Synthesis and structural characterization of (THF)(3)Na{(SnC6H3-2,6-Trip(2))(2)} (Trip = C6H2-2,4,6-i-Pr-3): effects of cation-anion association on Sn-Sn multiple bonding

The synthesis and structural characterization of the contact ion-pair speci es (THF)(3)Na((SnC6H3-2,6-Trip(2))(2)) (1) are described. The compound 1 wa s synthesized by the reduction of sn(Cl)C6H3-2,6-Trip(2) with sodium anthra cenide in THF. Its UV-vis and EPR spectra are very similar to those previou sly reported for the solvent separated ion pairs [K(THF)(6)] [(SnC6H3-2,6-T rip(2))(2)] and [K(dibenzo-18-crown-6)(THF)(3)] [(SnC6H3-2,6-Trip(2))(2)]. The X-ray crystal structure of 1 reveals an Sn-Sn distance 2.8107(13)Angstr om and an Na-Sn bond length of 3.240(7)Angstrom with C-Sn-Sn angles of ca. 98 degrees. The Sn-Sn distance and tin geometry are very similar to those p reviously observed. These similarities lead to the conclusion that the Sn-S n bonding is affected only in a minor way by sodium coordination. Crystal d ata at 130 K with CuK alpha (lambda = 1.54178 Angstrom) radiation; 1, a = 2 2.142(5), b = 15.845(4), c = 23.425(7)Angstrom, beta = 107.83(2)degrees Z = 4, monoclinic, space group C2/c, R1 = 0.0615 for 4872 (I = 2 sigma(I)) dat a. (C) 1999 Elsevier Science S.A. All rights reserved.