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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

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The complexes [Cp†Ti(SCHCH2CH2S)]2 (Cp† = Cp (3), MeCp (4)) are readily prepared from reaction of Cp†Ti(SCH2CH2CH2S)Cl (Cp† = Cp (1), MeCp (2)) with MeLi, AlMe3, or t-BuLi. Both compounds are centrosymmetric dimers in the solid state containing strained thiatitanacyclopropane rings. PMe3 cleaves these dimers, establishing equilibria between 3 and 4 and Cp†Ti(SCHCH2CH2S)(PMe3) (Cp† = Cp (5), MeCp (6)), while compound 3 undergoes facile acidolysis with HCl, acetic acid, PhSH, and propanedithiol affording CpTiCl3, CpTi(O2CMe)3 (7), CpTi(SCH2CH2CH2S)(SPh), and H+[CpTi(SCH2CH2CH2S)2]-·THF (8), respectively. The thiametallacycles react with benzophenone to give Cp†Ti(SCH(CPh2O)CH2CH2S) (Cp† = Cp (9); MeCp (10)) while reaction with cyclohexanone gives the dimeric species [Cp†Ti(SCH(C6H10O)CH2CH2S)]2 (Cp† = Cp (11); MeCp (12)). Analogous reactions with 2-methylcyclohexanone, menthone, and nopinone give related addition products with varying degrees of diastereoselectivity. The complex 3 also reacts with a series of imines to give complexes of the form CpTi(SCH(CHRNR)CH2CH2S), where the diastereoselectivity observed is a function of the steric demands of the substrate substituents. Reaction of 3 with nitriles, methyl isocyanate, dicyclohexylcarbodiimide, and phenyl thioisocyanate results in insertion of the substrate and subsequent enolization to give species of the form CpTi(SC=(C(R)NH)CH2CH2S). The analogous reaction with phenyl isocyanate yields the bimetallic complex CpTi(SC(PhNCO)CH2CH2S)TiCp(SCH2CH2CH2S) (27). Crystallographic characterization of a number of these reaction products is reported. Kinetic studies of the formation of 10 and 12 are consistent with initial formation of ketone complex adducts and subsequent intra- and intermolecular C−C bond formation reactions. The nature of the products, reaction mechanisms, and reactivity of strained thiatitanacyclopropane rings are discussed in the light of EHMO calculations.

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