Complexes of Group III trimethyls with diamines

Section: Methodsmentioning

confidence: 99%

Synthesis and characterization of transition metal complexes containing novel, unsymmetric tridentate organogallate ligands

Onyiriuka¹,

Storr²

1987

“…Trimethylgallium was synthesized from gallium metal and dimethylmercury as described previously (4). Glycine (Eastman Organic Chemicals) was used as supplied.…”

Section: Starting Materialsmentioning

confidence: 99%

Synthesis and structural characterization of glycinatodimethylgallium, (C₂H₄NO₂)Ga(CH₃)₂

Rettig¹,

Storr²,

Trotter³

1987

. Can. J. Chem. 65, 1349Chem. 65, (1987. Details of the preparation and crystal structure of the title compound are given. Crystals of glycinatodimethylgallium are monoclinic, a = 12.502(1), b = 12.023(1), c = 10.732(1) A, P = 110.05(1)", Z = 8, space group P 2 1 / c . The structure was solved by conventional heavy atom methods and was refined by full-matrix least-squares procedures to R = 0.033 and R,,, = 0.039 for 1172 reflections with I ? 3u(I). The structure consists of monomeric (C2H4N02)GaMe2 molecules which are linked together by an extensive network of N-H...O hydrogen bonds. The Ga atoms have tetrahedral coordination geometry with bond lengths averaged over the two crystallographically independent molecules: Ga-0 = 1.958(18), Ga-N = 2.031(5), and Ga-C = 1.937(7) A. IntroductionThe importance of a-amino acids as the principal constituents of protein and living matter is unquestionable. One such protein, transferrin (a glycoprotein of molecular weight -80 OOO), is responsible for iron transport in mammalian systems and has been implicated in the transport of gallium in vivo (1, 2).Recently we have been interested in the area of gallium citrate chemistry (3), primarily since gallium citrate complexes are important clinical agents in medicinal chemistry (1) and definitive structural data on such complexes was entirely lacking. Our attention has also focussed on the coordination chemistry of gallium species with simple a-amino acids with a view to elucidating the binding of gallium by such compounds. The present paper details the preparation and structural characterization of the glycinatodimethylgallium complex. ExperimentalAir-sensitive materials were handled under oxygen-free dry nitrogen or on a high-vacuum line. Benzene was dried by refluxing over molten potassium followed by distillation under an atmosphere of nitrogen. Starting materialsTrimethylgallium was synthesized from gallium metal and dimethylmercury as described previously (4). Glycine (Eastman Organic Chemicals) was used as supplied. Synthesis of glycinatodimethylgalliumMe3Ga (1.325 g, 11.55 mmol) was condensed onto glycine (0.866 g, 11.55 mmol) at -196OC. Alternate warming and cooling resulted in a vigorous reaction well below room temperature, with evolution of methane:Yield 70%. Anal. calcd. for (C2H4N02)GaMe2: C 27.60, H 5.76, N 8.06; found: C 27.69, H 5.83, N 7.93. Mass spectrumThe mass spectrum displayed as its highest m/e signal one due to the monomer -Me' ion. In addition signals from ions arising from the expected fragmentation of the monomer species were also observed. X-ray crystallographic analysisCrystals were sealed under dry nitrogen in glass capillaries. A crystal bounded by the eight faces (followed by the distances in mm between (extended by 25% on both sides for background measurement) was employed. Data were measured to 20 = 50". The intensities of three check reflections, measured every 3600 s throughout the data collection, decreased uniformly by 18.5%, the data being scaled accordingly. After data reduction,' an abso...

“…The purity of the products was checked by correlation of their ir and nmr spectra with reference data. Trimethylgallium (2) and dimethylgallium hydroxide (3) were made by standard methods.…”

Section: Starting Materialsmentioning

confidence: 99%

Synthesis, characterization, and structural studies of gallium citrate complexes

Banta¹,

Rettig²,

Storr³

et al. 1985

. Can. J. Chem. 63, 2545Chem. 63, (1985. The synthesis and physical properties of two dimethylgallium citrate triester complexes are reporttd. Crystals of bis-[(trimethylcitrato)dimethylgallium(III)] are monoclinic, a = 9.839(1), b = 14.496(1), c = 11.125(1) A, P = 108.31(1)", Z = 2, space group P2]/c. The structure was solved by conventional heavy-atoms methods and was refined by full-matrix least-squares procedures to R = 0.036 and R,, = 0.037 for 1507 reflections with I 2 3u(I). The structure consists of centrosymmetric dimers in which each citrate ligand is coordinated via the hydroxyl oxygen (bridging) and the C=O oxygen atom of the central ester group, forming five-membered chelate rings. Each Ga atom has irregular trigonal bipyramidal coordination geometry with Ga-O(eq) = 1.950(3), Ga-O(ax) = 2.103(3) and 2.395(3), and Ga-C(eq) = 1.953 (5) IntroductionThe importance of gallium citrate complexes in medicinal chemistry is well documented (I), but definitive stmctural studies in this area are lacking. In our continuing investigations of the coordination chemistry of gallium the synthesis of two crystalline dimethylgallium citrate triester complexes has been accomplished. The mode of binding of the dimethylgallium moiety in the methyl citrate triester has been determined through an X-ray structural study.