Moscovium

History

The first successful synthesis of moscovium occurred in August 2003 at the Joint Institute for Nuclear Research in Dubna, Russia, by a joint team of Russian and American scientists. Headed by Russian nuclear physicist Yuri Oganessian, the team included American scientists from the Lawrence Livermore National Laboratory. On February 2, 2004, they reported in Physical Review C that bombarding americium-243 with calcium-48 ions produced four atoms of moscovium, which decayed by alpha-particle emission to nihonium in about 100 milliseconds.

The collaboration strengthened their claim by conducting chemical experiments on the final decay product 268Db, confirming its half-life and decay mode. However, in 2011, the IUPAC/IUPAP Joint Working Party did not recognize moscovium as discovered, citing insufficient confidence in distinguishing group 4 and group 5 elements and the lack of previously characterized decay properties. Two heavier isotopes, 289Mc and 290Mc, were discovered in 2009–2010 as daughters of tennessine isotopes, with 289Mc later directly synthesized and confirmed.

Predicted properties

Very few properties of moscovium or its compounds have been measured due to its extremely limited and expensive production and rapid decay. Moscovium is expected to lie within an island of stability centered on copernicium and flerovium, where nuclei exclusively decay by alpha decay and possibly electron capture and beta decay due to high fission barriers. Although known isotopes lack enough neutrons for the island, heavier isotopes are generally longer-lived.

The hypothetical isotope 291Mc, with one more neutron than 290Mc, could be synthesized as the daughter of 295Ts from the reaction 249Bk(48Ca,2n)295Ts, potentially having a half-life of several seconds and a significant electron capture or positron emission decay mode, leading to 291Cn in the island's center with a half-life of about 1200 years. Drawbacks include a low expected cross section for 295Ts production and unexplored decay properties near beta stability.

Heavy isotopes from 291Mc to 294Mc might also be produced via charged-particle evaporation in reactions with curium isotopes. The isotope 286Mc was found in 2021 at Dubna in the 243Am(48Ca,5n)286Mc reaction, decaying into known 282Nh. Undiscovered light isotopes 284Mc and 285Mc could be synthesized in the 241Am+48Ca reaction, while 282Mc and 283Mc might be produced in the 243Am+44Ca reaction, though with likely lower cross sections.

Experimental chemistry

The isotopes 288Mc, 289Mc, and 290Mc have half-lives long enough for chemical investigation. A 2024 experiment at the GSI, producing 288Mc via the 243Am+48Ca reaction, studied the adsorption of nihonium and moscovium on SiO2 and gold surfaces. The adsorption enthalpy of moscovium on SiO2 was determined experimentally, showing moscovium to be less reactive with SiO2 than bismuth but more reactive than copernicium and flerovium, due to relativistic stabilization of the 7p1/2 shell.