Crystal and molecular structure of the (2,2′-diaminobiphenyl)(R,R-trans-1,2-diaminocyclohexane)platinum(II) complex

Radlowski, Cecilia; Liu, Chui Fan; Jun, Mira

doi:10.1016/s0020-1693(00)82329-4

Cited by 10 publications

(13 citation statements)

References 11 publications

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“…Mechanism of Isomerization. Surprisingly few examples of metal complexes of dabp have been reported, − although it remains a popular component of chiral Schiff base ligands. − Despite a report to the contrary, it is significant that in every case where diastereomers may have been expected upon complexation of dabp, only single isomers were observed. ,, We have recently synthesized [Ru(bipy) 2 (dabp)] 2+ and found only one diastereomer . It is remarkable that a square-planar Pt(II) complex of dabp has been resolved wherein the dabp ligand appears to be the only source of optical activity and that activity is not lost in solution over a period of hours .…”

Section: Discussionmentioning

confidence: 99%

“…With the exception of this latter Pt system, these observations are consistent with the result of the present study that clearly illustrates that atropisomerization of the coordinated dabp ligand is facile for 1 . The observation of one diastereomer could be interpreted as reaction stereospecificity, , but an alternative explanation is that atropisomerization simply permits equilibration to give the thermodynamic diastereomer. It is noteworthy that the atropisomers of the 6,6‘-dimethyl derivative of dabp (dmdabp = 6,6‘-dimethyl-2,2‘-diamino-1,1‘-biphenyl) can be resolved …”

Section: Discussionmentioning

confidence: 99%

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Kinetics and Mechanism of the Stereochemical Isomerization of an Arene−Ruthenium Complex of the Atropisomeric Ligand 1,1‘-Biphenyl-2,2‘-diamine

1999

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(η6-Benzene)(δ/λ-1,1‘-biphenyl-2,2‘-diamine)chlorometal(II) hexafluorophosphate (1; metal = ruthenium, osmium) have been synthesized. The rigid nature of the seven-membered chelate ring formed by the 1,1‘-biphenyl-2,2‘-diamine (dabp) ligand renders the complexes chiral. The resulting C 1 molecular symmetry of 1(M=Ru) that we have observed in the solid state by single-crystal X-ray crystallography is preserved in solution on the NMR time scale. The four N−H protons of 1(M=Ru,Os) are chemically inequivalent in the 1H NMR spectrum at 20 °C. Spin-perturbation NMR experiments in acetone solutions reveal pairwise exchange of the resonances that correspond to the N−H protons on the spin-relaxation time scale. The three mechanisms that would account for such an exchange (atropisomerization of the dabp ligand, inversion of stereochemistry at the metal center, and simultaneous inversion of the stereochemistry at the metal and the ligand) are distinguishable, provided a proper assignment of the four N−H protons can be made in the NMR spectra. Having made that assignment, we conclude from 2D EXSY NMR spectroscopy that the mechanism of exchange is inversion of stereochemistry at the dabp ligand center. This observation contrasts with previous reports that conformational isomers of dabp can be resolved.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Kinetics and Mechanism of the Stereochemical Isomerization of an Arene−Ruthenium Complex of the Atropisomeric Ligand 1,1‘-Biphenyl-2,2‘-diamine

1999

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“…Complexes of the diamine 1,1‘-biphenyl-2,2‘-diamine (DABP, 105 , Figure ) and its derivatives have not yet, to our knowledge, been applied to asymmetric catalysis. Nonetheless, these atropisomeric ligands have attracted a significant amount of attention, − as they are the conformationally dynamic counterparts of the stereochemically fixed DABN and 6,6‘-dimethyl-1,1‘-biphenyl-2,2‘-diamine ( 106 , Figure ), which have proven to be important chiral entities in asymmetric catalysis . As such, we anticipate that DABP and its derivatives also have great potential in enantioselective catalysis.…”

Section: Examination Of the Barrier To Atropisomerization In Biphenyl...mentioning

confidence: 99%

“…The platinum complex [(DABP)Pt(en)] 2+ has been resolved and is stable to racemization at room temperature . The high barrier to atropisomerization necessary for isolation of this complex is surprising, given that, in cases where DABP is bound to chiral metal−ligand combinations, only one diastereomer has been reported. ,− , …”

Section: Examination Of the Barrier To Atropisomerization In Biphenyl...mentioning

confidence: 99%

Use of Achiral and Meso Ligands To Convey Asymmetry in Enantioselective Catalysis

