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.

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.

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-).

Übergangsmetallkomplexe mit Schwefelliganden, XXIV* Reduktive Nitrosylierung von [MoCl2(dttd)] zu [Mo(NO)2(dttd)];Eigenschaften, Struktur und Reaktion zu NPR3-Komplexen[Mo(NO)(NPR3)dttd] (PR3=PMe3, PEt3, PMePh2, PEtPh2, PPh3;dttd2-=2,3,8,9-Dibenzo-1,4,7,10-tetrahiadecan(2-)) / Transition Metal Complexes with Sulfur Ligands, XXIV*Reductive Nitrosylation of [MoCl2(dttd)] to [Mo(NO)2(dttd); Properties, Structure an Reaction to NPR3 Complexes [Mo(NO)(NPR3)dttd] (PR3=PMe3, PEt3, PMePh2, PEtPh2, PPh3; dttd2-=2,3,8,9-dibenzo-1,4,7,10-tetrahiadecane (2-))

1986 ◽  
Vol 41 (12) ◽  
pp. 1551-1560 ◽  
Author(s):  
Dieter Sellmann ◽  
Johannes Keller ◽  
Matthias Moll ◽  
Horst Philipp Beck ◽  
Wolfgang Milius
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Structure Analysis ◽  
Transition Metal Complexes ◽  
Reaction Mechanisms ◽  
Metal Centers ◽  
X Ray ◽  
Reductive Nitrosylation ◽  
Reactions With Nucleophiles ◽  
Normal Bond

AbstractIn order to study the properties of sulfur coordinated transition metal centers. [MoCl2dttd] (dttd2 = 2,3,8,9-dibenzo-1,4.7,10-tetrathiadecane(2-)) was reacted with NO in the presence of Zn. [Mo(NO)2dttd] was obtained whose X-ray structure analysis shows that Mo is coordinated pseudo-octahedrally by two trans thiolato S, two cis thioether S as well as two cis N atoms of nearly linear MoNO groups. With respect to its low v(NO) frequencies (1760/1665 cm -1) and quite normal bond lengths as well as angles [Mo(NO)2dttd] shows unexpectedly facile and rapid reactions with nucleophiles; with two equivalents of PR3 (PMe3, PEt3, PMePh2, PEtPh2, PPh3) it yields the corresponding phosphiniminato complexes [Mo(NO)(NPR3)dttd] and free phosphinoxides OPR3, respectively. Reaction mechanisms as well as the bonding situation in the [Mo(NPR3)] entity are discussed; on the basis of 95Mo and 14N NMR it is concluded that the conversion of NO into NPR3 ligands includes a reduction of N(+2) to N(-3) as well as an oxidation of (formal) Mo(+2) to Mo(+3). With H2O the [Mo(NO)(NPR3)dttd] complexes hydro­lyze with loss of the NPR3 ligands and formation of binuclear [Mo(NO)dttd]2. The ease of hydrolysis depends on the substituents R: In THF [Mo(NO)(NPMe3)dttd] hydrolyzes at 20 °C within a few minutes, [Mo(NO)(NPPh3)dttd], however, needs the addition of cone. HCl.

Transition-Metal Complexes with Pyrazolyl Bridging Ligands between Very Different Metal Centers

1980 ◽  
Vol 19 (11) ◽  
pp. 931-932 ◽  
Author(s):  
Stephen R. Stobart ◽  
Keith R. Dixon ◽  
Donald T. Eadie ◽  
Jerry L. Atwood ◽  
Michael D. Zaworotko
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Bridging Ligands ◽  
Metal Centers
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