Conformational behaviour of bridging diphenylphosphido ligands

Barker, John J.; Orpen, A. Guy

doi:10.1107/s0108768198014177

Acta Crystallogr Sect B

1999

DOI: 10.1107/s0108768198014177

|View full text |Cite

Conformational behaviour of bridging diphenylphosphido ligands

John J. Barker

A. Guy Orpen

Abstract: Data retrieved from the Cambridge Structural Database for crystal structures containing (µ-diphenylphosphido) metal complexes, [M(2){µ-PPh(2)}] (where M is a d-block element), have been analysed to evaluate the conformational behaviour of these species. The observed distribution of torsion angles about the P-C bonds has been compared with the potential energy surface (PES) for phenyl rotations in a representative species [(AuBr)(2){µ-PPh(2)}](-) computed using the universal force field. Good agreement was obta… Show more

Help me understand this report

Search citation statements

Order By: Relevance

Paper Sections

Select...

Citation Types

Supporting

Mentioning

Contrasting

Year Published

2000

2009

Publication Types

Select...

Article3

Relationship

Self Cite2

Independent1

Authors

Journals

Cited by 3 publications

(1 citation statement)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…• Typical molecular dimensions 2 • Molecular flexibility of metal complexes 3 • Reaction pathways in metal cluster complexes 4 • Bonding in metal phosphine complexes 4 • Conformational analysis in metal phosphines 5 • Intermolecular bonding:…”

mentioning

confidence: 99%

Recognition of spatial motifs in protein structures

Madsen¹,

Kleywegt²

2000

Acta Cryst Sect A

View full text Add to dashboard Cite

There are now over 200,000 structures in the Cambridge Structural Database (CSD) 1 of which ca. 60% are of molecular inorganic species. As such the CSD is an unrivalled source on information on intramolecular and intermolecular geometry in this aspect of chemistry.Areas of molecular inorganic chemistry to which the CSD have been usefully applied include the following:• Typical molecular dimensions

show abstract

mentioning

confidence: 99%

Recognition of spatial motifs in protein structures

Madsen¹,

Kleywegt²

2000

Acta Cryst Sect A

View full text Add to dashboard Cite

show abstract

Principal component analysis of conformations in fused ring chelate complexes: conformer identification, stereochemistry, and interconversion pathways

Harris

Pascual

Orpen

2001

J. Chem. Soc., Dalton Trans.

Self Cite

View full text Add to dashboard Cite

Data were retrieved from the Cambridge Structural Database for crystal structures containing metal complexes of ethylenediamine (en), tetramethylethylenediamine (tmeda), bis(dimethylphosphino)ethane (dmpe), bis(diphenylphosphino)ethane (dppe) chelate complexes [M(en) (279 structures, 468 fragments), M(tmeda) (156 structures, 181 fragments), M(dmpe) (205 structures, 288 fragments) and M(dppe) (273 structures, 338 fragments)] and fused five-membered chelate ring systems [complexes of diethylenetriamine, M(dien) (91 structures, 108 fragments), tris(2aminoethyl)amine, M(nn 3 ) (49 structures, 54 fragments), tris(2-diphenylphosphinoethyl)phosphine, M(pp 3 ), and tris(2-diphenylphosphinoethyl)amine, M(np 3 ) (54 structures, 56 fragments)], and have been analysed using principal component analysis (PCA) of the intra-ring torsion angles. A limited number of preferred conformers is observed for each system: enantiomeric twist conformations (δ or λ) for M(en), M(tmeda), M(dppe) and M(dmpe); three unique conformers: δδ (and its enantiomer λλ), λδ or δλ for M(dien); and two types for M(nn 3 ) or M(xp 3 ) (x = n or p): two enantiomeric C 3 symmetric A (λλλ, δδδ) and six equivalent B (δλδ, δδλ, λδδ, δλλ, λλδ, and λδλ) conformers of lower symmetry. The pseudorotation pathway for δ ↔ λ interconversion in the single ring systems is clear for M(dppe) and also for M(dmpe) but less so for M(en) and, M(tmeda). The δλ and λδ conformers of M(dien) apparently interconvert through δδ (or λλ) intermediates with one ring at a time inverting. Similarly the interconversion of conformers in the M(xp 3 ) and M(nn 3 ) systems seems likely, on the basis of the distribution of structures in conformation space, to follow a sequence δδδ ↔ δλδ ↔ λλδ ↔ λλλ (or its equivalent) but not δδδ ↔ δλδ ↔ δλλ ↔ λλλ.In the M(dien), M(nn 3 ) and M(xp 3 ) systems the conformation preferred is linked to the metal coordination geometry. In particular, the presence of an N-M-N angle approaching 180Њ in a mer-octahedral or square-based pyramid stereochemistry in M(dien) species enforces a δλ conformation. Similarly, related mer-like stereochemistry in M(nn 3 ) and M(xp 3 ) complexes leads to a B-type conformation. Longer M-N (or M-P) distances enforce more puckered, symmetrical, twist conformations of five-membered rings. A new pseudo-principal component analysis method is introduced which allows quantitative comparison of conformations in analogous but not identical ring systems. Conformations in M(en) are compared with M(dien) or M(nn 3 ), with the single-ring system exhibiting less distorted conformations. Phosphine systems exhibit greater variation of conformation than their amine counterparts. In particular M(dmpe) systems show considerably more variation than M(tmeda) whereas M(dppe) species are more varied in conformation than are M(dmpe).

