MACROCYCLIC COORDINATION COMPOUNDS by DESIGN: CRYSTAL STRUCTURES of M(18-Crown-6)+ (M+= NH4+, Tl+, Rb+, Cs+) WITH CENTROSYMMETRIC ANIONS H{ONC(CN)COPh}2-, AuCl4-)
V.V. Ponomareva1, J. A. Manskaya1, K.V.Domasevitch1, V.N.Kokozay1, Joachim Sieler2
1Department of Inorganic Chemistry,
Kiev University; Volodimirska St. 64, Kiev 252033, Ukraine,
E-mail: vera@anorgchemie.univ.kiev.ua
2 Institut für Anorganische Chemie,
Universität Leipzig; Linnéstraße 3, D-04103 Leipzig, Germany
The symmetry of counter anion can influence on the geometry of [M(18-Crown-6)]+ (A) moiety. It can be supposed that single charged centrosymmetric organic (H(L)2-, and complex anions AuCl4-, SbCl6-, (B) are bound to the metal atoms of the fragments [M(18-Crown-6)]+ on both sides of the crown ether plane to produce a one dimensional polymeric structure: -B-[-A-B-]-A-. In this case relatively large cations (Tl+, Rb+, Cs+) can be located exactly in the center of small crown-ether cavity. In this context the corresponding crystal structure of the ammonium cation is of special interest seeing NH4+ doesn't possess spherical symmetry in distinction from metal cations . Herein we report the results of X-Ray investigation of the complexes M(18-Crown-6)L (M+= NH4+, Tl+, Rb+, Cs+; L- = H{ONC(CN)COPh}2- (H{X}2-) , AuCl4-). We have found that the structure of the coordination compound M(18-Crown-6)(AuCl4) with complex centrosymmetric anion demonstrates an example of almost perfect fit of the rubidium atom inside the crown ether cavity. In this structure Rb+ cation was found to be equally disordered above and below the crown ether plane and deviated from it only by 0.276(2) Å, that is essentially less then observed earlier it for Rb(18-Crown-6) complexes. The structures of the coordination compounds of Thallium, Rubidium and Ammonium with single charged centrosymmetric organic anion H{X}2- are isostructural. Central atoms located exactly in the center of relatively small cavity of the macrocycle and occupy the center of inversion. There are a first unprecedented examples of perfect fit of the large Thallium, Rubidium and noncentrosymmetric Ammonium cations inside the crown ether cavity. Crystal structure of the Caesium complex is significantly differ from they and represent the complex with typical "sunrise coordination". Central atom is situated 1.492(3) Å above the mean crown ether plane. Thus we can conclude that the nature of counter ions can influence on the geometry of macrocyclic coordination compounds. The single charged centrosymmetric anions (H{ONC(CN)COPh}2- and AuCl4- as examples) can promote the formation of the centrosymmetric fragments [M(18-Crown-6)]+ (1) Domasevitch, K.V.; Skopenko, V.V.; Sieler, J. Inorg. Chim. Acta 1996, 249/2, 151. Yours sincerely, Vera Ponomareva Dr. V.V.Ponomareva, Department of Chemistry, Shevchenko University 252033 Kyiv, UKRAINE e-mail: vera@anorgchemie.univ.kiev.ua