| Names | |
|---|---|
| Other names Californium borate | |
| Identifiers | |
3D model (JSmol) | |
| |
| |
| Properties | |
| Cf[B6O8(OH)5] | |
| Molar mass | 526.90 g/mol[1] |
| Appearance | pale green plates |
| Density | 3.842 g/cm3, solid |
| Structure | |
| monoclinic[1] | |
| C2/c | |
a = 6.849 Å,b = 18.809 Å,c = 101.36 Å α = 90°, β = 124.72°, γ = 90° | |
Lattice volume (V) | 910.9 |
Formula units (Z) | 4 |
| 8 coordinatesquare antiprism | |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Californium polyborate is a covalent compound with formula Cf[B6O8(OH)5]. In this compound thecalifornium is in a +3 oxidation state. This compound is the highest atomic number borate with a visible solid phase. Heavier elements than californium decay too fast to make macroscopic amounts of solid crystals.[1]
Californium polyborate is unusual in that californium is covalently bound to the borate. Californium was expected to resemblelanthanide elements in being highly ionic. Thepolyborate anion is polarisable and flexible.[2] The 5f, 6d, 7s, and 7p orbitals of californium are all involved on the bonding.[2] Most valence electrons are in the 5f orbital, and a significant fraction (2⁄3) in the 6d orbital, and smaller fractions of one electron are in the 7s and 7p orbitals.[1]
Californium(III) polyborate can be made by autoclaving acalifornium(III) chloride solution in water with excess boric acid for a week at 240°C. This is then cooled slowly to room temperature for another three days. Water dissolves excess boric acid to leave insoluble crystals of the borate.[1]
The californium(III) polyborate solid undergoes a green fluorescence of 525 nm with ultraviolet light of wavelengths 365 or 420 nm.[1] There is also an invisible near infrared fluorescence at 1020 nm induced by green light at 546 nm.[1]
Californium polyborate is dangerous because of the radioactivity of californium and its decay daughtercurium. Between them these elements emitα particles,gamma rays andneutrons.[1]
