Isomers of octahedral complexes with nonbranching ligands

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ISOMERS OF OCTAHEDRAL COMPLEXES WITH NONBRANCHING LIGANDS

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RUSSELL I.TRIMBLE, JR. University of Rochester, Rochester, New York

ALTHonm interest in the field of metal complexes has risen greatly in the past few years, there is not available O ~ L IO W ~YCIY-E.OPTICILU. m w . any tabulation of the various ways in which ligands can lCr,YL, T,ons- A SOSllBLE A be distributed about an octahedral frame.' The purpose of this paper is to present such a tabulation for nonbranching ligands. Nonbranching ligands are those ligands in which each coordinating group is connected to two other coordinating groups only, except for the two terminal groups, which are connected to only one other coordinating group. Complexes that include branched-chain ligands (such as ethylenediaminetetraacetic acid), or which are polynuclear, are not considered because of their tremendously increased geometrical complexity. Isomerism within the ligand molecule (or ion) is not taken into account because such isomerism does not arise from the structure of the comC(6-u ~ ~ M z - A B plex. Within these limits the tabulation of structures is believed to be complete. The isomers were determined from drawings of the arrangements possible with various types of ligands, due rronr- u A care being taken to eliminate duplicate structures and Fiwrs 1 mirror images. In a few doubtful cases models were 'Note that the structural denimations in the third oolumn of Tablcr 2 used. It was found possible to calculate the number of and 3 .we not sufficient if taken from the context of the tablaa. isomers to be expected only for the case of a complex with six differentmonodentate ligands. TABLE 1 The information is presented in three Structures Containing Monodentate Ligands Only tables. Table 1 lists the various strucFonnlllo Blructzlre tures possible with only monodentate * uo ligands. Table 2 lists the structures * usv possible with only one species of polydenum cis-v / trans-v u,vw cis-vw / trans-vw tate ligand, and Table 3 lists the strucuavs fac-u / mer-u tures containing more than one species of U ~ W me?-u !is-v / mer-u trans-v / fac-u me?-u trans-vw (wx, vx) / fac-u polydentate ligand. Each entry in these UJt~ans-utrans-v trans-w / cis-u cis-v cis-w uxvlwl tables represents a distinct structural cis-u eis-v t~ans-w/ cis-u cis-w trans-v entity which cannot be made congruent cis-v ci8-w tmns-u trans-u trans-v tmns-wx / cisu cis-v t~ans-wx umwx with anv other structure listed bv anv cis-u cis-wx t~ans-v/ cis-v cis-wx trans-u 1A partial tabulation of octs-coordinate irons-uw trans-vx / trans-ux trans-vw L. structures bas been published by MARCHI, trans-u t~ans-vw(vx, vy) / cis-u trans-vw (vx, vy, wx, WY, x).) u~vwxy trons-wx trankyz / trans-uy trans-w trons-xz uvwxyz transuv E., W. C. FERNELIUS, AND J. P. MCREYNOLDS, " " Wy xz/ vx " WE J. Am. Chern. Soc... 65.. 333-5 (1943). . . " " " wz " xy / , " VZ " WX I3

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