Editing Rutherfordium (section)

===Aqueous phase===
Rutherfordium is expected to have the electron configuration [Rn]5f<sup>14</sup> 6d<sup>2</sup> 7s<sup>2</sup> and therefore behave as the heavier homologue of [[hafnium]] in group 4 of the periodic table. It should therefore readily form a hydrated Rf<sup>4+</sup> ion in strong acid solution and should readily form complexes in [[hydrochloric acid]], [[hydrobromic acid|hydrobromic]] or [[hydrofluoric acid]] solutions.<ref name="Kratz03" />

The most conclusive aqueous chemistry studies of rutherfordium have been performed by the Japanese team at [[Japan Atomic Energy Research Institute]] using the isotope <sup>261m</sup>Rf. Extraction experiments from hydrochloric acid solutions using isotopes of rutherfordium, hafnium, zirconium, as well as the pseudo-group 4 element [[thorium]] have proved a non-actinide behavior for rutherfordium. A comparison with its lighter homologues placed rutherfordium firmly in group 4 and indicated the formation of a hexachlororutherfordate complex in chloride solutions, in a manner similar to hafnium and zirconium.<ref name="Kratz03" /><ref>{{cite journal | doi=10.1524/ract.2005.93.9-10.519 | title=Chemical studies on rutherfordium (Rf) at JAERI | date=2005 | last1=Nagame | first1=Y. | journal=Radiochimica Acta | volume=93 | issue=9–10_2005 | page=519 | url=http://wwwsoc.nii.ac.jp/jnrs/paper/JN62/jn6202.pdf | last2=Tsukada | first2=K. | last3=Asai | first3=M. | last4=Toyoshima | first4=A. | last5=Akiyama | first5=K. | last6=Ishii | first6=Y. | last7=Kaneko-Sato | first7=T. | last8=Hirata | first8=M. | last9=Nishinaka | first9=I. | last10=Ichikawa | first10=S. | last11=Haba | first11=H. | last12=Enomoto | first12=Shuichi | s2cid=96299943 | display-authors=1 | archive-url=https://web.archive.org/web/20080528125634/http://wwwsoc.nii.ac.jp/jnrs/paper/JN62/jn6202.pdf | archive-date=2008-05-28 }}</ref>

:{{chem|261m|Rf|4+}} + 6 {{chem|Cl|-}} → {{chem|[|<sup>261m</sup>RfCl|6|]|2-}}

Very similar results were observed in hydrofluoric acid solutions. Differences in the extraction curves were interpreted as a weaker affinity for fluoride ion and the formation of the hexafluororutherfordate ion, whereas hafnium and zirconium ions complex seven or eight fluoride ions at the concentrations used:<ref name="Kratz03" />

:{{chem|261m|Rf|4+}} + 6 {{chem|F|-}} → {{chem|[|<sup>261m</sup>RfF|6|]|2-}}

Experiments performed in mixed sulfuric and nitric acid solutions shows that rutherfordium has a much weaker affinity towards forming sulfate complexes than hafnium. This result is in agreement with predictions, which expect rutherfordium complexes to be less stable than those of zirconium and hafnium because of a smaller ionic contribution to the bonding. This arises because rutherfordium has a larger ionic radius (76&nbsp;pm) than zirconium (71&nbsp;pm) and hafnium (72&nbsp;pm), and also because of relativistic stabilisation of the 7s orbital and destabilisation and spin–orbit splitting of the 6d orbitals.<ref>{{cite journal |last1=Li |first1=Z. J. |last2=Toyoshima |first2=A. |first3=M. |last3=Asai |first4=K. |last4=Tsukada |first5=T. K. |last5=Sato |first6=N. |last6=Sato |first7=T. |last7=Kikuchi |first8=Y. |last8=Nagame |first9=M. |last9=Schädel |first10=V. |last10=Pershina |first11=X. H. |last11=Liang |first12=Y. |last12=Kasamatsu |first13=Y. |last13=Komori |first14=K. |last14=Ooe |first15=A. |last15=Shinohara |first16=S. |last16=Goto |first17=H. |last17=Murayama |first18=M. |last18=Murakami |first19=H. |last19=Kudo |first20=H. |last20=Haba |first21=Y. |last21=Takeda |first22=M. |last22=Nishikawa |first23=A. |last23=Yokoyama |first24=S. |last24=Ikarashi |first25=K. |last25=Sueki |first26=K. |last26=Akiyama |first27=J. V. |last27=Kratz |display-authors=3 |date=2012 |title=Sulfate complexation of element 104, Rf, in H<sub>2</sub>SO<sub>4</sub>/HNO<sub>3</sub> mixed solution |url= |journal=Radiochimica Acta |volume=100 |issue=3 |pages=157–164 |doi=10.1524/ract.2012.1898 |s2cid=100852185 }}</ref>

Coprecipitation experiments performed in 2021 studied rutherfordium's behaviour in basic solution containing [[ammonia]] or [[sodium hydroxide]], using zirconium, hafnium, and thorium as comparisons. It was found that rutherfordium does not strongly coordinate with ammonia and instead coprecipitates out as a hydroxide, which is probably Rf(OH)<sub>4</sub>.<ref>{{cite journal |last1=Kasamatsu |first1=Yoshitaka |last2=Toyomura |first2=Keigo |first3=Hiromitsu |last3=Haba |first4=Takuya |last4=Yokokita |first5=Yudai |last5=Shigekawa |first6=Aiko |last6=Kino |first7=Yuki |last7=Yasuda |first8=Yukiko |last8=Komori |first9=Jumpei |last9=Kanaya |first10=Minghui |last10=Huang |first11=Masashi |last11=Murakami |first12=Hidetoshi |last12=Kikunaga |first13=Eisuke |last13=Watanabe |first14=Takashi |last14=Yoshimura |first15=Kosuke |last15=Morita |first16=Toshiaki |last16=Mitsugashira |first17=Koichi |last17=Takamiya |first18=Tsutomu |last18=Ohtsuki |first19=Atsushi |last19=Shinohara |display-authors=3 |date=2021 |title=Co-precipitation behaviour of single atoms of rutherfordium in basic solutions |url= |journal=Nature Chemistry |volume=13 |issue= 3|pages=226–230 |doi=10.1038/s41557-020-00634-6 |pmid=33589784 |bibcode=2021NatCh..13..226K |s2cid=231931604 }}</ref>