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A 2,4-Diazadiboretidine contains an alternating four-membered B–N–B–N ring. nitrogen lone pairs provide sigma-donor sites, while the ring can bind an electron-rich metal through a pi interaction involving both B and N.

A material combining a metal with one or more other chemical elements, while retaining metallic properties.

Beta-hydride elimination transfers hydrogen from the beta carbon of a metal-bound alkyl to the metal while forming an alkene. It can release a growing polymer chain and compete with migratory insertion. Its accessibility depends on geometry, available sites and bond energetics.

B. Gemünd coauthored research on gallium.^[ref]

Gallium is the chemical element with atomic number 31 and symbol $\mathrm{Ga}$. It is a metal. Its melting point lies just above ordinary room temperature. Compounds such as gallium nitride are important semiconductors; their electronic properties arise from the compound lattice, not from the low melting point of elemental gallium.

B. Günther coauthored research on gallium.^[ref]

Gallium is the chemical element with atomic number 31 and symbol $\mathrm{Ga}$. It is a metal. Its melting point lies just above ordinary room temperature. Compounds such as gallium nitride are important semiconductors; their electronic properties arise from the compound lattice, not from the low melting point of elemental gallium.

A bidentate ligand binds a metal through two donor atoms. Simultaneous attachment can produce a chelate ring; the two donor atoms need not be the same element.

A binary alloy is a metallic material whose specified alloy system has two elemental components. “Binary” counts components, not phases: one composition may form a single solid solution, while another or a different temperature can produce two coexisting phases.

If an overall component fraction $x_0$ lies between equilibrium phase compositions $x_{\alpha }$ and $x_{\beta }$, conservation of material gives the phase fractionThe fractions must use a consistent mass- or mole-based convention. A binary phase diagram therefore relates composition and temperature to equilibrium phase assemblages; it does not say that every alloy consists of separate pure-metal grains.

In biomedical engineering, a biomaterial is a material selected or designed to interact with a biological system for a medical purpose. Its defining feature is this intended interaction, rather than whether it originated in an organism. A synthetic polymer, a metal or a ceramic can therefore be a biomaterial; natural collagen can also be processed for such a use. The biomedical meaning should be distinguished from the broader use of “bio” to mean material obtained from biomass.^[ref]

A biomaterial has both a material function and a biological environment. A load-bearing component must transmit forces without unacceptable deformation, but its surface also contacts fluid, proteins and biological cells. Biocompatibility consequently concerns an appropriate host response for a particular application; it is not a universal label that guarantees identical behavior at every site or for every exposure duration.^[ref]

An illuminating historical example is the 1971 work of L. L. Hench and colleagues on a bone-bonding glass-ceramic. They compared laboratory measurements of glass-ceramic solubility and interfacial hydroxyapatite crystallization with histology and ultrastructure observations around implants in rat femurs. The important question was how the material–bone interface developed, rather than merely whether the bulk ceramic was strong.^[ref]

To separate bulk behavior from an interface effect in a model experiment, one could compare specimens with identical dimensions and bulk Young's modulus but different surface treatments, while holding the cell culture conditions fixed. Measure both the mechanical response and cell adhesion, instead of substituting one for the other. Conversely, changing specimen thickness while retaining the same surface can change bending resistance without changing the nominal surface chemistry. These controlled comparisons show why evaluating a biomaterial requires specifying the material, its geometry, its interface and the biological setting together.

Bismuth is the chemical element with atomic number 83 and symbol $\mathrm{Bi}$. It is a metal. The $+3$ oxidation state is common. Natural bismuth is dominated by the extremely long-lived radioactive isotope bismuth-209, showing that everyday apparent stability and strict nuclear stability are not identical.^[ref]

Borazine dearomatization interrupts the planar pi system, for example when a nucleophile makes one boron tetrahedral. In a metal pi complex, this can change ring hapticity and produce a charged ligand with a different donor count.

Cadmium is the chemical element with atomic number 48 and symbol $\mathrm{Cd}$. It is a metal. Its common oxidation state is $+2$. Compounds such as cadmium sulfide have optical and semiconductor properties that differ from elemental cadmium, illustrating the need to distinguish an element from a specific material containing it.^[ref]

For a series of comparable metal carbonyls, greater metal-to-CO pi backbonding populates CO antibonding orbitals, weakens its internal bond and lowers its infrared stretching frequency. Coupled normal modes and changing geometry must be considered when comparing observed bands.

A hydrosilylation cycle involving Si–H oxidative addition, alkene insertion into the metal–hydride bond, and C–Si reductive elimination. This defines the conventional version; insertion into a metal–silyl bond describes a modified alternative.

A complex in which a ligand binds the same metal through at least two distinct donor atoms, closing a coordination ring.

Treatment using a molecule that binds a metal through several coordinating groups, changing its distribution or elimination. The relevant metal and clinical circumstances matter: chemical binding alone does not demonstrate benefit for every form of poisoning.

A chemical shift in photoelectron spectroscopy is a difference in binding energy for the same kind of core electron in different chemical surroundings, using comparable energy references. Identifying a chemical element assigns its family of lines; resolving chemical shifts within that family asks how its chemical atoms are bonded. For example, distinguishing a metal from its chemically modified surface requires more than detecting that element in both places.

The removal energy compares the initial electronic state with the state left after emission. Redistribution of the remaining electrons changes that final state's energy; a measured shift therefore includes relaxation as well as initial bonding effects.^[ref]

This makes chemical shift in photoelectron spectroscopy useful but conditional. Compare the same electron shell, the same photoelectron binding energy reference, and compatible sample conditions. Agreement with a chemically appropriate reference supports an assignment; a line position by itself need not uniquely determine an oxidation state. An unresolved sum of two chemical components can even have a centroid where neither component lies. The following Gaussian mixture distribution shows exactly how that happens without claiming a material identification.

A repeating structure in which metal centres are connected by bridging ligands. Its coordination connectivity can extend along one, two or three independent directions.

The set of ligands directly associated with a metal centre in the stated structural model. Distinguish primary donor bonds from secondary contacts and outer-sphere ions or lattice solvent.

The Cossee-Arlman mechanism propagates a polymer through alkene coordination followed by insertion into a metal–carbon bond. Repetition extends the metal-bound chain. Regioselectivity controls monomer connectivity; it does not by itself specify tacticity.

Separation of metal d-orbital energies by the electrostatic field of surrounding coordination ligands. An octahedral field puts the three $t_{2g}$ orbitals below the two $e_g$ orbitals.