Free gadolinium ion (Gd³⁺)

Free gadolinium ion (Gd³⁺) is the trivalent, ionic form of the chemical element gadolinium, an f-block rare earth metal with atomic number 64[1][7]. It has a [Xe] 4f⁷ electron configuration and is uniquely paramagnetic due to its seven unpaired electrons, accounting for its utility when complexed (chelated) in MRI contrast agents[4][7]. In biological systems, free Gd³⁺ is considered highly toxic because it can replace calcium in various physiological processes, leading to disruption of cellular function and toxicity[3][9]. For this reason, gadolinium is always administered as a chelated complex in medicine; release of free Gd³⁺ from these complexes can cause severe toxicity, including nephrogenic systemic fibrosis, particularly in patients with renal impairment[7][9]. The free ion itself has no known beneficial biological function and is not a validated therapeutic target[3][7][9].

Other names

Gadolinium(III) ionGd3+gadolinium iongadolinium(3+) ion