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Dinuclear Ti and Ti complexes supported by calix[4]arene ligands. Binding alkali-metal cations inside and outside the cavity of calix[4]arenes |
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| Authors: | F Albert Cotton Evgeny V Dikarev Carlos A Murillo Marina A Petrukhina |
| Affiliation: | a Laboratory for Molecular Structure and Bonding, Department of Chemistry, Texas A&M University, PO Box 30012, College Station, TX 77842-3012, USA b Department of Chemistry, State University of New York at Albany, Albany, NY 12222, USA c Department of Chemistry, Universidad de Costa Rica, Ciudad Universitaria, Costa Rica |
| Abstract: | New dinuclear TiIV and TiIII complexes with the calix[4]arene ligand C28H20O4H4 (H4L) have been isolated from the reaction of Ti(NMe2)4, H4L, and Na (or KC8) in THF. X-ray analyses revealed a similar core structure for the two complexes Na4(THF)8[TiIV 2(μ-O)2L2] (1) and K4(THF)8[TiIII 2(μ-NMe2)2L2] (2). Two titanium atoms are bridged by two oxygen atoms in 1 and by two dimethylamido groups in 2 and are also supported by two deprotonated calix[4]arene ligands in a cone conformation. This resulted in a similar Ti?Ti separation of about 3.29 Å in 1 and 3.28 Å in 2 and in a distorted octahedral environment for each Ti center in both complexes. In contrast, in a novel complex 3, Na2(THF)6[TiIII 2L2], two TiIII atoms are supported only by two deprotonated ligands. This results in a five-coordinate environment for both titanium(III) centers with the separation between them being 3.133(1) Å. |
| Keywords: | Crystal structures Titanium complexes Calix[4]arene ligands |
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