A facile one-pot synthesis of a new cryptand via a Pd(II)-catalysed carbonylation reaction.

We report the facile and efficient synthesis of a novel cryptand using a one-pot method involving a Pd(II)-catalysed carbonylation reaction. The crystal structure of the corresponding Cu(II) cryptate is also described.

The co-ordination chemistry of bis(2,2'-bipyrid-6'-yl)ketone with first row transition metals: the reversible interconversion of a mononuclear complex and a dinuclear hemiketal containing species.

Bis(2,2'-bipyrid-6'-yl)ketone has been shown to co-ordinate to Zn(II) to form either a dinuclear hemiketal complex in methanol solutions or mononuclear complexes in acetonitrile. The ligand readily complexes to the late transition metals in acetonitrile to yield mononuclear complexes (Mn(II), Co(II), Ni(II),Zn(II) and Cd(II)) however for Fe(II) only dinuclear complexes [Fe(2){(2-bipy)(2)C(OMe)O(-)}(2)][ClO(4)](2) could be isolated. The solid state structures of the mononuclear complexes exhibit varying degrees of distortion compared to an anticipated planar array of bipyridyl donors.

LZnX complexes of tripodal ligands with intramolecular RN-H hydrogen bonding groups: structural implications of a hydrogen bonding cavity, and of X/R in the hydrogen bonding geometry/strength.

Tripodal ligands N(CH2Py)3-n(CH2Py-6-NHR)n(R=H, n=1-3 L1-3, n=0 tpa; R=CH2tBu, n=1-3 L'1-3) are used to investigate the effect of different hydrogen bonding microenvironments on structural features of their LZnX complexes (X=Cl-, NO3-, OH-). The X-ray structures of [(L2)Zn(Cl)](BPh4)2.0.

Zinc(II) complexes with intramolecular amide oxygen coordination as models of metalloamidases.

Polydentate ligands (6-R1-2-pyridylmethyl)-R2(R1= NHCOtBu, R2= bis(2-pyridylmethyl)amine L1, bis(2-(methylthio)ethyl)amine L2 and N(CH2CH2)2S L3) form mononuclear zinc(II) complexes with intramolecular amide oxygen coordination and a range of coordination environments. Thus, the reaction of Zn(ClO4)2.6H2O with L1-3 in acetonitrile affords [(L)Zn](ClO4)2(L=L1, 1; L2, 2) and [(L3)Zn(H2O)(NCCH3)](ClO4)2 3.

Quantifying the relative contribution of hydrogen bonding and hydrophobic environments, and coordinating groups, in the zinc(II)-water acidity by synthetic modelling chemistry.

Ligands derived from the tripodal N4 ligand tris(pyridylmethyl)amine ((pyCH2)3N, tpa) of general formula (6-RNHpyCH2)nN(CH2py)(3-n)(R = H, n= 1-3 L(1-3); R = neopentyl, n= 1-3 L'(1-3)) were used to elucidate and quantify the magnitude of the effects exerted by hydrogen bonding and hydrophobic environments in the zinc-water acidity of their complexes. The pKa of the zinc-bound water molecule of [(L(1-3))Zn(OH2)]2+ and [(L'(1-3))Zn(OH2)]2+ 1'-3' was determined by potentiometric pH titrations in water (1-3) or water-ethanol (1:1) (1'-3'). The zinc(II) water acidity gradually increases as the number of -NH2 hydrogen bonding groups adjacent to the water molecule increases.

Relative importance of hydrogen bonding and coordinating groups in modulating the zinc-water acidity.

The presence of second-sphere -NH(2) groups in the proximity of a zinc(ii)-bound water molecule enhances its acidity by ca. 2 pK(a) units.