Misassigned C–H⋯Cu agostic interaction in a copper(<scp>ii</scp>) ephedrine derivative is actually a weak, multicentred hydrogen bond

Thakur, Tejender S.; Desiraju, Gautam R.

doi:10.1039/b514427b

Cited by 104 publications

(58 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These delocalisation energies are insignificant compared with those obtained for strong agostic interactions and are comparable with C-H···M hydrogen-bonding interactions. [29,30] The "atoms in molecules" theory [31] has also been used for further probing of the topological properties of the CH···Ni interaction in 1 and 2. The values obtained for the electron densities (ρ b = 0.011 and 0.012 a.u.…”

Section: Computational Resultsmentioning

confidence: 99%

“…for 1 and 2, respectively) at the bond critical points are well within the range reported for C-H···M interactions that are hydrogen bonds in character. [30,[32][33][34][35] Proton NMR Spectroscopic Studies NMR spectroscopy is a useful tool for the diagnosis of the agostic or hydrogen-bond character of C-H···M interactions in square-planar d 8 metal ion complexes. The proton resonance shifts to an up-field position for agostic interactions while it shifts down-field for hydrogen-bond interactions compared with that of the free C-H group.…”

Section: Computational Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Intramolecular Apical C–H···M Interactions in Square‐Planar Nickel(II) Complexes with Dianionic Tridentate Ligands and 2‐Phenylimidazole

Mukhopadhyay

Pal

2006

Eur J Inorg Chem

View full text Add to dashboard Cite

Keywords: Nickel(II) complexes / Square-planar complexes / Apical C-H···Ni interactions / X-ray structures / Theoretical calculations and sp 2 N-donor 2-phenylimidazole (phim) as the ancillary ligand have been synthesised and characterised by analytical, spectroscopic, magnetic and electrochemical methods. The solid-state structures of both complexes have been determined by X-ray crystallography. The asymmetric unit of 1 contains a single complex molecule while that of 2 contains four complex molecules with different conformations. The molecular structures of both complexes reveal that one of the two ortho C-H groups of the pendant phenyl ring of the phim ligand is very close to the metal centre at the apical site indicating the presence of an intramolecular C-H···Ni interaction. In the structures of 1 and 2, the shape of the C-H···Ni interaction is determined by the twisting of the phim ligand and the extent of orthogo- IntroductionThe long standing interest in the interaction of transition metal ions with proximate C-H fragments is primarily due to the C-H activation processes involved in many catalytic reactions. Such interactions have been scrutinised intensively for a better understanding of their structural and bonding features. [1][2][3][4][5][6][7][8][9][10][11][12] The C-H···M interaction in coordinatively unsaturated and electron-deficient (16-electron) species is called an agostic interaction or agostic bond where the filled C-H σ orbital interacts with an empty metal orbital. In these agostic interactions, generally the C-H fragment is side-on to the metal ion. This T-shape of the agostic C-H···M interaction facilitates the involvement of the filled metal dπ orbital and the empty C-H σ* orbital in back bonding. However, the nature of the apical C-H···M interactions in square-planar 16-electron complexes of d 8 metal ions is not very clear. [9][10][11][12] In such species, these interactions can be agostic bond (three-centre two-electron) as well as non-classical hydrogen bond (three-centre four-elec- [a]

show abstract

Section: Computational Resultsmentioning

confidence: 99%

Section: Computational Resultsmentioning

confidence: 99%

Intramolecular Apical C–H···M Interactions in Square‐Planar Nickel(II) Complexes with Dianionic Tridentate Ligands and 2‐Phenylimidazole

Mukhopadhyay

Pal

2006

Eur J Inorg Chem

View full text Add to dashboard Cite

show abstract

“…This is a well-known behaviour of hydrogen atoms positioned close to copper carboxylato complexes. [26] A rather similar example [Cu(Hceph) 2 ] has been discussed into details by Desiraju and Thakur. [ 26] Polymerisation of MMA in the presence of 6 leads only to very small amounts of a blue-green glassy and viscous material with high nitrogen content indicating nearly no incorporation of MMA.…”

Section: Copolymersmentioning

confidence: 99%

“…[26] A rather similar example [Cu(Hceph) 2 ] has been discussed into details by Desiraju and Thakur. [ 26] Polymerisation of MMA in the presence of 6 leads only to very small amounts of a blue-green glassy and viscous material with high nitrogen content indicating nearly no incorporation of MMA. Copper complexes are well-known to act as atom transfer radical polymerisation (ATRP) catalysts, monoanionic copper complexes with nitrogen and oxygen donors are even deliberately used in ATRP.…”

