

Puertes-Mico

et al. 2017

Chemistry A European J

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The computation of metal-silyl interaction energies indicates the existence of situations in which the silyl group behaves as a Z-type ligand according to the Green method of covalent-bond classification. There is a scale of relative intrinsic silylicity Π, defined as the ratio of the intrinsic silyl-to-triflate interaction energy of a silyltriflate as a reference compound relative to the silyl-to-metal interaction of given complex, that can reveal in a straightforward manner the propensity of SiR groups to behave chemically as metal-bound "silylium" ions, namely, [SiR ] . Emblematic cases, either taken from the Cambridge Structural Database (CSD) or constructed for the purpose of this study, were also investigated from the viewpoints of extended transition-state natural orbitals for chemical valence (ETS-NOCV) and quantum theory of atoms in molecules (QTAIM) analyses. It is shown in the case of POBMUP-which is the iridium 1,3-bis[(di-tert-butylphosphino)oxy]benzene (POCOP) complex isolated by Brookhart et al.-how slight variations of molecular charge and structure can drastically affect the relative intrinsic silylicity of the SiEt group that is weakly bonded to the hydrido-iridium motif.

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J(Si,H) Coupling Constants in Nonclassical Transition‐Metal Silane Complexes

Cited by 20 publications

References 36 publications

J(Si,H) Coupling Constants of Activated Si–H Bonds

J(Si,H) Coupling Constants of Activated Si–H Bonds

Comparison of different strategies for modelling hydrogen atoms in charge density analyses

Is the R₃Si Moiety in Metal–Silyl Complexes a Z ligand? An Answer from the Interaction Energy

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J(Si,H) Coupling Constants in Nonclassical Transition‐Metal Silane Complexes

Cited by 20 publications

References 36 publications

J(Si,H) Coupling Constants of Activated Si–H Bonds

J(Si,H) Coupling Constants of Activated Si–H Bonds

Comparison of different strategies for modelling hydrogen atoms in charge density analyses

Is the R3Si Moiety in Metal–Silyl Complexes a Z ligand? An Answer from the Interaction Energy

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Is the R₃Si Moiety in Metal–Silyl Complexes a Z ligand? An Answer from the Interaction Energy