scholarly journals Chiral, Heterometallic Lanthanide–Transition Metal Complexes by Design

Inorganics ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 72 ◽  
Author(s):  
Anders Øwre ◽  
Morten Vinum ◽  
Michal Kern ◽  
Joris van Slageren ◽  
Jesper Bendix ◽  
...  
Keyword(s):  
Transition Metal ◽  
Transition Metal Complexes ◽  
Lewis Acids ◽  
Antiferromagnetic Coupling ◽  
Relaxation Processes ◽  
Coordination Geometry ◽  
Ferromagnetic Coupling ◽  
Metal Acetylacetonates ◽  
Metal Centers ◽  
Tunneling Pathways

Achieving control over coordination geometries in lanthanide complexes remains a challenge to the coordination chemist. This is particularly the case in the field of molecule-based magnetism, where barriers for magnetic relaxation processes as well as tunneling pathways are strongly influenced by the lanthanide coordination geometry. Addressing the challenge of design of 4f-element coordination environments, the ubiquitous Ln(hfac)3 moieties have been shown to be applicable as Lewis acids coordinating transition metal acetylacetonates facially leading to simple, chiral lanthanide–transition metal heterodinuclear complexes. The broad scope of this approach is illustrated by the synthesis of a range of such complexes LnM: LnM(hfac)3(μ2-acac-O,O,O′)3 (Ln = La, Pr, Gd; M = Cr, Fe, Ga), with approximate three-fold symmetry. The complexes have been crystallographically characterized and exhibit polymorphism for some combinations of 4f and 3d metal centers. However, an isostructural set of systems spanning several lanthanides which exhibit spontaneous resolution in the orthorhombic Sohncke space group P212121 is presented here. The electronic structure and ensuing magnetic properties have been studied by EPR spectroscopy and magnetometry. The GdFe, PrFe, and PrCr complexes exhibit ferromagnetic coupling, while GdCr exhibits antiferromagnetic coupling. GdGa exhibits slow relaxation of the magnetization in applied static fields.

Übergangsmetallkomplexe mit Schwefelliganden, LXXVI Redox- und Additionsreaktionen von Nickelkomplexen mehrzähniger Thioether-Thiolat-Liganden. Röntgenstrukturanalysen von (NMe4)2[Ni(′S2′)2] und [Ni(′S4 – C3′)(PMe3)] / Transition Metal Complexes with Sulfur Ligands, LXXVI Redox and Addition Reactions of Nickel Complexes with Multidentate Thioether-Thiolato Ligands. X-Ray Structure Determinations of (NMe4)2[Ni(′S2′)2] and [Ni(′S4–C3′)(PMe3)]

1991 ◽  
Vol 46 (12) ◽  
pp. 1601-1608 ◽  
Author(s):  
Dieter Sellmann ◽  
Stefan Fünfgelder ◽  
Falk Knoch ◽  
Matthias Moll
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Structure Analysis ◽  
Transition Metal Complexes ◽  
Nickel Complexes ◽  
Addition Reactions ◽  
Coordination Geometry ◽  
X Ray ◽  
Square Planar ◽  
Structure Determinations

In order to elucidate specific properties of nickel sulfur complexes, redox and addition-elimination reactions of [Ni(′OS4')]2, [Ni(′NHS4')]2, [Ni(′S5')], [Ni('S4—C5')], and [Ni('S4—C3')] were investigated ('OS4′ 2' = 2,2'-bis(2-mercaptophenylthio)diethylether(2—), 'NHS4'2- = 2,2'-bis(2-mercaptophenylthio)diethylamine(2—), 'S5'2- = 2,2'-bis(2-mercaptophenylthio)diethylsulfide(2—), 'S4-C5'2- = 1,5-bis(2-mercaptophenylthio)pentane(2—), 'S4—C3'2- = 1,3-bis(2-mercaptophenylthio)propane(2—)).Cyclovoltammetry proves the complexes to be redox inactive between —1.4 and +0.8 V vs. NHE. Above +0.8 V the complexes are irreversibly oxidized, below —1,4 V desalkylation takes place and [Ni(′S,′)2]2- is formed. An X-ray structure analysis was carried out of (NMe4)2[Ni(′S2')2], which shows a planar anion with the Ni center in a nearly perfect square planar coordination. Distances and angles are practically identical to those in the [Ni(′S2')2-] monoanion.The complexes coordinate only phosphines as coligands, but thioether donors simultaneously decoordinate and, dependant of reaction temperature, mono- or trisphosphine complexes are formed. [Ni(′S4—C3')(PMe3)] was characterized by X-ray structure analysis and exhibits a square pyramidal coordination geometry.

