scholarly journals Studies towards the Synthesis of a Heterobimetallic Zirconium Germanium Complex from Imidozirconocenes, Germanimines and Germylenes

2021 ◽  
Author(s):  
◽  
Peter Chapple
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Bond Cleavage ◽  
Lone Pair ◽  
Molecular Orbital Calculations ◽  
Late Transition Metal ◽  
Zirconium Complexes ◽  
Wide Range ◽  
Late Transition ◽  
Nitrogen Bond

<p>Early-late transition metal heterobimetallic complexes with direct metal to metal interactions are desirable synthetic targets due to the complementary reactivity of the two different metals present in these compounds. The electron-rich late transition metal (often Rh, Ir, Fe, or Mo), and electron-poor early transition metal create an ideal environment for heterolytic bond cleavage in what is often termed ‘cooperative reactivity’. This project aimed to synthesise a zirconium-germanium heterobimetallic complex based on a known heterobimetallic ligand scaffold; 1.   The synthesis of the desired heterobimetallic 1 was attempted using two different synthetic approaches. The first involved the investigating the reactivity between an unsaturated zirconium nitrogen bond (an imidozirconocene) and a germanium(II) source with a lone pair of electrons (known as a germylene). The second approach investigated the reactivity between an unsaturated germanium nitrogen bond (a germanimine) and a zirconium(II) source. In order to have the highest chance of success, a wide range of germanium and zirconium complexes were synthesised.  The novel germylenes include [Ge(NAPHTMS)] (NAPHTMS = [1,8-((CH3)3Si)N)2C10H6]) and [Ge(BIANMes)] (BIANMes = [((2,4,6-Me(C6H2)N)2)C12H6)]). These proved to be unreactive towards the imidozirconium species [Cp2Zr(NAr*)(THF)] and [Cp2Zr(NDipp)(THF)] (Ar* = (2,6-(C6H5)2CH)-4-(tBu)C6H2), Dipp = (2,6-((CH3)2CH)C6H3)) as well as other amidozirconocenes. However, within these studies, the mixed coordination germanium species [[Ge(NAPHTMS)Ge(Bu)(NAPHTMS)]-[Li(THF4)]+] and [[Ge(NAPHTMS)Ge(Me)(NAPHTMS)]-[Li(THF4)]+]were synthesised. Density functional theory (DFT) molecular orbital calculations were used to help explain the observed reactivity.  With regards to the second approach, routes to new germanimine complexes such as [(HMDS)2Ge(NMes)] ((HMDS) = ((CH3)3Si)2N), Mes = (2,4,6-CH3(C6H3))), were explored, and several methods for generating “Cp2Zr” were examined. Although these conditions proved unsuccessful for generating 1, the reaction between dialkyl zirconocene with azides to form novel zirconocene triazenido complexes was discovered and the sterics affecting the synthesis of new germanimine complexes was investigated.</p>

scholarly journals Studies towards the Synthesis of a Heterobimetallic Zirconium Germanium Complex from Imidozirconocenes, Germanimines and Germylenes

2021 ◽  
Author(s):  
◽  
Peter Chapple
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Bond Cleavage ◽  
Lone Pair ◽  
Molecular Orbital Calculations ◽  
Late Transition Metal ◽  
Zirconium Complexes ◽  
Wide Range ◽  
Late Transition ◽  
Nitrogen Bond

<p>Early-late transition metal heterobimetallic complexes with direct metal to metal interactions are desirable synthetic targets due to the complementary reactivity of the two different metals present in these compounds. The electron-rich late transition metal (often Rh, Ir, Fe, or Mo), and electron-poor early transition metal create an ideal environment for heterolytic bond cleavage in what is often termed ‘cooperative reactivity’. This project aimed to synthesise a zirconium-germanium heterobimetallic complex based on a known heterobimetallic ligand scaffold; 1.   The synthesis of the desired heterobimetallic 1 was attempted using two different synthetic approaches. The first involved the investigating the reactivity between an unsaturated zirconium nitrogen bond (an imidozirconocene) and a germanium(II) source with a lone pair of electrons (known as a germylene). The second approach investigated the reactivity between an unsaturated germanium nitrogen bond (a germanimine) and a zirconium(II) source. In order to have the highest chance of success, a wide range of germanium and zirconium complexes were synthesised.  The novel germylenes include [Ge(NAPHTMS)] (NAPHTMS = [1,8-((CH3)3Si)N)2C10H6]) and [Ge(BIANMes)] (BIANMes = [((2,4,6-Me(C6H2)N)2)C12H6)]). These proved to be unreactive towards the imidozirconium species [Cp2Zr(NAr*)(THF)] and [Cp2Zr(NDipp)(THF)] (Ar* = (2,6-(C6H5)2CH)-4-(tBu)C6H2), Dipp = (2,6-((CH3)2CH)C6H3)) as well as other amidozirconocenes. However, within these studies, the mixed coordination germanium species [[Ge(NAPHTMS)Ge(Bu)(NAPHTMS)]-[Li(THF4)]+] and [[Ge(NAPHTMS)Ge(Me)(NAPHTMS)]-[Li(THF4)]+]were synthesised. Density functional theory (DFT) molecular orbital calculations were used to help explain the observed reactivity.  With regards to the second approach, routes to new germanimine complexes such as [(HMDS)2Ge(NMes)] ((HMDS) = ((CH3)3Si)2N), Mes = (2,4,6-CH3(C6H3))), were explored, and several methods for generating “Cp2Zr” were examined. Although these conditions proved unsuccessful for generating 1, the reaction between dialkyl zirconocene with azides to form novel zirconocene triazenido complexes was discovered and the sterics affecting the synthesis of new germanimine complexes was investigated.</p>