show abstract

Conformational analysis of PEt3 and P(OMe)3 in metal complexes

Ellis

Haddow²,

Orpen³

et al. 2009

Dalton Trans.

Self Cite

View full text Add to dashboard Cite

The conformations of the archetypal acyclic phosphorus ligands PEt(3) and P(OMe)(3) are classified on the basis of the observation that torsions about the P-C (or P-O) bonds show favoured conformations lying close to gauche (+/-60 degrees) or anti values (180 degrees). Analysis of the symmetry of the conformation space defined by the three M-P-X-C (X = CH(2) or O) torsion angles (t(1-3)) implies the existence of seven unique conformer types (A (aaa), B (g(+)g(+)g(+)), C (ag(+)g(+)), D (aag(+)), E (g(-)ag(+)), F (ag(-)g(+)), G (g(-)g(+)g(+)) and their symmetry equivalents) arising from the combinations of g(-), g(+) and a torsions. These conformers are observed in 1972 M-PEt(3) and 735 M-P(OMe)(3) fragments from crystal structures of metal complexes in the CSD following the popularity sequence: F > C >> D > B > G > E >> A for M-PEt(3); and: C > D > F >> E >> A, B, G. for M-P(OMe)(3). Pathways for low-energy interconversion of these conformers, dominated by single chain flip routes, are readily inferred for M-P(OMe)(3). The conformers of M-PEt(3) are apparently less readily interconverted. The popularity of conformations is only loosely related to the energies of these conformations as calculated by DFT or MM methods for two-, four- (square planar) and six-coordinate metal complexes of these ligands (and free PEt(3) and P(OMe)(3)). It would appear that the conformational preferences observed are determined by a balance between intra-ligand effects (repulsion between chains and avoidance of syn-pentane-like); inter-ligand effects (repulsions between gauche substituents at P and cis co-ligands notably when the coordination number at the metal is high); and residual anomeric effects (weakly favouring anti conformations in P(OMe)(3) species).

show abstract

scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.

Contact Info

hi@scite.ai

10624 S. Eastern Ave., Ste. A-614

Henderson, NV 89052, USA

Blog Terms and Conditions API Terms Privacy Policy Contact Cookie Preferences Do Not Sell or Share My Personal Information

Made with 💙 for researchers

Part of the Research Solutions Family.

Conformational behaviour of bridging diphenylphosphido ligands

Cited by 3 publications

References 9 publications

Recognition of spatial motifs in protein structures

Recognition of spatial motifs in protein structures

Principal component analysis of conformations in fused ring chelate complexes: conformer identification, stereochemistry, and interconversion pathways

Conformational analysis of PEt3 and P(OMe)3 in metal complexes

Contact Info

Product

Resources

About