CRYSTAL AND MOLECULAR-STRUCTURE OF DICARBONYL(2,4-PENTANEDIIMINE)RHODIUM(I) TETRAFLUOROBORATE, A STRUCTURE HAVING EXTENDED RHODIUM-RHODIUM INTERACTIONS

The reaction of Rh2Cl2(CO)4 with 2, 4-pentanediiminium tetrafluoroborate in ethanol yields the planar Rh(I) complex [Rh(C5H10N2)(CO)2]BF4. The metallic gold luster of this complex suggested extended Rh(I)-Rh(I) interactions. Consequently, the crystal structure was determined in order to examine the nature of these interactions and compare them with those of closely related systems. The complex crystallizes in space group P21/c with [FORMULA OMMIETD]The observed and calculated densities, 1.85 and 1.86 g/cm3, respectively, correspond to Z=4. The structure was solved by standard heavy-atom methods and refined by full-matrix least-squares techniques to a conventional discrepancy factor of R =0.038 for 1722 observed reflections with [FORMULA OMMITED]cations were found to form weak dimers with a Rh(I)-Rh(I) distance of 3.271 (3) A, comparable to the distances found in a number of other Rh(I) complexes involving Rh(I)-Rh(I) extended interactions. These dimers are stacked in a columnar fashion along the.a axis to form a linear Rh(I) chain, with the Rh(I)-Rh(I) distance between dimers being 3.418 (3) A. The nonuniformity of the stacking appears to be the result of hydrogen-bonding interactions between the iminate hydrogen atoms and two of the fluorine atoms of the BF4- anions. © 1979, American Chemical Society. All rights reserved.