The reactions of the diaryl-diselenides (p-FC6H4)2Se2 and (p-ClC6H4)2Se2 with diiodine have been investigated. Species of stoichiometry âRSeIâ are formed when the ratio employed is 1â:â1. The solid-state structure of â(p-FC6H4)SeIâ has been determined, and shown to be a charge-transfer (CT) adduct, (p-FC6H4)2Se2I2, where the SeâSe bond is retained and the diiodine molecule interacts with only one of the selenium atoms. The SeâI bond in (p-FC6H4)2Se2I2 is 2.9835(12) Ã
, which is typical for a (10-I-2) SeâIâI CT system. When diiodine is reacted in a 3â:â1 ratio with (p-XC6H4)2Se2 (X = F, Cl) species of stoichiometry âRSeI3â are formed. The structure of â(p-ClC6H4)SeI3â reveals that this is not a selenium(IV) compound, but is better represented as a selenium(II) CT adduct, (p-ClC6H4)SeI·I2. The SeâI bond to the diiodine molecule is typical in magnitude for a CT adduct, SeâI: 2.8672(5) Ã
, whereas the other SeâI bond is much shorter, SeâI: 2.5590(6) Ã
, and is a genuine example of a rarely observed covalent SeâI bond, which appears to be stabilised by a weak Seâ¯I interaction from a neighbouring iodine atom. The reaction of (p-ClC6H4)SeI with Ph3P results in the formation of a CT adduct, Ph3PSe(p-ClC6H4)I, which has a T-shaped geometry at selenium (10-Se-3). By contrast, the reaction of (p-FC6H4)SeI with Ph3P does not form an adduct, but results in the formation of Ph3PI2 and (p-FC6H4)2Se2.
研究了二芳基二
硒化物 (p-FC6H4)2Se2 和 (p-ClC6H4)2Se2 与二
碘的反应。当采用的比例为 1â:â1时,会形成
化学计量为âRSeIâ的物种。(p-FC6H4)SeIâ的固态结构已经确定,并被证明是一种电荷转移(CT)加合物,即(p-FC6H4)2Se2I2,其中保留了Se键,二
碘分子只与其中一个
硒原子发生作用。(p-FC6H4)2Se2I2 中的 SeâI 键为 2.9835(12) Ã,是典型的 (10-I-2) SeâIâI CT 系统。当二
碘与(p-XC6H4)2Se2(X = F、Cl)以 3â:â1 的比例反应时,会形成
化学式为âRSeI3â的物质。(p-ClC6H4)SeI3â的结构表明,这不是一种
硒(IV)化合物,而是一种
硒(II)CT加合物,即(p-ClC6H4)SeIÂ-I2。与二
碘分子相连的 SeâI 键是典型的 CT 加合物,SeâI:2.8672(5) Ã,而另一个 SeâI 键要短得多,SeâI:2.5590(6) Ã,是一个很少观察到的共价 SeâI 键的真实例子,它似乎通过邻近
碘原子的微弱 Seâ¯I 作用而得到稳定。(p-ClC6H4)SeI 与 Ph3P 反应会形成 CT 加合物 Ph3PSe(p-ClC6H4)I,该加合物在
硒(10-Se-3)处呈 T 型几何结构。相比之下,(p-FC6H4)SeI 与 Ph3P 反应不会形成加合物,但会形成 Ph3
PI2 和 (p-FC6H4)2Se2。