EFFECT OF DIVERSE LIGANDS ON THE COURSE OF A MOLECULES-TO-SOLIDS PROCESS AND PROPERTIES OF ITS INTERMEDIATES

We have been studying chemical processes that use discrete molecular r eagents to form extended solid inorganic materials. The goals of this program have been to determine how best to design and implement these molecular precursor reactions and to discover what chemical intermedia tes lie on the molecules-to-solids paths. In this manuscript we report studies of the reactions of the low-valent iron complex Fe(C8H8)2 wit h low-valent tellurium compounds of the form TePR3 (R = various hydroc arbon groups) that lead ultimately to the exclusively inorganic extend ed solid compounds Fe(x)Te(y). We have found four Fe/Te cluster types that are chemical intermediates in this process: 6,3;(dmpe)2FeTe2,4;(d epe)2FeTe2,5;Fe4Te6(dmpe)4,6. (Here (i)Pr = CHMe2, dmpe = Me2PCH2CH2PM e2, and depe = Et2PCH2CH2PEt2.) The different clusters form when diffe rent supporting phosphine ligands are employed. We report the synthese s, structures, and properties of these intermediates and the compariso ns and contrasts between these molecular intermediates and the extende d solid products. We note that when larger ligands are used smaller cl usters are formed. We also note what features of the molecular structu res lead to ferromagnetic versus antiferromagnetic coupling of the dis tinct Fe centers. We have determined the structures of the following m aterials crystallographically: 2 (C36Hg4Fe4Te4P4; tetragonal, P421cBAR ; a = 14.0469(7) angstrom, c = 13.5418(9) angstrom; z = 2); 3 (C18H54F e6TeBP6; trigonal, R3BAR; a = 11.859(2) angstrom, c = 26.994(5) angstr om; Z = 3); dmpe.2Te (C6Hl6Te2P2; monoclinic, P2(1)/c; a = 6.0890(4) a ngstrom, b = 10.7934(7) angstrom, c = 9.8200(5) angstrom, beta = 104.6 3(7)-degrees; Z = 2); 5 (C20H48FeTe2P4; orthorhombic, Pbnn; a = 10.997 (3) angstrom, b = 14.157(3) angstrom, c = 18.345(4) angstrom; Z = 4); 6 (C24H64Fe4Te6P8; orthorhombic, Abaa; a = 12.056(3) angstrom, b = 17. 725(5) angstrom, c = 21.403(8) angstrom; Z = 4).