Ein vereinheitlichendes Bindungskonzept für Metall‐Hydrosilankomplexe

Scherer, Wolfgang; Meixner, Petra; Barquera‐Lozada, José Enrique; Hauf, Chrıstoph; Obenhuber, Andreas; Brück, Andreas; Wolstenholme, David J.; Ruhland, Klaus; Leusser, Dirk

doi:10.1002/ange.201210224

Cited by 13 publications

(3 citation statements)

References 37 publications

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“…This finding is further in line with the pronounced broadening of the isolated ν is (C–H br ) stretching modes in the infrared studies. In case of agostic interactions and the related σ silane complexes, we have shown that the presence of local Lewis acidic sites at the transition metal center M provides a necessary prerequisite for the establishment of covalent M ··· H br –C interactions. This is actually also the case for the Pt ··· H br –C interactions in 2 , 2a , 3 and 4 .…”

Section: Methodsmentioning

confidence: 97%

Pressure‐Enhanced C–H Bond Activation in Chloromethane Platinum(II) Complexes

et al. 2019

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The nature of the interaction between chloromethanes CH 4-n Cl n and Pt(II) complexes has been studied by highpressure X-ray diffraction and infrared spectroscopy in combination with DFT calculations. In case of electron rich complexes such as d 8 -Pt(btz-N,N′)(phenyl)L with L = phenyl, Cl, Br and btz = 2,2′-Bi-5,6-dihydro-4H-1,3-thiazine stable chloroform adducts with bridging hydrogen atoms in the η 1 (C-H)Pt moieties were isolated which display highly activated C-H bonds. This activa-The activation of carbon-hydrogen bonds is usually hampered by their rather apolar covalent character and large bond dissociation energies. For example the C-H bond dissociation enthalpies in simple alkanes such as methane [DH 298 = 439.28(13) kJ mol -1 ] are virtually as large as in the H 2 molecule [DH 298 = 435.998(13) kJ mol -1 ] displaying the prototype of a strong covalent bond. [1] As a consequence, alkanes are neither good electron donors nor good acceptors since the σ(C-H) bonding orbital is low in energy while the antibonding σ*(C-H) orbital is high lying. Hence, C-H bonds are generally considered to be chemically rather inert and their selective activation remains a challenge in organometallic chemistry. [2][3][4] This obstacle can be overcome by metal-assisted C-H bond activation in cases where an alkane ligand coordinates either end-on (η 1 ) or side-on (η 2 ) to a metal-ligand fragment ML n (Scheme 1). [5,6] In case of electron-rich late transition metal complexes two bonding scenarios with short M···H br -C contacts are usually observed for methane and halomethane d 8 -Pt complexes, where H br denotes a bridging hydrogen atom. These are illustrated in case of the theoretical model systems (CH 3 ) 2 Pt(NH 3 )(CH 4 ) 1a and (CH 3 ) 2 Pt(NH 3 ) 2 ·(CHCl 3 ) 1b in Scheme 1. We note, that all DFT calculations were performed with ADF using the BP86 functional, the ZORA for the descrip- [a]

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Section: Methodsmentioning

confidence: 97%

Pressure‐Enhanced C–H Bond Activation in Chloromethane Platinum(II) Complexes

et al. 2019

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“…that describes the charge‐density transfer operated variably by the hydrido ligand is another formulation of our conclusion. It is believed that the unifying bonding concept proposed by Scherer et al., which has been tested on a limited number of cases to date, could constitute solid grounds for understanding the structure–reactivity factors that influence bonding within the M‐H‐Si motif. From our viewpoint, understanding the factors that cause high silylicity and its collapse is of utmost importance for the design of new catalysts.…”

Section: Resultsmentioning

confidence: 99%

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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“…In the region close to the carbon atoms bonded to Pt, there are two ELI‐D Pt–C bonding basins [V(Pt–C), Figure ] that have an electronic population around 1.5 e. These two high‐electron‐localization regions point toward two low‐localization sectors in the vicinity of the metal. In the analysis of the topology of ▽ 2 ϱ ( r ), similar regions around the metal had been associated with Lewis acidic sites . Again, the reduction of the size of terminal groups does not generate a significant change in the electronic populations of V(Pt–C) in case of the symmetric tautomers.…”

Section: Resultsmentioning

confidence: 99%

The Role of Bulkiness in Haptotropic Shifts of Metal–Cumulene Complexes

2016

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In metal–cumulene complexes, the metal easily slides through the double bonds of the chain. A series of late‐transition‐metal–[5]cumulene complexes has been studied by theoretical and experimental methods in order to understand the factors that control such haptotropic shifts. The bulkiness of the cumulene terminal groups plays a central role in the tautomeric preferences. The quantum theory of atoms in molecules and the electron localizability indicator show that the M–C bond closer to the terminal groups is significantly weakened by steric interactions between these groups and the rest of ligands around the metal center. The results emphasize that special attention should be paid to the orientation of both the bulky substituents at the cumulene and other voluminous ligands around the metal, because the orientation of such moieties is important in predicting the direction of the haptotropic equilibrium correctly.

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Ein vereinheitlichendes Bindungskonzept für Metall‐Hydrosilankomplexe

Cited by 13 publications

References 37 publications

Pressure‐Enhanced C–H Bond Activation in Chloromethane Platinum(II) Complexes

Pressure‐Enhanced C–H Bond Activation in Chloromethane Platinum(II) Complexes

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

The Role of Bulkiness in Haptotropic Shifts of Metal–Cumulene Complexes

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Ein vereinheitlichendes Bindungskonzept für Metall‐Hydrosilankomplexe

Cited by 13 publications

References 37 publications

Pressure‐Enhanced C–H Bond Activation in Chloromethane Platinum(II) Complexes

Pressure‐Enhanced C–H Bond Activation in Chloromethane Platinum(II) Complexes

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

The Role of Bulkiness in Haptotropic Shifts of Metal–Cumulene Complexes

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