Reactions of methyl-substituted titanocene–bis(trimethylsilyl)acetylene complexes with acetone azine: crystal structures of (η 5:η 1-C 5HMe 3CH 2CMe 2NH) 2Ti and (C 5Me 5) 2Ti(NCMe 2)

• Published in: Journal of organometallic chemistry 2000-03, Vol.597 (1), p.146-156
• Main Authors: Rep, Marco, Kaagman, Jan-Willem F., Elsevier, Cornelis J., Sedmera, Petr, Hiller, Jörg, Thewalt, Ulf, Horáček, Michal, Mach, Karel
• Format: Article
• Language: English
• Subjects: Acetone azine; Crystal structure; Effect of methyl substituents; Titanium; Titanocene–amide complexes; Titanocene–bis(trimethylsilyl)acetylene complexes
• ISSN: 0022-328X; 1872-8561
• DOI: 10.1016/S0022-328X(99)00671-3

The titanocene–bis(trimethylsilyl)acetylene (BTMSA) complexes Cp′ 2Ti[η 2-C 2(SiMe 3) 2] (Cp′C 5H 5− n Me n ; n=0–5) react with acetone azine Me 2CNNCMe 2 (AA) in two different ways depending on the number of Me substituents at the Cp′ ligands ( n). For n=0–2, BTMSA is replaced by AA, which then undergoes an oxidative addition accompanied by a proton transfer, affording titana-2-isopropyl-4-methyl-2,3-diazacyclopent-3-ene complexes A0– A2. For n=3–5, replacement of the acetylene is followed by the splitting of AA to give either (C 5Me 5) 2Ti(III)(NCMe 2) ( C5) or the Ti(IV) (Cp′A) 2Ti complexes B3 and B4 for n=3 and 4, respectively. The intramolecularly bridging Cp′A ligand 1-(η 5-2,3,5-trimethylcyclopentadienide)-2-(η 1-amide)-2,2′-dimethylethane arises from a formal insertion of the CN bond of isopropylidene amide into a CH bond of one methyl group of the cyclopentadienyl ligands before or after splitting of AA. Crystal structures of C5 and (η 5:η 1-C 5HMe 3CH 2CMe 2NH) 2Ti(IV) ( B4) were determined.