Reaction Of UCl4 with 3 or 4 mol equiv of Na(2)dddt (dddt = 5,6-dihydro-1,4-dithiine-2,3-dithiolate) in THF afforded the first example of a tetrakis(dithiolene) metal compound, [Na-4(THF)(8)U(dddt)(4)] (1). The red crystals of 1 are composed of infinite zigzag chains in which Na-2(mu-THF)(3) fragments ensure the linking of Na-2(THF)(5)U(dddt)(4) moieties; the uranium atom is in a dodecahedral environment of eight sulfur atoms. Treatment of UCl4 with 3 mol equiv of Na2dddt in pyridine gave a mixture of tris- and tetrakis(dithiolene) compounds. After addition of 18c6 (18-crown-6), only the tris(dithiolene) complex was obtained and crystallized as orange crystals of [Na(18c6)(py)(2)](2)[U(dddt)(3)]-2py (2-2py) in which the isolated [U(dddt)(3)](2-) anion adopts a slightly distorted trigonal prismatic configuration. A few red crystals of the unsolvated complex 2 and the trinuclear anionic compound [Na(18c6)(py)(2)](3)[Na{U(dddt)(3)}(2)] (3) were also obtained along with orange crystals of 2-2py. All the tris(dithiolene) compounds exhibit large folding of the dddt ligand and significant interaction between the C=C double bond and the metal center.