RHODIUM(I) ANION CARBONYL(MALEONITRILEDITHIOLATO)(TRIETHYLPHOSPHINE)RHODATE(I) AND ACYL COMPLEXES DERIVED FROM ITS REACTION WITH ALKYL-HALIDES

The Rh(I) complex [Rh(CO)(PEt3)(mnt)]- generated in situ by the addition of PEt3 to [Rh(CO)2(mnt)- reacts with various alkyl halides R-X (X=I, R=Me, Et, n-Pr, n-Bu, n-C10H21, i-Pr, i-Bu; X=Br, R=Et, n-Pr, n-Bu, Bz, allyl, propargyl; X=CI, R=allyl) in the presence of excess phosphine to form a series of stable neutral Rh(III) acyl species of formula Rh(COR)(PEt3)2(mnt). These complexes have been characterized by IR and 1H NMR spectroscopy, and the structure of a representative member of the series (R=n-Pr) has been determined by single-crystal X-ray diffraction methods. The structure determination of Rh(CO-n-Pr)(PEt3)2(mnt) shows that the complex crystallizes in space group D2h15-Pbca in a cell of dimensions a=20.47 (4) Å, b=13.61 (3) Å, and c=18.44 (4) Å with eight molecules per unit cell (pexpti=1.40 (2) g/cm3; pcalcd=1.421 g/cm3). The coordination geometry of the complex is square pyramidal with the butanoyl group occupying the apical position at a distance of 2.002 (7) Å from the Rh(III) ion. The complex possesses nearly Cs symmetry in the solid state with the triethylphosphine conformations related by a noncrystallographic mirror. The Rh-S and Rh-P bond lengths average 2.320 and 2.348 Å, respectively. In the presence of excess PEt3, addition of perchloric acid to a solution of [Rh(CO)(PEt3)(mnt)]- results in the formation of the rhodium(III) hydride Rh(H)(CO)(PEt3)2(mnt). In contrast, the addition of acid to the rhodium(I) complex in acetonitrile in the presence of ethylene leads slowly to the formation of an acyl complex which is isolated as Rh(COEt)(PEt3)2(mnt) upon adding excess PEt3. © 1979, American Chemical Society. All rights reserved.