Condensed [OPr4]10+ and Discrete [AsO3]3–Ψ1-Tetrahedra in Pr5O4Cl[AsO3]2

2010 ◽  
Vol 65 (5) ◽  
pp. 549-555 ◽  
Author(s):  
Hamdi Ben Yahia ◽  
Antoine Villesuzanne ◽  
Ute Ch. Rodewald ◽  
Thomas Schleid ◽  
Rainer Pöttgen
Keyword(s):  
Density Functional Theory ◽  
Spatial Distribution ◽  
Transition Metal ◽  
Density Functional ◽  
Lone Pair ◽  
Late Transition Metal ◽  
Energy Bands ◽  
Functional Theory ◽  
Late Transition ◽  
Pair Energy

The oxide chloride arsenite Pr5O4Cl[AsO3]2 was obtained as green crystals as a by-product of the synthesis of PrOTAs oxide arsenides (T = late transition metal), starting from Pr6O11, a transition metal oxide, arsenic, and an NaCl/KCl flux. Pr5O4Cl[AsO3]2 crystallizes with the monoclinic Nd5O4Cl[AsO3]2-type structure, space group C2/m. The structure was refined from single-crystal diffractometer data: a = 12.4943(15), b = 5.6884(13) c = 9.0776(19) Å , β = 116.61(1)°, R(F) = 0.0264, wR(F2) = 0.0509, 542 F2 values, and 52 variables. It is built up from corrugated layers of edge- and corner-sharing [OPr4]10+ tetrahedra, which are connected via chloride anions. The space between the layers is filled by these Cl− and discrete arsenite anions [AsO3]3− with lone pairs pointing towards each other. The network of condensed [OPr4]10+ tetrahedra is compared with the different arrays in the oxide pnictides α-PrOZnP, and in β -PrOZnP. Arsenic lone pair energy bands, main interactions, and the spatial distribution were identified precisely using density functional theory (DFT). Among the three crystallographically different sites for praseodymium, one was found non-magnetic in these calculations.

Factors Promoting Alkene Migratory Insertion into Metal-Nitrogen Bond during Hydroamination in Recent Studies

2021 ◽  
Vol 18 ◽  
Author(s):  
Wenlai Han
Keyword(s):  
Transition Metal ◽  
Late Transition Metal ◽  
Electronic Effects ◽  
Metal Centers ◽  
Unsaturated Bond ◽  
Factors Influencing ◽  
Migratory Insertion ◽  
Late Transition ◽  
Metal Catalyzed ◽  
Nitrogen Bond

: Migratory insertion is a fundamental organometallic transformation that enables the functionalization of an unsaturated bond. Recent reports on catalytic hydroamination provide evidence that supports an intermolecular migratory insertion pathway featuring alkene insertion into metal-nitrogen (M-N) bonds. This article presents factors influencing the rate of migratory insertion in late-transition metal-catalyzed hydroamination, including steric and electronic effects from ligands, alkenes, and metal centers, along with stabilization from coordinated amine intermediates and ordered transition states.

Hydrosilylation as an efficient tool for polymer synthesis and modification with methacrylates

RSC Advances ◽  
2015 ◽  
Vol 5 (8) ◽  
pp. 5879-5885 ◽  
Author(s):  
Nuttapol Risangud ◽  
Zhijian Li ◽  
Athina Anastasaki ◽  
Paul Wilson ◽  
Kristian Kempe ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Polymer Synthesis ◽  
Late Transition Metal ◽  
Efficient Tool ◽  
Silicon Compounds ◽  
Late Transition

Hydrosilylation is a well-established reaction for the preparation of organo-silicon compounds, in which vinyl groups react with silanes (Si–H) usually catalysed by late transition metal complexes, most often Pt(ii) complexes.

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