Rhodium(I)-Komplexe mit 2,5-Difurfurylpyrrol-Liganden / Rhodium(I) Complexes with 2,5-Difurfurylpyrrole Ligands

Abstract

<jats:title>Abstract</jats:title><jats:p> The 2.5-difurfurylpyrrole-O.N.O ligands 3a, b [R = CO<jats:sub>2</jats:sub>C<jats:sub>2</jats:sub>H<jats:sub>5</jats:sub> (a). COCH, (b)] are obtained by reaction of the furanes l a , b with the 2,5-bis(chloromethyl)pyrrole 2 in the presence of SnCl<jats:sub>4</jats:sub>. Proton abstraction from 3a, b with NaH affords the sodium salts 4a-Na and 4b-Na. Exchange of the chlorine bridges in [μ-ClRh(Diol)]<jats:sub>2</jats:sub> (5,5') (Diol = cyclooctadiene, norbornadiene) results in the formation of the 14-electron complexes (Diol)Rh(O.N.O) (6a,6'a). Addition of PPh<jats:sub>3</jats:sub>, yields the four-coordinated rhodium complexes (Diol)Rh(O.N.O)(PPh<jats:sub>3</jats:sub>) (7a,7'a). These compounds are also available in a reverse reaction sequence from 5,5', PPh<jats:sub>3</jats:sub>, and 4a-Na. The mononuclear rhodium complexes RhCl(Diol)(PPh<jats:sub>3</jats:sub>) (8,8') are isolated as intermediates. In 7a, 7'a the olefinic ligands are replaced by carbon monoxide to give the dicarbonyl rhodium complex (OC)<jats:sub>2</jats:sub>Rh(O.N.O)(PPh<jats:sub>3</jats:sub>) (9a) being detectable only in solution. The same result is achieved upon addition of CO to the compound (OC)Rh(O.N.O)(PPh,) (11a) which results bv the reaction of [μ-ClRh(CO)(PPh<jats:sub>3</jats:sub>)]<jats:sub>2</jats:sub> (10) with 4a-Na. Oxidative addition of CH<jats:sub>3</jats:sub>I or H<jats:sub>2</jats:sub> to 6a, 6 a, 7a, 7'a or 11a was not observed. <jats:sup>1</jats:sup>H and <jats:sup>31</jats:sup>P{<jats:sup>1</jats:sup>H} NMR investigations indicate that depending on the temperature the O.N.O ligand in the 14-electron rhodium complex 11a acts as tri- (11a-A), bi- (11a-B) and monodentate (IIa-C) ligands. respectively. 11a also reacts with PPh, to form the /ram-bis(phosphane)rhodium complex (PPh<jats:sub>3</jats:sub>)<jats:sub>2</jats:sub>Rh(CO)(O.N.O) (12a). 12a and the analogous complexes 12b and trans-(PMe<jats:sub>3</jats:sub>)<jats:sub>2</jats:sub>Rh(CO)(O,N.O) (14a) are obtained by action of ClRh(CO)L<jats:sub>2</jats:sub> (13) (L = PPh<jats:sub>3</jats:sub>. PMe<jats:sub>3</jats:sub>) on 4a-Na and 4b-Na, respectively. The methylene bridges in the O.N.O ligand 3a are not oxidized, neither in the non-complexed (3a) nor in the complexed (12a) state. According to an X-ray structural analysis 14a crystallizes in the monoclinic space group P2<jats:sub>1</jats:sub>/n with Z = 4. In 6a, 6'a, 7a, 7'a, 9a, 11a, 12a, b, and 14a the O.N.O ligand is always nitrogen bonded</jats:p>

Synthesis and structures of mononuclear 3,4-bis(trifluoromethyl)pyrrolyl complexes of Rh(i) and Ni(ii)

“…The synthesis of Rh-3,4-(CF 3 ) 2 -Pyr complexes from the lithium salt 3,4-(CF 3 ) 2 -PyrLi was unsuccessful, despite the fact that other groups had found success with this route using unsubstituted pyrroles. 8 However, the sodium salt, generated by reaction of 3,4-(CF 3 ) 2 -PyrH with NaH, and used in situ, was successfully used to synthesize the new complex [Rh(PMe 3 ) 3 (3,4- 16,17 There are numerous examples of Rh(I) complexes of the type [Rh(PMe 3 ) 3 X] including the previously described pyrazolate complex [Rh(PMe 3 ) 3 -(3,5-(CF 3 ) 2 -Pz)] 18 but 1 appears to be the first reported pyrrolyl compound with this general formula.…”

“…All other spectroscopic data were in accord with previously published values. 17 [trans-Ni(PMe 3 ) 2 (3,4-(CF 3 ) 2 -Pyr)(CH 3 )] (3). The treatment of 2 with two equivalents of 3,4-(CF 3 ) 2 -PyrH at −10 °C in toluene followed by a slow warming, heating to reflux and reaction time of 8 hours resulted in a yellow solution of 3.…”