Synthesis and structures of the first triiodoarsenate(III) anion, EtAsI₃^{鈭?/sup>, and zwitterions, (HPy)₂As₂I₆}

详细信息    查看全文

• 作者：Igor Yu. Ilyin ; Sergey N. Konchenko ; Alex ; er V. Virovets ; Natalia V. Kuratieva ; Nikolay A. Pushkarevsky
• 关键词：Iodoarsenates(III) ; Crystal structure ; Intermolecular interactions ; Ligand lability
• 刊名：Polyhedron
• 出版年：8 January, 2014
• 年：2014
• 卷：67
• 期：Complete
• 页码：115-121
• 全文大小：918 K

文摘

The first examples of organotriiodoarsenates(III) in the form of zwitterions, (3-HPy)₂As₂I₆ and (4-HPy)₂As₂I₆, have been obtained from aqueous solutions, and their structures have been established by XRD. The dimeric molecules in the crystals are built from two square pyramidal (HPy)AsI₄ units joined by 2 bridging I atoms. The crystal packing of both compounds is largely defined by interlayer As鈰疘 contacts, which fulfill the coordination sphere of the As atoms to 6 in the 4-HPy isomer and result in its characteristic red colour and lower solubility. These intermolecular interactions in the crystal structure can be suppressed by the inclusion of a solvent, showing them to be not very strong. The intramolecular bonding via the two bridging I atoms was proven to be rather weak as well, by the formation of the salt [Et₄N][EtAsI₃] with a monomeric triiodoarsenate(III) anion from acetonitrile solution. In the closely related compound p-H₂NC₆H₄AsI₂路HI, one iodide can be substituted for the OTs^{鈭?/sup> anion to give [p-H₃NC₆H₄AsI₂]OTs, showing the iodide belongs to the outer sphere rather than being coordinatively bound to the As atom. The lengths of the trans-I-As-I bonds in the determined structures can be formalized by a semi-empirical modified Pauling equation, which relates them to the bond order, taking into account the antibonding influence of the 4s orbital of the As atom.}