Novel rhodium, iridium, and ruthenium half-sandwich complexes containing (N,N)-bound picolinamide ligands have been prepared for use as anticancer agents The complexes show promising cytotoxicities, with the presence, position, and number of halides having a significant effect on the corresponding IC50 values One ruthenium complex was found to be more cytotoxic than cisplatin on HT-29 and MCF-7 cells after 5 days and 1 h, respectively, and it remains active with MCF-7 cells even under hypoxic conditions, making it a promising candidate for in vivo studies

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Rhodium, Iridium, and Ruthenium Half-Sandwich Picolinamide Complexes as Anticancer Agents

The two-dimensional mixed-ligand network catena-[(μ-4,4′-bipyridine)-bis(μ-L-tryptophanato-κ3N,O,O′)-diaqua-dicopper(II) dinitrate] is constructed through the bridging action of both the tridentate amino carboxylato and the bidentate 4,4′-bipyridine ligand. The enantiomeric L-tryptophanato ligand acts as an N,O chelate towards one copper atom and bridges through the second carboxylate oxygen atom to the adjacent copper ion. Stacking of the corrugated nets creates channels which are occupied by the hydrogen-bonded and very weakly Cu-coordinating nitrate ions.

Chiral Coordination Polymers with Amino Acids

The dimeric complex acetato(η4-cycloocta-1,5-diene)rhodium(I), [Rh(O2CMe)(η4-cod)]2 (cod = cycloocta-1,5-diene) reacts with N,O-chelating Schiff-base ligands or with N-phenylglycine to afford the diminato- or aminocarboxylato(η4-cycloocta-1,5-diene)rhodium(I) complexes [{Rh(η4-cod)}2(salen)] (1), [{Rh(η4-cod)}2(salophen)] (2), [Rh((S)-N-phenylglycinato)(η4-cod)] (3S), [Rh(rac-N-phenylglycinato)(η4-cod)] (3rac), [Rh((R)-N-(4-methoxphenyl)ethyl-2-oxo-1-naphthaldiminato)(η4-cod)] (4) and [Rh(N-(o-tolyl)-2-oxo-1-naphthaldiminato)(η4-cod)] (5) [salen2− = N,N′-ethylene-bis(salicylaldiminato), salophen2− = N,N′-(1,2-phenylene)-bis(salicylaldiminato)]. The complexes are characterized by IR-, UV/Vis-, 1H/13C-NMR- and mass-spectroscopy. Complexes 1, 2, 4 and 5 contain six-membered metallaaromatic Rh–(N–CCC–O)-chelate rings which accept C–H⋯π contacts. The crystal structure of 2 presents a polymorph (dimorph) (2a) to a previously reported structure (2b, CSD refcode SCLIRB10). Polymorphic forms 2a and 2b are traced to a different interlocking of adjacent dinuclear molecules with their corrugated van der Waals surface. The achiral N-phenylglycine ligand gives a chiral N-phenylglycinato complex [Rh(O2C–CH2–NHPh)(η4-cod)] (3) with the nitrogen atom becoming the stereogenic center upon metal coordination. Complex 3 can crystallize as the enantiomorph 3S in the tetragonal, chiral space groupP41 in a spontaneous resolution of the racemic mixture into homo-chiral helix-enantiomers due to inter-molecular N–H⋯O hydrogen bonding which connects only molecules of the same (S-) configuration into (right-handed or P-) 41-helical chains. Variation of the crystallization conditions gives 3 as a racemic polymorphic 3rac. R- and S-complexes 3 assemble in the polymorph 3rac in parallel chains along the 21-axes through N–H⋯O hydrogen bonding. Again, only molecules of the same configuration are combined into a chain, albeit neighboring chains have complexes of opposite configuration. The chiral enantiomeric naphthaldiminato complex 4 displays a herring-bone arrangement. Achiral compound 5 crystallizes in the non-centrosymmetric polar space groupCc where all molecules show the same orientation.

Polymorphs, enantiomorphs, chirality and helicity in [Rh{N,O}(η4-cod)] complexes with {N,O} = salicylaldiminato Schiff base or aminocarboxylato ligands

Bidentate enantiopure Schiff base ligands, (R or S)-N-1-(Ar)ethyl-2-oxo-1-naphthaldiminato-κ2N,O, diastereoselectively yield Δ/Λ-chiral four-coordinated, non-planar Cu(N^O)2 complexes [Ar = C6H5R/S-L1, m-C6H4OMe R-L2, p-C6H4OMe R/S-L3, and p-C6H4Br R/S-L4]. Two N,O-chelate ligands coordinate to the copper(II) atom in distorted square-planar mode, and induce metal-centered Δ/Λ-chirality at the copper atom in the C2-symmetric complexes. In the solid state, the R-L1 (or R-L4) ligand chirality diastereoselectively induces a Λ-Cu configuration in Λ-Cu-R-L1 (or Λ-Cu-R-L4), the S-L1 ligand a Δ-Cu configuration in Δ-Cu-S-L1, forming enantiopure crystals upon crystallization. Conversely, the R-L2 ligand combines both Λ/Δ-Cu-R-L2 as a diastereomeric pair in the crystals. In solution, electronic circular dichroism (CD) spectra show full or partial diastereoselectivity towards Λ-Cu for R ligands and towards Δ-Cu for S ligands. The electronic CD spectra measured on all complexes obtained from R ligands (or S ligands), e.g.Cu-R-L1, Cu-R-L2, Cu-R-L3, and Cu-R-L4 (or Cu-S-L1, Cu-S-L3, and Cu-S-L4), show consistent spectral features. TDDFT calculations of the electronic CD spectra for the diastereomers Λ-Cu-R-L1 and Δ-Cu-R-L1 suggest that the CD spectra are largely dominated by the configuration at the metal center (Λvs.Δ). The experimental CD spectrum of Cu-R-L1 agrees well with the one calculated for the Λ-Cu-R-L1 configuration. Cyclic voltammetry of Cu-R-L1 reveals a quasi-reversible redox wave corresponding to one-electron transfer for the [CuIIL2]0/[CuIL2]−1 couple in acetonitrile. DSC analyses for the complexes show an exothermic peak between 377 and 478 K (ΔH = −12 to −43 kJ mol−1), corresponding to a phase transformation from distorted square-planar/tetrahedral to regular tetrahedral geometry on heating.