Cooperative Catalysis of Combined Systems of Transition-Metal Complexes with Lewis Acids: Theoretical Understanding

2016 ◽  
Vol 16 (5) ◽  
pp. 2405-2425 ◽  
Author(s):  
Wei Guan ◽  
Guixiang Zeng ◽  
Hajime Kameo ◽  
Yoshiaki Nakao ◽  
Shigeyoshi Sakaki
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Lewis Acids ◽  
Theoretical Understanding ◽  
Cooperative Catalysis

Übergangsmetallkomplexe mit Schwefelliganden, LXV. Diastereospezifische Alkylierung von [Mo(NO)2(′S2′)2]2- zu chiralen [Mo(NO)2(′RS4')]-Komplexen mit chirotopen und prostereogenen Mo-Zentren / Transition Metal Complexes with Sulfur Ligands, LXV. Diastereospecific Alkylation of [Mo(NO)2(′S2')2]2- to Chiral [Mo(NO)2(′RS4')] Complexes with Chirotopic and Prostereogenic Mo-Centers

1991 ◽  
Vol 46 (10) ◽  
pp. 1343-1348 ◽  
Author(s):  
Dieter Sellmann ◽  
Franz Grasser ◽  
Falk Knoch ◽  
Matthias Moll
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Parent Compound ◽  
Metal Center ◽  
Chiral Complexes ◽  
Metal Centers ◽  
Electronic Character

In order to investigate how chirotopicity and stereogenicity of metal centers influence the enantioselectivity of metal centered reactions the stereogenic properties of metal centers in chiral complexes have to be varied without changing their electronic character. Diastereospecific alkylation of [Mo(NO)2(′S2′ )2]2- by racemic 1,2-dibromopropane and 1,2-dibromobutane yields the title complexes [Mo(NO)2(′MeS4′ )] and [Mo(NO)2(′EtS4′)] that differ from the parent compound [Mo(NO)2('S4′)] with respect to the stereogenicity of the metal center and allow future investigations of the question raised above.

Übergangsmetallkomplexe mit Schwefelliganden, XXXII*: Synthese der sterisch anspruchsvollen Thiolat-amin-Liganden tbu2-ma-H = 2-Mercapto-3,5-di-tbutylanilin und tbu4-bmae-H2 = 1,2-Bis(2-mercapto-3,5-di-tbutylaniIino)ethan sowie ihrer Eisen-, Ruthenium- und Zink-Komplexe [Fe(CO)2(tbu2-ma)2], [Zn(tbu2-ma)2] und [RuL2(tbu4-bmae)], L = CO, PMe3, PPh3/ Transition Metal Complexes with Sulfur Ligands, XXXII*: Synthesis of the Sterically Demanding New Thiolate-amine Ligands tbu2-ma-H = 2-Mercapto-3,5-di-tbutylanilin und tbu4-bmae-H2 = 1,2-Bis(2-mercapto-3,5-di-tbutylaniIino)ethane as well as of their Iron-, Ruthenium- and Zinc Complexes [Fe(CO)2(tbu2-ma)2], [Zn(tbu2-ma)2] and [RuL2(tbu4-bmae)], L = CO, PMe3, PPh3

1987 ◽  
Vol 42 (10) ◽  
pp. 1291-1297 ◽  
Author(s):  
Dieter Sellmann ◽  
Olaf Käppler
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Acid Hydrolysis ◽  
Organic Solvents ◽  
Transition Metal Complexes ◽  
Zinc Complexes ◽  
Metal Centers ◽  
Sterically Demanding ◽  
Amine Ligands ◽  
Soluble Complexes

