99398-79-5Relevant articles and documents
Chemical and electrochemical reduction of titanium(IV) aryloxides
Durfee, Loren D.,Latesky, Stanley L.,Rothwell, Ian P.,Huffman, John C.,Folting, Kirsten
, p. 4569 - 4573 (2008/10/08)
A number of mononuclear, homoleptic aryloxides of Ti(IV) and Zr(IV) have been synthesized and their chemical and electrochemical reduction behavior investigated. In particular the complex Ti(OAr-i-Pr2)4 (OAr-i-Pr2 = 2,6-diisopropylphenoxide) undergoes a reversible, one-electron reduction in tetrahydrofuran to the anion Ti(OAr-i-Pr2)4-, as demonstrated by both its cyclic voltammogram and electrochemical generation of a solution of the d1 complex. Furthermore, sodium amalgam reduction allows the high-yield synthesis of the salt complex [(thf)2Na·Ti(OAr-i-Pr2)4]. This salt reacts with pyridine to give the purple, neutral complex Ti(OAr-i-Pr2)3(py)2. X-ray diffraction studies of Ti(OAr-i-Pr2)4 and its one-electron-reduced anion have allowed a comparison of the bonding properties of titanium(III) and titanium(IV) in similar coordination environments. Crystal data for Ti(OAr-i-Pr2)4 at -160°C: a = 20.811 (8) A?, b = 11.068 (3) A?, c = 19.797 (8) A?, β = 75.48 (2)°, Z = 4, and dcalcd = 1.139 g cm-3 in space group I2/a. Crystal data for [(thf)2NaTi(OAr-i-Pr2)4] at -159°C: a = 20.888 (13) A?, b = 12.958 (9) A?, c = 19.775 (14) A?, Z = 4, and dcalcd = 1.147 g cm-3 in space group P212121. The solid-state structure of Ti(OAr-i-Pr2)4 shows the titanium atom surrounded by four aryloxides in an almost perfect tetrahedral geometry. The Ti-O distances are short (1.78 A?, average), consistent with significant oxygen-p to metal-d π-bonding. In the salt complex [(thf)2Na·Ti(OAr′-i-Pr2)4] the titanium remains coordinated to four aryloxides, but now two of them are bridging to the sodium atom, which also contains two coordinated thf molecules.