Section: Copolymersmentioning

confidence: 99%

Novel N,N,O Scorpionate Ligands and Transition Metal Complexes Thereof Suitable for Polymerisation

et al. 2008

View full text Add to dashboard Cite

Esterification of 2,2‐bis(3,5‐dimethylpyrazol‐1‐yl)‐3‐hydroxypropionic acid (2) with methacryloyl chloride led to the new κ3‐N,N,O ligand 2,2‐bis(3,5‐dimethylpyrazol‐1‐yl)‐3‐methacrylato‐propionic acid (Hbdmpzmp) (3). The κ3‐N,N,O coordination as known from bis(3,5‐dimethylpyrazol‐1‐yl)acetic acid (Hbdmpza, 1) was proven by syntheses of the complexes [Mn(bdmpzmp)(CO)3] (4) and [Re(bdmpzmp)(CO)3] (5) and the single‐crystal X‐ray structure of 4. The methacrylic ester functionality makes 3, 4 and 5 suitable for polymerisation. Thus, copolymerisation of 3 with methyl methacrylate (MMA), a combination of MMA and ethylene glycol dimethacrylate (EGDMA) or pure EGDMA led to various solid phases (P1a–P1c, P2, P3a, P3b) with incorporated ligand. Polymer‐bound manganese and rhenium tricarbonyl complexes could be obtained by copolymerisation of 4 and 5 with MMA as well as by a polymer analogous reaction of P1a with appropriate metal salts. In both cases, the facial tripodal binding behaviour was evidenced by IR spectra of the polymer supported transition metal complexes and the uptake of manganese was proven by AAS measurements. Reaction of the soluble deprotonated solid phase P1a with copper(II) chloride led to a deep‐blue solid phase (P‐Cu‐I). The UV/Vis absorption maximum at 715 nm indicates the copper centres to act as crosslinking agent by a similar binding behaviour as in [Cu(bdmpza)2]. In contrast, the heterogeneous reaction of P1b with copper(II) chloride formed a lime‐green solid phase (P‐Cu‐II). The bathochromic shift of the absorption maximum by 78 nm suggests one‐sided bound copper centres. EPR spectra do not show exchange narrowing between the copper centres indicating the metal centres to be far enough apart from each other to prevent magnetic interactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

show abstract

“…Therefore, such interactions, especially in square planar d 8 systems, have been described by some authors as ''weak hydrogen bonds.'' According to this description the interactions are considered to be 3-center/4-electron in nature, the metal acting as an electron pair donor [23][24][25][26][27]. Other authors, while agreeing that the related N-HÁÁÁM interactions are best described as being akin to hydrogen-bonding, view the C-HÁÁÁM situation as being less clear [28,29].…”

Section: X-ray Crystallographymentioning

confidence: 99%

Cu(I)···H–C Bonding in Cu(2,3-Diphenylquinoxaline)ClO4

2014

View full text Add to dashboard Cite

Copper(II) perchlorate was comproportionated with copper metal in the presence of 2,3-diphenylquinoxaline (Ph 2 Qox) to produce two 1-D polymeric Cu(I) complexes, depending on reaction conditions used. Red complex 1, Cu(Ph 2 Qox)ClO 4 , crystallized in the monoclinic P2 1 /n space group with cell parameters: a = 8.6254(4) Å , b = 17.4097(7) Å , c = 11.9174(5) Å , b = 103.3050(16), V = 1,741.55(13) Å 3 , and Z = 4. It contains a Cu-O perchlorate bond and shows a remarkably close interaction of C-H with Cu. The latter interaction is best described as a weak hydrogen bond between C-H and the metal center. In addition, weak hydrogen bonding is seen between the same C-H and two of the ClO 4 oxygen atoms. Complex 2, [Cu(Ph 2 Qox)(H 2 O)]ClO 4 Á0.5CH 2 Cl 2 , crystallizes as a racemic twin in the orthorhombic P2 1 2 1 2 space group with cell parameters: a = 12.8184(10) Å , b = 17.5539(14) Å , c = 9.1166(7) Å , V = 2,051.4(3) Å 3 , and Z = 2. It contains non-coordinated perchlorate. Hydrogen bonding produces (H 2 O) 2 (ClO 4 ) 2 rings that bridge the polymer chains into sheets.

show abstract

Misassigned C–H⋯Cu agostic interaction in a copper(ii) ephedrine derivative is actually a weak, multicentred hydrogen bond

Abstract: Agostic interactions and weak hydrogen bonds to metal acceptors, M, are chemically and geometrically distinct, and this distinction must be maintained in the classification of new C-H...M interactions.

Cited by 104 publications

References 22 publications

Intramolecular Apical C–H···M Interactions in Square‐Planar Nickel(II) Complexes with Dianionic Tridentate Ligands and 2‐Phenylimidazole

Intramolecular Apical C–H···M Interactions in Square‐Planar Nickel(II) Complexes with Dianionic Tridentate Ligands and 2‐Phenylimidazole

Novel N,N,O Scorpionate Ligands and Transition Metal Complexes Thereof Suitable for Polymerisation

Cu(I)···H–C Bonding in Cu(2,3-Diphenylquinoxaline)ClO4

Contact Info

Product

Resources

About