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The benzene, CO, and PPh 3 adducts [HB(3-(CF 3 ),5-(Ph)Pz) 3 ]AgL (L = C 6 H 6 , CO, or PPh 3 ) have been synthesized by a metathesis process using [HB(3-(CF 3 ),5-(Ph)Pz) 3 ]Na(THF), CF 3 SO 3 Ag, and the corresponding co-ligands. These silver(I) adducts have been characterized by NMR spectroscopy, and by X-ray crystallography. In all cases the Scorpionate is bound to silver in typical κ 3 -fashion. The X-ray crystallographic data of [HB(3-(CF 3 ),5-(Ph)Pz) 3 ]Ag(η 2 -C 6 H 6 ) show that it has a η 2 -bound benzene molecule. NMR data point to fluxional behavior in solution. The 13 C NMR resonance corresponding to the CO moiety of [HB(3-(CF 3 ),5-(Ph)Pz) 3 ]Ag(CO) appears as a single peak at δ 177.4 ppm and the ν ¯ co is observed at 2148 cm −1 . These values indicate the presence of a fairly Lewis acidic silver atom in [HB(3-(CF 3 ),5-(Ph)Pz) 3 ]Ag(CO) and significantly diminished Ag → CO π-backbonding. Interesting coupling is observed in the solution 19 F and 31 P NMR spectra of the Ag(I) adduct [HB(3-(CF 3 ),5-(Ph)Pz) 3 ]Ag(PPh 3 ). A detailed analysis of the spectral and structural features of these complexes has been described herein. [ABSTRACT FROM AUTHOR]

Abstract: A DFT study on the Au–N interaction for some groups of N-donor heterocycles L {L=pyridines (py), pyrimidines (pm), imidazoles (im), pyrazoles (pz) and isoxazoles (io)} in neutral AuX3L complexes {AuX3 =AuBr3, AuCl3, trans-AuCl(CN)2, Au(CN)3} is reported. Linear relationships between the AuX3 Mulliken charge in AuX3L and the computed proton affinity (PA) of the heterocycle were found for all the considered ligands. The different slopes found on changing the N-donor species represent a measure of the π-acidity of these nitrogen ligands once coordinated to the metal centre, by the consequence a π-acceptor ability scale has been derived. The π-acceptor ability of the 5-membered N-donor ligands resulted in all the cases greater than that of the 6-membered N-heterocycles. The proton affinity average value corresponding to a zero charge of the AuX3 and L fragments in the AuX3L species has been estimated. This parameter represents the minimum PA value for the formation of a bond between the N-heterocycles and gold(III) and it does not depend on the electronic features of the coordinated ligands. The sensitivity of the AuX3 fragments towards ligands PA variations follows the order Au(CN)3 < trans-AuCl(CN)2

Abstract: A computational DFT approach for the comparison of the π-acceptor character of some N-donor heterocycles L {L=pyridines (py), pyrimidines (pm), imidazoles (im), pyrazoles (pz) and isoxazoles (io)} in neutral AuCl3L complexes is reported. The electronic properties of these ligands have been tuned by adding methyl and/or trifluoromethyl groups in various positions. Linear relationships between the Mulliken charge of the AuCl3 fragment in AuCl3L and the computed proton affinity (PA) of the heterocycle were obtained for all the considered ligands. The different slopes found on changing the N-donor type represent a measure of the π-acidity of these nitrogen ligands once coordinated to AuCl3, and as a consequence the π-acceptor ability scale pyridines≈pyrimidines

Abstract: Iron and ruthenium classical and non-classical hydrides of the type [MH(N–N)P3]+ and [M(η2-H2)(N–N)P3]2+ {M=Fe, Ru; N–N=2,2′-bipyridine (bpy), 1,10-phenanthroline (phen); P=phosphites} were reported in 2004 together with an evaluation of the pseudo-aqueous pK a values of the η2-H2 complexes. The non-classical hydrides, even if doubly charged, showed a relatively low acidity, their pK a values ranging between −5.4 and −4.3. Moreover, ruthenium(II) derivatives showed to be more acidic than the corresponding iron(II) complexes. Information about the structural and electronic proprieties of complexes of this type, which allowed to better understand the role of both the metal centres and the ancillary ligands in the acidity of the co-ordinated hydrogen molecule, was obtained on the basis of DFT B3LYP calculations. [Copyright &y& Elsevier]

