FE4S4.

Article abstract of DOI:10.1021/ja00363a013

The series left bracket Fe//4S//4(SC//6H//4-o-X)//4 right bracket **2** minus with X equals NH//2 OMe, OH, and SMe was prepared in order to examine the possible formation of five-coordinate Fe sites in cubane-type clusters with the biologically significant left bracket Fe//4S//4 right bracket **2** plus core oxidation level. The compound (Et//4N)//2 crystallizes in monoclinic space group P2//1/c with a equals 11. 786 angstrom, b equals 20. 701 Angstrom, c equals 20. 536 Angstrom, beta equals 94. 42 (2) degree and Z equals 4. The cluster contains three conventional tetrahedral FeS//4 sites and one distorted trigonal-bipyramidal FeS//4O site, in which the o-HOC//6H//4S** minus ligand forms a chelate ring with the bond distances Fe-S equals 2. 313 (3) A and Fe-O(H) equals 2. 318 (5) A. The former bond, being only 0. 035 A longer than the mean of three other terminal Fe-S distances, represents a primary interaction; the Fe-OH bond distance reflects a weaker, secondary interaction. In the solid state the **5**7Fe Moessbauer spectrum of 1 is a single quadrupole doublet, reflects a weaker, secondary interaction.