Joe W. Vaughn

Fluoro-diamine complexes of chromium(III)

C. D. E. F. G. H. Introduction ._._ _._______..___ __ __._ __.________._._._._._____ 265 Syntheticmethods .__._.__..._._._.__ . . . . . . . . . . .._._...__.._____ 266 (i) Direct reaction of CrFs-3.5 Hz0 and the anhydrous diamine. AA . _ _ . _ _ _ _ _ _ 266 (ii) Reactions in buffered solutions . _ . _ . _ . _ _ . . . . . _ . . . _ _ _ . _ . _ _ _ . _ _ _ _ _ 269 (iii) Reactionsin2-methoxyethanol . _. _. _. . . . . . . _. _. _ _ _. _ _ _ _ _ _ _ _ _ _. _ _ 269 (iv) Aoationreactionsinmethylalcohol. _._ ._. _. __. . __ __ .___. _ _ _ _. __ _ _ 270 (v) Dehydrationreactions . _. _. _. _. _ _ _. . _. . . . . . . . . _. _. _. . . . _ _ _ _ _. _ 271 (vi) Substitution reactions in a coordinating solvent _ . _ _ _ . _ _ . _ _ _ _ _ _ . . _ _ _ _ _ _ 271 Electronicspectra. _. _. . . . -. . . . . _. _. _ _. _. . . . . . _. . _. _. _. _. _ _ _ _ _ _ _. 272 Polarizedspectra . _ _. _ _ _. . _. . . . . . . . . . . . . _. . . . . . _. _. _. . . . _. _. _ _. _ 273 Kineticstudies .__._._._. _._._.__ 279 1,3-Propanediamine complexes _ 1 _ . _ . . _ . . . . . _ . _ . _ . . _ _ . _ . _ . . _ . _ . _ . _ . . 281 Photochemistry _ _._._._._._...___ _ _ _....._ _._..__........___._. 287 X-raystructuralstudics . . . ..__._. _ .__. _._._ ___.__ ___ 291 References . . . . . . . . . . . . . . . _ . . _ . _ . . _ _ . _ . _ . _ . _ . _ . , . _ . . _ . . . _ . _ . _ . _ _ _ 292

Fluoro-containing Complexes of Cr(III). A Brief Review of Some Preparative Methods and Reactivity

Abstract INTRODUCTION Recently there has been considerable interest in the kinetic behavior, photochemistry, single-crystal polarized electronic spectra and absolute configurations of fluoro-containing amine complexes of Cr(III). This brief review is concerned with the preparative chemistry and reactivity of complexes of the types [Cr(AA)2F2]+, [Cr(AA)2FX]+, [Cr(AA)(OH2)2F2]+, [Cr(AA) (BB)F2]+, [Cr(AA)(BB)FX]n+, and [Cr(AA)F4]−. (AA and BB are non-identical bidentate ligands.)

Structure oftrans-difluorobis(1,3-propanediamine)chromium(III) perchlorate, trans-[Cr(N2C3H10)2F2](C104)

The title compound is monoclinic,Mr=337.8,P21/c-C2h5 (No. 14),a=5.508(2),b=13.944(6),c=18.238(5) Å,β=95.99(3)°,V=1393.1(9) Å3,Z=4,Dx=1.61 g cm−3, λ(MoKα)=0.71073 Å,F(000)=660.0,μ=10.3 cm−1, finalR=0.051 for 2122 observed [I>3σ(I)] reflections. The two six-membered rings resulting from the coordination of the 1,3-propanediamine ligands to the chromium atom are in the chair conformation. The Cr-N and Cr-F distances average 2.085(4) and 1.876(3) Å, respectively.

The Preparation of Some Fluoro Containing Complexes of Chromium(iii)

Abstract A different synthetic approach for the preparation of the cis-bromofluorobis(ethylenediamine) and cis-chlorofluorobis(ethylenediamine)chromi-um(II1) cations is described. The complex cations were isolated as iodide salts and in the case of the chlorofluoro complex a perchlorate salt was also isolated.

A Rapid Synthesis of the Trans-Difluorodiaquoethylenediamine Chromium (III) Cation

Abstract A rapid synthesis of the trans-difluorodiaquoethylenediamine chromium (III) cation by acid hydrolysis of the tetrafluoroethyl-enediaminechromate (III) anion is described. The complex cation was isolated as a bromide or chloride salt.

Synthesis of complexes of the type [Cr en2FX]X☆

Recent i n t e r e s t in the chemistry o f the f l uo ro complexes of C r ( l l l ) has prompted us to repor t the synthesis o f a ser ies of new b is (e thy lened iamine) ch romium( l l l ) compounds. These complexes are apparent ly the f i r s t known examples of b is (e thy lenediamine) compounds which contain in add i t ion to the f l uo ro l igand another monodentate groun which is not the aquo or hydroxo l igand. The syn the t i c method is based on the e a r l i e r work of Dahme ( I ) who was able to prepare the [Cr en2(OH)FI ÷ ion in aqueous so l u t i on . This ion was used as the s t a r t i n q mater ia l since the f l uo ro l igand was already incorporated and the tedious job of i n se r t i ng the Fgroup could be avoided. The new complexes prenared in th i s i nves t i ga t i on a l l appear to invo lve a c~s arranqement of the F-X groups. This is supported by the u l t r a v i o l e t and v i s i b l e snectra of these complexes, and in one case by the reso lu t i on of a complex in to i t s on t i ca l ant ipodes.

Fluoro-containing complexes of chromium (III). II. Crystal structure oftrans-difluorodiaquo-ethylenediaminechromium(III) chloride

The results of an X-ray structure determination of one of the three possible chloride salts of [Cr(en) F2(OH2)2]+ show the two fluoro ligands to betrans to each other. The purple crystals are monoclinic in the space groupC2/c-C2h6, witha=11.409(3),b=9.319(2),c=10.260(3) Å,β=128.73(2)° andDc=1.73 g cm−3 forZ=4. Least-squares refinement based on 1341 independent observed reflections resulted in a finalR of 0.026. The molecule lies on a crystallographic two-fold axis, and the Cr-F, Cr-N, and Cr-O bond lengths are 1.885(1), 2.044(2), and 1.997(2) Å respectively. It is suggested that the ill-defined shoulder in the visible electronic spectrum of this complex is indicative of atrans dihalo geometry.