Coordination Compounds of Germanium(IV) Formed with Soft and Hard Donor Atoms: A Look into the Past and Present Work

Abstract

An account of approximately hundred germanium and organogermanium derivatives have been included in this review. The unimolar and bimolar substitution products have been characterized by elemental analyses, conductance measurements, molecular weight determinations and spectral studies, viz., IR, 'H NMR, 13 C NMR, U.V. and mass spectra. Thermal stability has been explained on the basis of TGA data.From the analyses of these studies the donor sites of the ligands are located and geometries of the donor environment around the Ge(IV) acceptor centre have been proposed. Based on these studies, trigonal bipyramidal and octahedral geometries have been proposed for the resulting derivatives. The resulting coloured solids are soluble in most of the common organic solvents. These were found to be monomers, as evidenced by their molecular weight determinations. The low values of molar conductance of the resulting metal complexes in anhydrous DMF show them to be non-electrolytes in nature. The spectral data suggested that the ligands act in monofunctional bidentate, bifunctional tridentate and Afunctional tetradentate manners, coordinating through the hard nitrogen and soft sulfur atoms. All such important aspects, including the biological properties about the germanium complexes synthesized in our laboratory as well as other laboratories, are discussed in brief.

Physiological Activity of Trace Element Germanium Including Anticancer Properties

“…This review specifically focuses on the latest research conducted within the past decade, during which inorganic and coordination compounds of germanium have been incorporated into medical practices alongside water-soluble organic germanium compounds [3,45,46].…”

Stability Constants of Tetravalent Germanium Complexes in Aqueous Solution: Small Organic Oxygen and Nitrogen Donor Ligands

“…This mainly applies to the complexes previously studied by Pokrovski et al Germanium­(IV) tartrate represents a special case in that we see new and clear evidence for a dimeric complex, i.e., a dinuclear bis­(tartrato)­germanium­(IV) anion, whose existence and structure in the solid state are established by X-ray diffraction (XRD), and it is difficult to imagine any alternative structure adoptable in the aqueous phase. A number of reviews on the organometallic and solid-state coordination chemistry of Ge­(IV) illustrate the bewildering variety of coordination numbers and structures that this element is capable of producing, − for instance, a square-pyramidal geometry in anionic pentacoordinate Ge­(IV) compounds, in addition to the more commonly observed trigonal-bipyramidal structure. , In general, the existence of a particular species in the solid state does not guarantee its existence as an aqueous species, nor is the reverse necessarily true: good cases in point are the Ge­(IV) catechol complexes (see the Results and Discussion).…”

Physiological Activity of Trace Element Germanium Including Anticancer Properties

“…This review specifically focuses on research conducted within the past decade, during which inorganic and coordination compounds of germanium have been incorporated into medical practices alongside water-soluble organic germanium compounds [3,45,46]. Moreover, the toxicity of germanium compounds has been the subject of much controversy and confusion, and the discovery history of stable water-soluble germanium compounds has been significantly distorted.…”