Mono- and Dilithiation of [(η7‑C7H7)Ti(η5‑C5Me5)] (Pentamethyltroticene) for the Synthesis of Troticenyl Monophosphanes and [2]Troticenophanes with C–P and C–Si Bridges

Pentamethyltroticene, [(η7-C7H7)­Ti­(η5-C5Me5)] (1), can be selectively metalated at the C7H7 ring or at both the C5Me5 and C7H7 rings using pmdta/nBuLi or pmdta/tBuLi mixtures (pmdta = N,N′,N′,N″,N″-pentamethyldiethylenetriamine) in 1/1 and 1/4 ratios, respectively. The mono- and dilithiated species [(η7-C7H6Li)­Ti­(η5-C5Me5)]·pmdta (2) and [(η7-C7H6Li)­Ti­(η5-C5Me4CH2Li)]·pmdta (3) were isolated in high yield and characterized by NMR spectroscopy and elemental analysis. Compound 2 was used to synthesize the pentamethyltroticenyl monophosphane [(η7-C7H6PPh2)­Ti­(η5-C5Me5)] (4) by reaction with Ph2PCl, while 3 was treated with RPCl2 (R = Ph, Mes) or Me2SiCl2 to give the carbaphospha- and carbasila[2]­troticenophanes [(η7-C7H6)­Ti­(η5-C5Me4CH2)]­PR (5, R = Ph; 6, R = Mes) and [(η7-C7H6)­Ti­(η5-C5Me4CH2)]­SiMe2 (8). The chiral phosphanes 5 and 6 are the first examples of non-iron metallocenophanes with a phosphorus atom in the bridge. The coordination ability of 4 and 6 toward transition metals was demonstrated by reaction with Mo­(CO)6 and [(tht)­AuCl] (tht = tetrahydrothiophene) or Me2SAuCl and formation of the bimetallic complexes [{η7-C7H6PPh2·Mo­(CO)5}­Ti­(η5-C5Me5)] (9), [(η7-C7H6PPh2·AuCl)­Ti­(η5-C5Me5)] (10), and [(η7-C7H6)­Ti­(η5-C5Me4CH2)]­PMes·AuCl (11). These compounds were structurally characterized by multinuclear 1H, 13C, 31P, and 29Si NMR spectroscopy, UV/vis spectroscopy, electron ionization mass spectrometry (EI–MS), elemental analysis, and single-crystal X-ray diffraction analysis. The molecular structures of 5, 6 and 8 reveal strained sandwich compounds with tilt angles (α) of 18.5(1)° (5), 19.7(7)° (6), and 13.4(2)° (8). Treatment of 2 with ZnCl2 afforded the pentamethyltroticenyl zinc chloride [(η7-C7H6ZnCl)­Ti­(η5-C5Me5)] (12), which was employed in palladium-catalyzed Negishi C–C cross-coupling reactions with phenyl iodide and iodotroticene to afford phenylpentamethyltroticene [(η7-C7H6Ph)­Ti­(η5-C5Me5)] (13) and the [7–5]­bitroticene [(η7-C7H6)­Ti­{μ-η5:η7-(C5H4-C7H6)}­Ti­(η5-C5Me5)] (14), which bears a bridging sesquifulvalene ligand. The molecular structures of 13 and 14 in the solid state were also determined by single-crystal X-ray diffraction analysis.