Abstract In order to obtain soluble complexes containing sterically protected metal centers the new bi- and tetradentate thiolate amine ligands 2-mercapto-3,5-di-tbutylaniline (= tbu2-ma-H) and 1,2-bis(2-mercapto-3,5-di-tbutylanilino)ethane (= tbu4-mae-H2) were synthesized. tbu2-ma-H reacts with FeCl2-4 H2O and CO to give [Fe(CO)2(tbu2-ma)2], with Zn(ac)2 -2 H2O [Zn(tbu2-ma)2] is obtained whose acid hydrolysis and reaction with H2S, respectively, yield pure tbu2-Ina-H. The condensation of tbu2-ma-H with glyoxal yields the respective bis-benzthiazolidine, which is re­duced by LiAlH4 in the presence of Na[N(SiMe3)2] to tbu4-bmae-H2. tbu4-bmae-Li2. reacts with [Ru(CO)3(THF)Cl2], [Ru(PMe3)4Cl2] and [Ru(PPh3)2(CH3CN)2Cl2], respectively, to yield [Ru(L)2(Tm4-bmae)j (L = CO, PMe3, PPh3). The complexes are more soluble in organic solvents than the corresponding unsubstituted bmae complexes, bmae2- = 1,2-bis(2-mercaptoanilino)- ethane(2-).

Darstellung und Kristallstrukturen einiger Übergangsmetall-Komplexverbindungen mit Liganden mit dem 4,5-Benzo-3-methyl-1,3,2-oxazaphosphorinan-6-on-Gerüst / Synthesis and X-Ray Crystal Structures of Some Transition-Metal Complexes Involving Ligands with the 4,5-Benzo-3-methyl-1,3,2-oxazaphosphorinan-6-one Framework

1994 ◽  
Vol 49 (11) ◽  
pp. 1481-1493 ◽  
Author(s):  
Axel Fischer ◽  
Ion Neda ◽  
Peter G. Jones ◽  
Reinhard Schmutzler
Keyword(s):  
Transition Metal ◽  
Single Crystal ◽  
Transition Metal Complexes ◽  
Nmr Spectra ◽  
Coordination Geometry ◽  
X Ray ◽  
Distorted Octahedral Coordination ◽  
Envelope Conformation ◽  
Square Planar ◽  
Distorted Octahedral

4,5-Benzo-2-diethylamino-3-methyl-1,3,2-oxazaphosphorinan-6-one 1 and 4,5-benzo-2-[bis- (2-chlorethyl)amino]-3-methyl-1,3,2-oxazaphosphorinan-6-one 3 reacted with dichloro- (cycloocta-1,5-diene)platinum(II) [(COD)PtCl2] to give the ds-dichloro-platinum(II) com­plexes 2 and 4, respectively. The reaction of 1 with tricarbonyl(cycloheptatriene)molybdenum(0) led to a mixture of isomers including fac-tris-(4,5-benzo-2-diethylamino-3-methyl- 1,3,2-oxazaphosphorinan-6-one)tricarbonylmolybdenum(0) 5. The reaction of 4,5-benzo- 2-acetylamino-3-methyl-1,3,2-oxazaphosphorinan-6-one 6 with dichloro(cycloocta-1,5-diene)- platinum(II) furnished the cis-complex 7. 4,5-Benzo-2-fluoro-3-methyl-1,3,2-oxazaphosphorinan-6-one 8 reacted with both tetracarbonyl(norbornadiene)molybdenum(0) and dichloro- (cycloocta-1,5-diene)platinum(II) to form the cis-complexes 9 and 10. 31P-31P coupling con­stants from the 31P NMR spectra for the complexes 2, 4 and 9 are reported. The structures of 5, 7, 9 and 10 were established by single crystal X-ray analysis. All ligands coordinate via phosphorus only. The structure of 5 shows strongly distorted octahedral coordination geome­try associated with the presence of three bulky ligands. The Mo-P bond lengths in 5 are, for the same reason, significantly longer than in 9. The heterocycles of the ligands in 5 do not show the expected envelope conformation but are almost planar. The platinum(II) complex 7 shows crystallographic C2-symmetry, the coordination geometry at platinum being almost ideally square-planar. The same coordination geometry is observed for 10, the ligands of which possess the expected envelope conformation with phosphorus out of the plane.

