CHLOROSELENOSELENATES AND POLYSELENOSELENATES(II) - SYNTHESIS, STRUCTURE, AND PROPERTIES OF [PH3(C2H4OH)P]2[SECL4].MECN, [PH4P]2[SE2CL6], AND [PH4P]2[SE(SE5)2]

By symproportionation of elemental selenium and SeCl4 in polar protic solvents the novel chloroselenates(+ II), [SeCl4]2- and [SeCl6]2-, could be stabilized; they were crystallized with voluminous organic cations. They were characterized from complete X-ray structure analysis. Yellow-orange [Ph3(C2H4OH)P]2[SeCl4].MeCN (space group P1BAR, a = 10.535(4), b = 12.204(5), c = 16.845(6) angstrom, alpha = 77.09(3)-degrees, beta = 76.40(3)-degrees, gamma = 82.75(3)-degrees at 140 K) contains in its crystal structure monomeric [SeCl4]2- anions with square-planar coordination of Se(+ II). The mean Se-Cl bond length is 2.441 angstrom. In yellow [Ph4P]2[Se2Cl6] (space group P1BAR, a = 10.269(3), b = 10.836(4), c = 10.872(3) angstrom, alpha = 80.26(3)-degrees, beta = 79.84(2)-degrees, gamma = 72.221(3)-degrees at 140 K) a dinuclear centrosymmetric [Se2Cl6]2- anion, also with square-planar coordinated Se(+ II), is observed. The average terminal