Synthesis, structure, and reactivity of Lewis acidic cyclopentadienyltitanium dithiolate complexes

Abstract

The reaction of CpTiCl3 with 1,3-propanedithiol yields the mononuclear Ti(IV) species CpTi(SCH2CH2CH2S)Cl (1) . This diamagnetic chelate complex crystallizes in the space group Pi with a = 8.729 (4) A, b = 10.114 (2) A, c = 6.620 (4) A, a = 90.70 (4)°, ß = 109.35 (4)e, y = 97.02 (4)ß, V = 546 (1) A1 23 45678, and Z = 2. Subsequent reaction of 1 with 1 equiv of sodium benzenethiolate yields the species CpTifSC^CI^CF^SXSCeHs) (2). This compounds crystallizes in the space group P2i with a -7.506 (2) A, b = 19.761 (5) A, c = 10.487 (3) A, ß = 102.02(3) °, V = 1521.5 (7) A3, and Z = 4. The Lewis acidity of these Ti(IV) species is demonstrated by their reactivity.For example, reaction of 1 with 2 equiv of sodium benzenethiolate generates the anionic Ti species [CpTi(SCH2CH2CH2S)(SC6H5)2]" (3). In a similar vein, reaction of 1 with Me2PCH2CH2PMe2 yields several products which were identified spectroscopically. These include two isomers formulated as CpTi(SCH2CH2-CH2S)Cl(Me2PCH2CH2PMe2) in which the bidentate phosphine is either dangling or chelated. In addition the compound (CpTi(SCH2CH2CH2S)Cl)2^-Me2PCH2CH2PMe2) (4) is isolated in low yield from this reaction. This species 4 crystallizes in the space group P2\jn with a = 9.058 (5) A, b = 12.941 (8) A, c = 13.340(6) A, ß = 107.11 (4) °, V = 1494 (3) A3, and Z = 4. Alternatively, a donor atom can be incorporated in the dithiolate backbone; thus, reaction of CpTiCl3 with S(CH2CH2SSiMe3)2 affords the compound CpTi(SCH2CH2SCH2CH2S)Cl ( 5).Compound 5 crystallizes in the space group P2\/n with a = 9.146 ( 7) k,b-10.894 (7) A, c = 13.082 (4) A, ß = 106.12 (4)°, V = 1252 (1) A3, and Z = 4. The reaction of 1 with 1 equiv of NaSCH2CH2CH2SNa affords the complex [CpTi(SCH2CH2CH2S)2]Na (6). This compound crystallizes in two forms. 6(i), which is formulated as 6-THF-benzene, crystallizes in the orthorhombic space group P2\2\2\ with a -14.760 (2) A, b = 17.574 (7) A, c -9.546 (2) A, Z = 4, and V = 2476 (2) A3. 6(ii), formulated as 6-2THF, crystallizes in the orthorhombic space group Pna2\ with a = 32.908 (11) A, b = 10.009 (4) A, c = 14.877 (3) A, Z = 4, and V= 4900 (7) A3. Compound 6 adopts two polymeric forms in the solid state. The geometry at Ti is essentially constant with variations occurring in the coordination sphere of the bridging sodium atoms. The reaction of 1 with base and 1 equiv of H20 affords the oxo-bridged bimetallic species [CpTi(SCH2CH2CH2S)]20 (7). This species also crystallizes in two forms crystallizing in either the space group C2 with a = 32.373

Synthesis and structure of titanium diolate complexes derived from CpTiCl3

“…The T-donor ability of the oxygen atoms competes with the cyclopentadienyl ring for metal d-orbitals and thus facilitates the loss of CpH and the formation of 4. Although no direct evidence has been obtained for the proposed intermediates, the known species 7 and the established ability of Ti three-legged piano stool complexes to bind additional donor ligands are consistent with these propositions (2).…”

“…In the case of 3 this formulation was also confirmed crystallographically (vide infra). In a recent report we demonstrated that substitution reactions involving CpTiC13, thiol, and imidazole proceed through a radical mechanism involving a Ti(II1)-imidazole complex intermediate (4). The formation of 1-3 from the diol-imidazole reactions may also proceed through this intermediate.…”

“…More recently, we focused attention on chalcogenide derivatives of monocyclopentadienyl-titanium(1V). We previously described the Lewis acidity of CpTi-thiolate derivatives such as CpTi(SCH,CH,CH,S)Cl and CpTi(SCH,CH,),S)Cl (2).…”

“…under N, and degassed by the freeze-thaw method at least three (m, 4H), 4 3 These compounds were prepared in similar manners, thus only one preparation is described for each method. (i) A mixture of CpTiC1, (660 mg, 3.0 mrnol) and Me3SiOCH2CH2CH2 OSiMe, (333 mg, 1.50 mmol) in 15 mL THF was stirred for 36 h. The solvent was removed in vacuo, and the residue was washed with 2 x 5 mL pentane and dried.…”

Titanthiolat-Aluminiumcarbid-Komplexe durch Aktivierung mehrerer C-H-Bindungen

“…B. CdSe/CdS und CdSe/ ZnS. [4,5] Im Vergleich zu den Kernen wurde eine erhebliche Steigerung der Emissions-Quantenausbeute und eine gröûere Stabilität gegen Oxidation beobachtet. Diese verbesserten Nanokristalle sind als neuartige Fluoreszenzmarker in biologischen Anwendungen mit deutlichen Vorteilen gegenüber traditionellen Fluoreszenzfarbstoffen eingesetzt worden.…”