Structurally Diverse pi-Cyclopentadienyl Complexes of the Main Group Elements.

A metalorganic complex of the formula MAYX, wherein M is a y-valent metal; A is a monodentate or multidentate organic ligand coordinated to M which allows complexing of MAy with X; y is an integer having a value of 2, 3 or 4; each of the A ligands may be the same or different; and X is a monodentate or multidentate ligand coordinated to M and containing one or more atoms independently selected from the group consisting of atoms of the elements C, N, H, S, O and F. The metal M may be selected from the group consisting of Cu, Ba, Sr, La, Nd, Ce, Pr, Sm, Eu, Th, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, Tl, Y, Pb, Ni, Pd, Pt, Al, Ga, In, Ag, Au, Co, Rh, Ir, Fe, Ru, Sn, Li, Na, K, Rb, Cs, Ca, Mg, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W. A may be selected from the group consisting of β-diketonates and their sulfur and nitrogen analogs, β-ketoesters and their sulfur and nitrogen analogs, cyclopentadienyls, alkyls, perfluoroalkyls, alkoxides, perfluoroalkoxides, and Schiff bases. X may for example comprise a ligand such as tetraglyme, tetrahydrofuran, bipyridine, crown ether, or thioether.

Metal complex source reagents for chemical vapor deposition

Compounds of the type aryl--M--X, with M=Ca, Sr, Ba and X as any kind of ligand (such as halide, phosphanide, amide, aryl), are presented. The low reactivity of the heavy alkaline earth metals calcium, strontium, and barium enforces an activation prior to use for the direct synthesis. The insertion of these metals into C--I bonds of aryl iodides (direct synthesis) yields aryl metal iodides and has to be performed at low temperatures and in THF. Aryl alkaline-earth-metal compounds show some characteristics: 1) the ease of ether cleavage enforces low reaction temperatures, 2) for Sr and Ba the Schlenk equilibrium is shifted towards homoleptic MI2 and MPh2, 3) high solubility of diaryl alkaline-earth-metal derivatives in THF even at low temperatures initiated quantum chemical investigations on the aggregation behavior, and 4) a strong low field shift of the 13C resonances of the ipso carbon atoms in NMR spectra was observed. First results from quantum chemical calculations on diaryl dicalcium(I) suggest a long Ca--Ca bond with a considerable Ca--Ca bond dissociation energy. Initial results on a selection of applications such as metallation, metathesis, and addition reactions of aryl calcium compounds are presented as well.

Heavy Grignard Reagents: Challenges and Possibilities of Aryl Alkaline Earth Metal Compounds

New developments in the organometallic chemistry of calcium, strontium and barium

Metal organic chemical vapor deposition (MOCVD) source reagents useful for formation of metal-containing films, such as thin film copper oxide high temperature superconductor (HTSC) materials The source reagents have the formula MAyX wherein: M is a metal such as Cu, Ba, Sr, La, Nd, Ce, Pr, Sm, Eu, Th, Gd, Tb, Dy, Ho, Er, Tm Yb, Lu Bi, Tl, Y or Pb; A is a monodentate or multidentate organic ligand; y is 2 or 3; MAy is a stable sub-complex at STP conditions; and X is a monodentate or multidentate ligand coordinated to M and containing one or more atoms independently selected from the group consisting of atoms of the elements C, N, H, S, O, and F The ligand A may for example be selected from beta-diketonates, cyclopentadienyls, alkyls, perfluoroalkyls, alkoxides, perfluoroalkoxides, and Schiff bases The complexes of the invention utilize monodentate or multidentate ligands to provide additional coordination to the metal atom, so that the resulting complex is of enhanced volatility characteristics, and enhanced suitability for MOCVD applications

R.A. Williams

Papers

Solution synthesis of calcium, strontium and barium metallocenes