Divalent gold complex isolated for the first time in a pure form

According to textbook knowledge, the usual oxidation states of gold in compounds are +I and +III. The divalent form (+II), on the other hand, prefers to form polynuclear compounds or simply undergoes transformation into the mono- and trivalent forms. However, the elements next to gold in the periodic table are quite different in this respect. The ions of the coinage metals, copper(+II) and silver(+II), are usually present in divalent form and this is also the case for gold's neighbors to its lef