2003

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1. Introduction and Scope 3297 2. The Use of Achiral Salen Ligands in Asymmetric Catalysis 3305 3. Use of Achiral Biphenol-Based Ligands in Asymmetric Catalysis 3308 3.1. Asymmetric Carbonyl−Ene Reaction 3308 3.2. Asymmetric Addition of Methyl Groups to Aldehydes 3309 3.3. Asymmetric Baeyer−Villiger Oxidation 3309 4. Atropisomeric Biphenyl-Based Phosphines and Related Ligands in Asymmetric Catalysis 3310 4.1. Asymmetric Hydrogenation Reactions Using BIPHEP-Derived Ligands 3311 4.2. Asymmetric Diels−Alder and Carbonyl−Ene Reactions with BIPHEP-Derived Ligands 3313 4.3. Interconversion of Diastereomeric Catalysts and Catalyst Precursors Containing BIPHEP Derivatives 3315 4.4. Mechanistic Aspects of Atropisomerization of BIPHEP 3317 4.5. A Potentially Useful New Class of Achiral Diphosphine Ligands (NUPHOS) 3319 4.6. Complexes of a Meso Cyclohexane-Based Diphosphine 3320 4.7. Spontaneous Resolution of an Asymmetric Catalyst Bearing a Bis(phosphole) Ligand 3320 4.8. A Metallocene Catalyst with a Biphenyl Backbone 3322 4.9. Use of Bis(diphenylphosphino)ferrocene and Related Ligands in Asymmetric Catalysis 3323 4.10. Dynamic Resolution of Bis(phospholyl)−Zr Complexes 3325 5. Examination of the Barrier to Atropisomerization in Biphenyl-Based Diamines 3326

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“…2,2Ј-Diaminobiphenyl and 1,2-diaminocyclohexane bind platinum(II) chloride [30] and two molecules of 2,2Ј-diamino-6,6Ј-dimethylbiphenyl bind to rhodium(III) chloride [31] with bite angles for the diamino groups at the metal atom in the 87Ϫ89°range. Several complexes of the 3-aminopyridinium cation coordinated through the amino groups to copper(II) have been reported and provide a useful comparison.…”

Section: [Cu(l1h 2 )Cl 4 ] (4)mentioning

confidence: 99%

The Coordination Chemistry of 3,3′-Diamino-2,2′-bipyridine and Its Dication: Exploring the Role of the Amino Groups by X-ray Crystallography

Rice

Onions

Vidal

et al. 2002

Eur. J. Inorg. Chem.

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The synthesis and structural chemistry of a series of new divalent transition metal complexes of the bis-bidentate ligand 3,3Ј-diamino-2,2Ј-bipyridine (L1) and its dication L1H 2 are described. Ligand L1 reacts with salts of divalent transition metals to afford the (1:1) metal-ligand complexes (2a−2d) as well as the tris complexes (3a−3f). All complexes were fully characterised by spectroscopic methods and the following compounds [Cu(L1)Cl 2 ] 2 (2a), [Cu(L1)(OAc) 2 ] (2b), [Zn(L1) 3 ][OTf] 2 (3a), and [Zn(L1) 3 ][ZnCl 4 ] (3e and 3f) were structurally characterised. Results from single crystal X-ray diffraction measurements indicate that formation of an intramolecular hydrogen bond between the two amino groups allows the ligand to coordinate divalent metal ions through their diimine binding sites. Furthermore, the structure of compound 2a reveals that it crystallises as a dimer in which each copper ion is bound to two pyridine nitrogen atoms and [a]

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Crystal and molecular structure of the (2,2′-diaminobiphenyl)(R,R-trans-1,2-diaminocyclohexane)platinum(II) complex

Cited by 10 publications

References 11 publications

Kinetics and Mechanism of the Stereochemical Isomerization of an Arene−Ruthenium Complex of the Atropisomeric Ligand 1,1‘-Biphenyl-2,2‘-diamine

Kinetics and Mechanism of the Stereochemical Isomerization of an Arene−Ruthenium Complex of the Atropisomeric Ligand 1,1‘-Biphenyl-2,2‘-diamine

Use of Achiral and Meso Ligands To Convey Asymmetry in Enantioselective Catalysis

The Coordination Chemistry of 3,3′-Diamino-2,2′-bipyridine and Its Dication: Exploring the Role of the Amino Groups by X-ray Crystallography

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