Ruthenium(II) and osmium(II) polypyridyl complexes of an asymmetric pyrazinyl- and pyridinyl-containing 1,2,4-triazole based ligand. Connectivity and physical properties of mononuclear complexes (original) (raw)
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Dalton Transactions, 2003
The X-ray crystal structure of the N 2 isomers of the Ru(bipy) 2 complexes of Hphpztr (1) and Hpztr (2), (bipy = 2,2Јbipyridine, Hphpztr = 2-(5Ј-phenyl-4ЈH-[1,2,4]triazol-3Ј-yl)pyrazine and Hpztr = 2-(4ЈH-[1,2,4]triazol-3Ј-yl)pyrazine) are reported. The molecular structure obtained for 2 demonstrates an interesting structural aspect in the sharing of a single proton between two molecular units. The isolation of the ∆ and Λ stereoisomers of 1 and [Ru(phen) 2 (pztr)] ϩ (phen = 1,10-phenanthroline) (3) by semipreparative HPLC is also reported. The compounds obtained are characterised by electronic spectroscopy and particular attention is paid to the photophysical properties of ∆ and Λ isomers of 1 and 3, in chiral enantiopure and racemic solvents.
Inorganica Chimica Acta, 2017
A series of new mono, di thienyl pyrazole (L1) and bridged furyl pyrazole (L2) complexes of arene ruthe-nium, rhodium and iridium {arene = benzene, p-cymene and Cp ⁄ } have been synthesized and characterized by spectroscopic techniques. The formulations of these mono and di thienyl pyrazole complexes are as follows: [(arene)M(L1)Cl 2 ], where M = Ru, arene = benzene (1), p-cymene (2); M = Rh, arene = Cp ⁄ (3) and M = Ir, arene = Cp ⁄ (4) [(arene)M(L1) 2 Cl]Cl, where M = Ru, arene = benzene (5), p-cymene (6); M = Rh, arene = Cp ⁄ (7) and M = Ir, arene = Cp ⁄ (8). The bridged furyl pyrazole complexes are formulated as [{(arene)MCl} 2 L2]PF 6 , where M = Ru, arene = benzene (9), p-cymene (10); M = Rh, arene = Cp ⁄ (11) and M = Ir, arene = Cp ⁄ (12). The structure of the complexes 1–7 and 10 has been established by single crystal X-ray diffraction studies. The orbital occupancy over the metal on complexation and energy gap between HOMO and LUMO of the complexes 1–6 have been analyzed by the density functional theory (DFT). The variation of the heterocyclic moiety in pyrazole ligands significantly alters bonding mode of the ligand. The in vitro antibacterial activity of the complexes 1–6 has been measured by the agar well diffusion assay by using human pathogenic gram-negative and gram-positive bacterial strains. The binding ability of the complexes 1–6 to the CT-DNA has been carried out by using various biophysical techniques viz. UV–Visible, fluorescence spectroscopy and agarose gel electrophoresis.
Polyhedron, 1997
Under mild conditions [ReX(CO),(THF),] reacts with pyrazolylmethylpyridines to form the complexes fat-[ReX(CO),(BPz)] and fat-[ReX(CO),(BMPz)] (X = Cl, Br, or I; BPz = 2,6-bis(pyrazol-l-ylmethyl)pyridine ; BMPz = 2,6-bis(3,5-dimethylpyrazol-1-ylmethyl)pyridine) that involve BPz and BMPz acting as non-fluxional bidentate chelate ligands. Under more severe reaction conditions fuc-[ReX(CO),(BPz)] is converted to@-[Re(CO),(BPz)]X (X = Cl, Br, or I). Trimethylplatinum(IV)iodide reacts with BPz to form fuc-[PtMe,(BPz)]I. The crystal structure offac-[ReI(CO)3(BMPz)] confirms the bidentate chelate bonding of BMPz with a N-Re-N angle of 85.8". 0 1997 Elsevier Science Ltd Keywords: rhenium; platinum; pyridine; pyrazol-1-yl.
Transition metal complexes with pyrazole-based ligands. Part 6
Thermochimica Acta, 1998
The synthesis, IR-spectra and thermal analysis of tetrahedral or octahedral Cd(II)-complexes of 3(5)-amino-5(3)methylpyrazole (L), as represented by the general formula CdX 2 L 2 ÁnH 2 O (X NCS À , NCO À , Cl À , n2; 1/2 SO 2À 4 , n1), and of the complex Cd(OAc) 2 L 3 ÁH 2 O are described. Thermal decomposition of the acetato complex results in an intermediate, appearing in the 480±580 K range. On the basis of the IR-spectrum and the results of elemental analysis of the intermediate, a decomposition scheme is proposed. Because of the involvement of a different anion, the thermal decomposition of the other complexes differs from that of the acetato complex. # 1998 Elsevier Science B.V.
Inorganic Chemistry, 1991
A number of orthometalated rhodium compounds of general formula [ R~(~~Y)~(L) ] (P F~) , with ppy = pyridin-2-yl-2-phenyI and L = 3-(pyridin-2-yl)-l,2,4-triazole (Ll), l-methyl-5-(pyridin-2-yl)-1,2,4-triazole (L2), l-methyl-3-(pyridin-2-yl)-l,2,4-triazole (L3). 4-methyl-3-(pyridin-2-yl)-1,2,4-triazole (L4), 3-methyl-5-(pyridin-2-yl)-1,2,4-triazole (L5), 3-(pyridin-2-yl)-5-phenyl-1,2,4-triazole (L6), 3-(pyridin-2-yl)-5-(3-nitrophenyl)-1.2,4-triazole (L7), and 3-(pyridin-2-yl)-5-(2-thienyl)-l ,2,4-triazole (L8) are reported. NMR spectroscopy has been used to characterize the coordination modes of the ligands in the complexes. The reduction potentials of the coordinated triazole ligands have been determined electrochemically, and a linear correlation between the first reduction potentials of the several [Rh(ppy),(L)]+ and [Ru(L)J2+ complexes has been observed. The similar energies for the lowest energy absorption bands (c = 6000 M-' cm-l) for all complexes suggest that this band is due to a Rhppy(r*) MLCT transition. Emission measurements have revealed that phenylpyridine-based-ligand-centered luminescence is present at 77 K.
Polyhedron
The p-tolyldiazenido ruthenium(II) complexes [RuCl3(PPh3)2(N2PhCH3)]·CH3OH (1), [RuCl3(PPh3)(N2PhCH3)(HPz)] (2) and [RuCl3(PPh3)(N2PhCH3)(Im)]·CH3OH (3) were synthesized and characterized by IR, 1H, 13C, 31P NMR, electronic absorption and emission spectroscopy, and X-ray crystallography. In the molecular structure of complex (1) some π–π stacking interactions are observed, whereas in the structure of the imidazole complex (3) graph set analysis shows intermolecular hydrogen bonded rings. The electronic structures of the complexes were calculated by DFT based on their crystal structures. The spin-allowed singlet–singlet electronic transitions of the complexes were calculated by time-dependent DFT and the UV–Vis spectra have been discussed on this basis. The emission properties of the complexes were also studied.