α-Pyridinyl Alcohols, α,α’-Pyridine Diols, α-Bipyridinyl Alcohols, and α,α’-Bipyridine Diols as Structure Motifs Towards Important Organic Molecules and Transition Metal Complexes

2020 ◽  
Vol 17 (5) ◽  
pp. 344-366
Author(s):  
Tegene T. Tole ◽  
Johannes H.L. Jordaan ◽  
Hermanus C.M. Vosloo
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Single Molecule ◽  
Organic Molecules ◽  
Metal Cluster ◽  
Metal Center ◽  
Phosphine Ligands ◽  
High Ability ◽  
Metal Centers

Background: The preparation and use of pyridinyl alcohols as ligands showed incredible increment in the past three decades. Important property of pyridinyl alcoholato ligands is their strong basicity, which is mainly due to the lack of resonance stabilization of the corresponding anion. This strongly basic anionic nature gives them high ability to make bridges between metal centers rather than to bind to only one metal center in a terminal fashion. They are needed as ligands due to their ability to interact with transition metals both covalently (with oxygen) and hemilabile coordination (through nitrogen). Objective: The review focuses on the wide application of α-pyridinyl alcohols, α,α’-pyridine diols, α- bipyridinyl alcohols, and α,α’-bipyridine diols as structure motifs in the preparation of important organic molecules which is due to their strongly basic anionic nature. Conclusion: It is clear from the review that in addition to their synthetic utility in the homogeneous and asymmetric catalytic reactions, the preparation of the crown ethers, cyclic and acyclic ethers, coordinated borates (boronic esters), pyridinyl-phosphine ligands, pyridinyl-phosphite ligands, and pyridinyl-phosphinite ligands is the other broad area of application of pyridinyl alcohols. In addition to the aforementioned applications they are used for modeling mode of action of enzymes and some therapeutic agents. Their strongly basic anionic nature gives them high ability to make bridges between metal centers rather than to bind to only one metal center in a terminal fashion in the synthesis of transition metal cluster complexes. Not least numbers of single molecule magnets that can be used as storage of high density information were the result of transition metal complexes of pyridinyl alcoholato ligands.

scholarly journals Coordination Behavior of [Cp″2Zr(µ1:1-As4)] towards Lewis Acids

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2966
Author(s):  
Veronika Heinl ◽  
Gábor Balázs ◽  
Sarah Koschabek ◽  
Maria Eckhardt ◽  
Martin Piesch ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Lewis Acid ◽  
Reaction Temperature ◽  
Lewis Acids ◽  
Computational Studies ◽  
Coordination Modes ◽  
Coordination Numbers ◽  
Coordination Behavior

The functionalization of the arsenic transfer reagent [Cp″2Zr(η1:1-As4)] (1) focuses on modifying its properties and enabling a broader scope of reactivity. The coordination behavior of 1 towards different Lewis-acidic transition metal complexes and main group compounds is investigated by experimental and computational studies. Depending on the steric requirements of the Lewis acids and the reaction temperature, a variety of new complexes with different coordination modes and coordination numbers could be synthesized. Depending on the Lewis acid (LA) used, a mono-substitution in [Cp″2Zr(µ,η1:1:1:1-As4)(LA)] (LA = Fe(CO)4 (4); B(C6F5)3 (7)) and [Cp″2Zr(µ,η3:1:1-As4)(Fe(CO)3)] (5) or a di-substitution [Cp″2Zr(µ3,η1:1:1:1-As4)(LA)2] (LA = W(CO)5 (2); CpMn(CO)2 (3); AlR3 (6, R = Me, Et, iBu)) are monitored. In contrast to other coordination products, 5 shows an η3 coordination in which the butterfly As4 ligand is rearranged to a cyclo-As4 ligand. The reported complexes are rationalized in terms of inverse coordination.

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