Barnes Nicholas A, Godfrey Stephen M, Halton Ruth T A, Mushtaq Imrana, Pritchard Robin G
School of Chemistry, The University of Manchester, Manchester, PO Box 88, UK.
Dalton Trans. 2006 Oct 28(40):4795-804. doi: 10.1039/b608453b. Epub 2006 Aug 3.
The reaction of (Ph(2)Se(2)I(2))(2) with a wide variety of tertiary phosphines possessing different steric and electronic properties has been studied, leading in most cases to R(3)PSe(Ph)I adducts; [R(3)P = (p-CH(3)C(6)H(4))(3)P (1), (m-CH(3)C(6)H(4))(3)P (2), (o-OCH(3)C(6)H(4))(3)P (4), Ph(2)MeP (6), Me(2)PhP (7), Me(3)P (8), Cy(3)P (9)]. All of the products formed were characterised by elemental analysis, Raman and multinuclear NMR spectroscopy. Both steric and electronic factors are important in determining the structural motif (CT vs. ionic) observed in the solid-state. In general, highly basic phosphines result in a lengthening of the Se-I interaction, and a preference for an ionic structure. The reaction with (o-CH(3)C(6)H(4))(3)P does not yield a stable R(3)PSe(Ph)I adduct, and instead (o-CH(3)C(6)H(4))(3)PI(2) (3) is formed. The unusually long P-I bond, [2.5523(12) A], and short I-I bond, [3.0724(4) A], exhibited by is a result of the high steric requirements of this phosphine. The similarly bulky (o-SCH(3)C(6)H(4))(3)P yields a mixture of (o-SCH(3)C(6)H(4))(3)PSe(Ph)I (5a) and [(o-SCH(3)C(6)H(4))(3)PSePh]I(3) (5b). The crystal structures of (m-CH(3)C(6)H(4))(3)PSe(Ph)I, 2, (o-CH(3)C(6)H(4))(3)PI(2), 3, [(o-OCH(3)C(6)H(4))(3)PSePh]I.CH(2)Cl(2), 4, [(o-SCH(3)C(6)H(4))(3)PSePh]I(3), 5b, two pseudo-polymorphs of Ph(2)MePSe(Ph)I, 6a/6b, and Me(3)PSe(Ph)I.CH(2)Cl(2), 8, are reported. The R(3)PSe(Ph)I adducts formed exhibit one of four types of behaviour. Type I products, (such as 2) are CT in the solid-state and display fluxionality in solution. Type II products (such as 6a/6b) lie close to the CT/ionic structural borderline, displaying long Se-I bonds, and are more appropriately classified as [R(3)PSePh] (acceptor)/I(-) (donor) CT complexes. Type II complexes ionise in solution to [R(3)PSePh]I. Type III products, such as 8, are ionic in solution, but frequently show cation-anion, or cation-solvent interactions in the solid-state, although these interactions are weak and the linear P-Se-I motif is lost. Type IV products (such as 4) are ionic and feature bulky phosphines. They display no short cation-anion interactions in the solid-state.
研究了(Ph(2)Se(2)I(2))(2)与多种具有不同空间和电子性质的叔膦的反应，在大多数情况下生成R(3)PSe(Ph)I加合物；[R(3)P = (p-CH(3)C(6)H(4))(3)P (1)、(m-CH(3)C(6)H(4))(3)P (2)、(o-OCH(3)C(6)H(4))(3)P (4)、Ph(2)MeP (6)、Me(2)PhP (7)、Me(3)P (8)、Cy(3)P (9)]。所有生成的产物均通过元素分析、拉曼光谱和多核核磁共振光谱进行了表征。空间和电子因素在决定固态中观察到的结构模式（电荷转移与离子型）方面都很重要。一般来说，高碱性的膦会导致Se-I相互作用延长，并倾向于形成离子结构。与(o-CH(3)C(6)H(4))(3)P的反应不会生成稳定的R(3)PSe(Ph)I加合物，而是生成(o-CH(3)C(6)H(4))(3)PI(2) (3)。该膦的空间需求很高，导致其具有异常长的P-I键[2.5523(12) Å]和短的I-I键[3.0724(4) Å]。同样体积较大的(o-SCH(3)C(6)H(4))(3)P生成了(o-SCH(3)C(6)H(4))(3)PSe(Ph)I (5a)和[(o-SCH(3)C(6)H(4))(3)PSePh]I(3) (5b)的混合物。报道了(m-CH(3)C(6)H(4))(3)PSe(Ph)I（2）、(o-CH(3)C(6)H(4))(3)PI(2)（3）、[(o-OCH(3)C(6)H(4))(3)PSePh]I·CH(2)Cl(2)（4）、[(o-SCH(3)C(6)H(4))(3)PSePh]I(3)（5b）、Ph(2)MePSe(Ph)I的两种假多晶型（6a/6b）以及Me(3)PSe(Ph)I·CH(2)Cl(2)（8）的晶体结构。生成的R(3)PSe(Ph)I加合物表现出四种行为类型之一。I型产物（如2）在固态时为电荷转移型，在溶液中表现出分子流动性。II型产物（如6a/6b）接近电荷转移/离子结构边界，具有长的Se-I键，更适合归类为[R(3)PSePh]（受体）/I(-)（供体）电荷转移配合物。II型配合物在溶液中会离子化为[R(3)PSePh]I。III型产物（如8）在溶液中为离子型，但在固态时经常表现出阳离子-阴离子或阳离子-溶剂相互作用，尽管这些相互作用较弱且线性的P-Se-I结构单元会消失。IV型产物（如4）为离子型且具有体积较大的膦。它们在固态时不显示短的阳离子-阴离子相互作用。