Induced chirality-at-metal and diastereoselectivity at Δ/Λ-configured distorted square-planar copper complexes by enantiopure Schiff base ligands: combined circular dichroism, DFT and X-ray structural studies.

The antimicrobial activities of the cinnamaldehyde adducts with amino acids

The complexes [M(CO)4(pyridyl-CH=N-CHRCO2R′)] (M = Cr, Mo; R = H, CH3, CH(CH3)2, CH2CH(CH3)2) were obtained by reaction of the Schiff bases from pyridine-2-carboxaldehyde and glycine, L-alanine, L-valine or L-leucine esters with the norbornadiene complexes [M(CO)4(nbd)] and were characterized by IR, 1H and 13C NMR and UV-vis spectra. The deeply colored complexes exhibit solvatochromism.

Metal Complexes with Biologically Important Ligands. CLXVI Tetracarbonyl Complexes of Chromium(0) and Molybdenum(0) with Schiff Bases from Pyridine-2-carboxaldehyde and α-Amino Acid Esters as N,N-Chelate Ligands†

Die Addition von [Ph2C=NCHCO2Me]– an [(C6H7)Fe(CO)3]+, [(C7H9)Fe(CO)3]+, [(C7H7)M(CO)3]+ (M = Cr, Mo) und [(C2H4)Re(CO)5]+ liefert Derivate von α-Aminosauren mit metallorganischen Seitenketten. Die Struktur von [(η4-C6H7)CH(N=CPh2)CO2Me]Fe(CO)3 wurde rontgenographisch bestimmt. Aus dem Addukt von [(C7H7)Mo(CO)3]+ und [Ph2C=NCHCO2Me]– wird die Schiff-Base einer neuen, nichtnaturlichen α-Aminosaure, Ph2C=NCH(C7H7)CO2Me, erhalten.

Addition des O'Donnell Reagenzes [Ph2C=NCHCO2Me]– an π-koordinierte, ungesättigte Kohlenwasserstoffe in [(C6H7)Fe(CO)3]+, [(C7H9)Fe(CO)3]+, [(C7H7)M(CO)3]+ (M = Cr, Mo) und [(C2H4)Re(CO)5]+. α-Aminosäuren mit metallorganischen Seitenketten

Metallkomplexe mit biologisch wichtigen Liganden, CXXVII

Kohlenwasserstoffverbrückte metallkomplexe: XXXVII. Mono- und dimetallierte Heterocyclopentedione mit Molybdän-, Wolfram-, Mangan- und Rheniumcarbonylen

Metal Complexes of Biologically Important Ligands. Part 117. Addition of the O′Donnell Reagent [Ph2C=NCHCO2Me]‐ to Coordinated, Unsaturated Hydrocarbons of [(C6H7)Fe(CO)3]+, [C7H9Fe(CO)3]+, [(C7H7)M(CO)3]+ (M: Cr, Mo), and [(C2H4)Re(CO)5]+. α‐Amino Acids with Organometallic Side Chains.

Theodor Ederer

Papers

Metal Complexes with Biologically Important Ligands. CLXVI Tetracarbonyl Complexes of Chromium(0) and Molybdenum(0) with Schiff Bases from Pyridine-2-carboxaldehyde and α-Amino Acid Esters as N,N-Chelate Ligands†

Addition des O'Donnell Reagenzes [Ph2C=NCHCO2Me]– an π-koordinierte, ungesättigte Kohlenwasserstoffe in [(C6H7)Fe(CO)3]+, [(C7H9)Fe(CO)3]+, [(C7H7)M(CO)3]+ (M = Cr, Mo) und [(C2H4)Re(CO)5]+. α-Aminosäuren mit metallorganischen Seitenketten

Metallkomplexe mit biologisch wichtigen Liganden, CXXVII

Kohlenwasserstoffverbrückte metallkomplexe: XXXVII. Mono- und dimetallierte Heterocyclopentedione mit Molybdän-, Wolfram-, Mangan- und Rheniumcarbonylen

Metal Complexes of Biologically Important Ligands. Part 117. Addition of the O′Donnell Reagent [Ph2C=NCHCO2Me]‐ to Coordinated, Unsaturated Hydrocarbons of [(C6H7)Fe(CO)3]+, [C7H9Fe(CO)3]+, [(C7H7)M(CO)3]+ (M: Cr, Mo), and [(C2H4)Re(CO)5]+. α‐Amino Acids with Organometallic Side Chains.