Abstract: The slow diffusion reaction of a solution of FeCl3 ·6H2O in acetone into a CH2Cl2 solution of btp [2,6-bis(N1-1,2,4-triazolyl)pyridine] afforded the ferric complex, [Fe(btp)Cl3] n (1), in which the iron centre adopts a trigonal bipyramidal geometry. Three chloride ligands occupy the vertices of the trigonal plane and two nitrogen atoms of btp ligands complete the trigonal bipyramidal geometry. Interestingly, 1 shows a 3D architecture induced by non-classical C–H⋯Cl and C–H⋯N hydrogen bonds between 1D zigzag chains in which btp ligands bind ferric ions through coordination bonds. [Copyright &y& Elsevier]

Abstract: The solution reaction of btp [2,6-bis(N1-1,2,4-triazolyl)pyridine] with copper acetate afforded a secondary building unit (SBU) precursor of [Cu2(OAc)4(btp)2]·2MeOH (1) which yielded the [Cu2(OMe)2]2+ SBU by the reaction of 1 with CuX2 salts (X=[BF4]−, [ClO4]− and [OTf]−) in methanol and acetonitrile mixture. According to solid-state structural analysis, self-assembly of SBUs is dependent on the size of the anion. In the case of [BF4]− and [ClO4]−, SBUs are self-assembled to be 3D cages of [[[Cu4(μ-OMe)4(μ-btp)4(BF4)2(MeCN)2]⊃(BF4)](BF4)][[[Cu4(μ-OMe)4(μ-btp)4(BF4)(MeOH)(MeCN)2]⊃(BF4)](BF4)2] (2) and [[Cu4(μ-OMe)4(μ-btp)4(ClO4)2(MeCN)2]⊃(ClO4)](ClO4)·2H2O (3) by the anion-templating effect, where two SBUs are bridged by four btp ligands. The bending of Cu2O planes along the O⋯O hinge causes the btp ligands to get close enough to interconnect two [Cu2(OMe)2]2+ SBUs in addition to the orthogonal arrangement of Cu⋯Cu axes of each SBU. Meanwhile, the large anion [OTf]− was not capable of the 3D cage but a 1D infinite coordination polymer of [[Cu2(μ-OMe)2(μ-OTf)2(btp)2](H2O)] n (4) in which SBUs are doubly bridged by btp ligands in a zigzag pattern. [Copyright &y& Elsevier]

Abstract: A new bis(pyridylether) ligand L was synthesized in 46% yield from the reaction of two equivalents of 2-pyridylethanol with α,α′-dibromo-o-xylene in the presence of sodium hydroxide. Ligand L possesses structural features that allow it to react either intermolecularly or in a chelating fashion with transition metal ions. With AgNO3, ligand L forms a helical metallopolymer. Ligand L, in combination with 2-pyridylethanol, reacts with Cu(ClO4)2 to form a bridged dinuclear complex. With Co(NCS)2, ligand L behaves as a chelating ligand to give a monomeric octahedral complex. [Copyright &y& Elsevier]

The development of the polypyrazolylborate/scorpionate ligand system is traced from its inception, through its early and later stages of development, primarily on the basis of the author’s experiences and contributions. [Copyright &y& Elsevier]

Reactions of the Rh hydrido complex [Rh(H)2(PPh3)2(EtOH)2]ClO4 (1) with nitrogen ligands such as 2-(4-thiazolyl)benzimidazole (tbz), pyridazine (pdz), imidazole (im) and pyrimidine (pmd) in CH2Cl2 afforded various mononuclear Rh hydrido complexes, [Rh(H)2(PPh3)2(tbz)]ClO4 (2), [Rh(H)2(PPh3)2(pdz)2]ClO4·2CH2Cl2 (3), [Rh(H)Cl(PPh3)2(pdz)2]ClO4·CH2Cl2 (4), [Rh(H)2(PPh3)2(im)2]ClO4·2CH2Cl2 (5), [Rh(H)Cl(PPh3)2(im)2]ClO4·CH2Cl2 (6), [Rh(H)2(PPh3)2(pmd)2]ClO4·CH2Cl2 (7) and the Rh non-hydrido complex [RhCl2(pmd)4]ClO4 (8). The Rh complexes 2, 3, 5 and 6 were crystallographically characterized. The formation process was monitored by 1H NMR and UV–Vis spectra. In all the Rh hydrido complexes, the Rh atom is coordinated by two PPh3 ligands in trans-positions and two nitrogen ligands in the cis-positions. The remaining sites are occupied by one or two hydride atoms to form a saturated 18-electron framework in a slightly distorted octahedral geometry. For complex 2 an appreciable inter-molecular π interaction is observed between planes of tbz and PPh3 ligands, while an intra-molecular hydrogen bonding interaction between C&z.sbnd;H and Cl atoms is found in complex 6. [Copyright &y& Elsevier]