Kornelia Zeckert

Tin–lanthanoid donor–acceptor bonds

Reactions of a lithium tris(2-pyridyl)stannate with lanthanoid metal organic compounds resulted in the formation of novel donor-acceptor complexes, containing a low valent tin-lanthanoid bond; DFT calculations reveal that this bond exhibits some covalent character.

Lanthanide(II) complexes of a dual functional tris(2-pyridyl)stannate derivative.

Florian Reichart, Marcus Kischel, and Kornelia Zeckert* In the last decades neutral trisACHTUNGTRENNUNG(pyridyl) ligands have received considerable interest in coordination as well as organometallic chemistry. Although most of these ligands reported to date consist of nonmetallic Main Group elements in the bridgehead position, only some examples containing Main Group metals are known. Moreover, in studies of trisACHTUNGTRENNUNG(pyridyl) ligands of Group 14 elements the anionic trisACHTUNGTRENNUNG(organo)plumbate in [LiPb ACHTUNGTRENNUNG(2py)3ACHTUNGTRENNUNG(thf)][2b] (py=pyridyl) is the only example of a low oxidation state Group 14 tris ACHTUNGTRENNUNG(pyridyl) ligand so far. In principle, besides a kN-coordination by the pyridine rings, the lone pair of electrons on the bridgehead metal center of such a functionalized anionic ligand system [EACHTUNGTRENNUNG(2-py)3] (E=Sn or Pb) could be used for subsequent metal coordination, making this ligand system interesting, particularly in view of its potential dual functionality. However, the transition metal complexes based on the trialkoxymetallate compounds [E ACHTUNGTRENNUNG(OtBu)3] (with E=Ge, Sn, Pb) and very recently the complex [Li(Me2NCH2CH2O)3Sn Fe(CO)4]2 [4] are the only examples of a multidentate ligand system based on the heavier Group 14 elements with dual functionality and representing an additional kE-coordination. Herein we report on reactivity studies of the lithiumtrisACHTUNGTRENNUNG(pyridyl)stannate [LiSn(2-C5H3N-5-Me)3ACHTUNGTRENNUNG(thf)] (1) towards [Ln ACHTUNGTRENNUNG(h5-C5Me5)2ACHTUNGTRENNUNG(OEt2)] (Ln= Yb, Eu) forming novel sandwich complexes of the two divalent lanthanides. Reaction of [YbACHTUNGTRENNUNG(h5-C5Me5)2ACHTUNGTRENNUNG(OEt2)] with the lithium stannate 1 in a 1:2 stoichiometry immediately results in formation of a brown solution with concomitant elimination of LiC5Me5 (Scheme 1). After filtration and concentration of

Versatile Reactivity of a Lithium Tris(aryl)plumbate(II) Towards Organolanthanoid Compounds: Stable Lead–Lanthanoid–Metal Bonds or Redox Processes

Redox chemistry: Redox-active europium complexes based on a new tris(2-pyridyl)plumbate ligand are described. Reactions of [LiPb(2-py(R))3(thf)] (py(R) = C5H3-6-OtBu) with tri- or divalent lanthanoid metals resulted in the first stable Pb-Ln-bonded complexes or unprecedented redox reactions, involving, for example, the pentametallic complex depicted.

Calix[4]arenes with narrow rim 2-mercaptoethoxy substituents as potential precursor molecules for metallacages and sensors

Abstract The compound 5,11,17,23- tert -butyl-25,26,27,28-(2-mercaptoethoxy) calix[4]arene reacts with methylmercuric acetate to give 5,11,17,23- tert -butyl-25,26,27,28-(2-mercaptoethoxymercuriomethyl) calix[4]arene. Under vacuum this compound converts to bis-(5,11,17,23- tert -butyl-25,26,27-(2-mercaptoethoxymercuriomethyl)-28-(2-mercaptoethoxy))mercury calix[4]arene by loss of dimethylmercury. Additional loss of dimethylmercury gave a product that is intermediate between bis-(5,11,17,23- tert -butyl-25,26-(2-mercaptoethoxymercuriomethyl)-27,28-(2-mercaptoethoxy))dimercury calix[4]arene, bis-(5,11,17,23- tert -butyl-25-(2-mercaptoethoxymercuriomethyl)-26,27,28-(2-mercaptoethoxy))trimercury calix[4]arene, and the cluster bis-(5,11,17,23- tert -butyl-25,26,27,28-(2-mercaptoethoxy))tetramercury calix[4]arene ( 11 ). 5,11,17,23- Tert -butyl-25,26,27,28-(2-mercaptoethoxy) calix[4]arene reacts with 9-chloromethylanthracene to give 5,11,17,23- tert -butyl-25,26,27,28-(9-thiomethylanthracylethoxy) calix[4]arene.

Dilithium Hexaorganostannate(IV) Compounds

Hypercoordination of main-group elements such as the heavier Group 14 elements (silicon, germanium, tin, and lead) usually requires strong electron-withdrawing ligands and/or donating groups. Herein, we present the synthesis and characterization of two hexaaryltin(IV) dianions in form of their dilithium salts [Li2(thf)2{Sn(2-py(Me))6}] (py(Me)=C5H3N-5-Me) (2) and [Li2{Sn(2-py(OtBu))6}] (py(OtBu)=C5H3N-6-OtBu) (3). Both complexes are stable in the solid state and solution under inert conditions. Theoretical investigations of compound 2 reveal a significant valence 5s-orbital contribution of the tin atom forming six strongly polarized tin-carbon bonds.

Highly sensitive protein detection based on lanthanide chelates with antenna ligands providing a linear range of five orders of magnitude.

Protein detection is an important task for pharmaceutical and clinical research today. Numerous protein staining techniques exist but are limited regarding their sensitivity and often narrow linear quantification ranges. To the best of our knowledge, this is the first description of a novel class of lanthanide chelatators, which absorb in the lower energy region at 360 nm. The new compound (6,9-dicarboxymethyl-3-{4-([1,10]-phenanthrol-2-ylethinylphenyl-carbamoyl)-methyl}-3,6,9-triaza-)-undeca-1,11-dicarboxylic acid) was coupled to different proteins and showed highly sensitive protein detection limits in both sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) (1.5 fmol of bovine serum albumin) as well as Dot Blot (100 amol of lysozyme). Furthermore, the novel compound shows an exceptionally broad linear quantification range over 5 orders of magnitude allowing applications that require the highest sensitivity alongside standard sensitivity. In addition, the new compound offers multiplexing capabilities.