The properties of a novel Gd3+-based MRI zinc sensor are reported. Unlike previously reported Gd3+-based MRI contrast agents, this agent (GdL) differs in that the agent alone binds only weakly with human serum albumin (HSA) while the 1:2 GdL:Zn2+ ternary complex binds strongly to HSA resulting in a substantial, three-fold increase in water proton relaxivity. The GdL complex is shown to have a relatively strong binding affinity for Zn2+ (KD = 33.6 nM), similar to the affinity of the Zn2+ ion with HSA alone. The agent detects as little as 30 μM Zn2+ in the presence of HSA by MRI in vitro, value slightly more than the total Zn2+ concentration in blood (∼20 μM). This combination of binding affinity constants and the high relaxivity of the agent when bound to HSA suggests that this new agent may be useful for detection of free Zn2+ ions in vivo without disrupting other important biological processes involving Zn2+.

A Zn2+ specific GdDOTA derivative containing two bis-(3-pyrazolyl) units was prepared and characterized. Unlike a previously reported Zn2+ binding agent, the new agent binds to human albumin both in the presence and absence of Zn2+.

The methylpalladium and ‐platinum complexes [Pd(AcNac)(PMe3)CH3], [Pd(SacNac)(PMe3)CH3], and [Pt(SacNac)(PMe3)CH3] have been prepared from protonation reactions between AcNac [H3CC(O)CHC(NAr)CH3; Ar = 2,6‐iPr‐C6H3 = Dipp (L1); Ar = 2,4,6‐MeC6H2 = Mes (L2)] or SacNac [H3CC(S)CHC(NAr)CH3; Ar = 2,6‐iPr‐C6H3 = Dipp (L3); Ar = 2,4,6‐MeC6H2 = Mes (L4)] ligands and dimethyl–metal complexes of the composition [M(L′)Me2] (M = Pd, L′ = tmeda = N,N,N′N′‐tetramethylethylenediamine; M = Pt, L′ = cod = 1,5‐cyclooctadiene) and PMe3 in acetonitrile. Only one isomer was formed in each case and X‐ray crystallographic analysis showed that the PMe3 co‐ligand is found in the cis position with respect to the sulfur or oxygen atom in all complexes.

C-Br bond activation followed by a C-C coupling reaction of the 2-bromo-pyridyl unit of [1-phenyl-2-(6-bromopyridin-2-yl)-benzoimidazole] was performed by Pd(CH(2)CMe(2)-o-C(6)H(4))(η(4)-COD). Two new seven membered palladacycles were obtained. A combined experimental and theoretical DFT study elucidates the mechanism for this reaction.