FORMATION OF ETA-1-IMINOACYL COMPOUNDS BY INSERTION OF ISONITRILES IN PENTAMETHYLCYCLOPENTADIENYL TETRAMETHYLFULVENE COMPOUNDS OF TITANIUM AND ZIRCONIUM - INTRAMOLECULAR C-H ACTIVATION OF A PENTAMETHYLCYCLOPENTADIENYL GROUP TO GIVE A TRIDENTATE LIGAND WITH 2 BRIDGED CYCLOPENTADIENYL RINGS AND A TITANIUM VINYL BOND IN THE BRIDGE - MOLECULAR-STRUCTURE OF [ETA-5-ETA-1-ETA-5-C5ME4CH2C(NHXYL)=CN(XYL)CH2C5ME4]TICL AND CP-STAR-[ETA-5-ETA-1-C5ME4CH2C(=NXYL)C(=NXYL)]ZRCL (XYL = 2,6-ME2C6H3)

Cp*FvMCl [Cp* = eta-5-C5Me5, Fv = eta-6-C5Me4CH2; M = Ti (1), Zr (2)] react with CN(2,6-Me2C6H3) (CNXyl) to give eta-1-iminoacyl complexes Cp*[eta-5:eta-1-C5Me4CH2C activated (= NXyl)]MCl [M = Ti (3), Zr (4)] through insertion of the isonitrile into the M-CH2(Fv) bond. Both iminoacyl complexes, 3 and 4, react with free isonitrile to give a second insertion and coupling of two CNXyl molecules with formation of Cp*[eta-5:eta-1-C5Me4CH2C(= NXyl)C activated (= NXyl)]MCl [M = Ti (5), Zr (6)]. The molecular structure of 6 shows a typical bent metallocene geometry around zirconium with two coupled isonitrile fragments attached to a cyclopentadienyl ligand and one of them eta-1-bonded through the carbon atom to the metal. Compound 6 crystallizes in the monoclinic space group P2(1)/n with a = 12.431 (2) angstrom, b = 16.820 (5) angstrom, c = 16.434 (3) angstrom, beta = 102.06 (2)-degrees, V = 3360 (1) angstrom 3, and = 4. The Zr-Cl (2.430 (1) angstrom) and the Zr-C(iminoacyl) [2.336 (2) angstrom] bonds are located in the equatorial plane between the cyclopentadienyl ligands [Cl-Zr-C 97.68 (6)-degrees]. Compound 5 rearranges thermally through C-H activation of a methyl substituent on a pentamethylcyclopentadienyl ligand and forms a bis(peralkylcyclopentadienyl)titanium vinyl chloride complex [eta-5:eta-1:eta-5-C5Me4CH2C(NHXyl) = C activated N(Xyl)CH2C5Me4]TiCl (7), in which the cyclopentadienyl ligands are bridged by a C3NC chain. The bridge itself is bonded to titanium through a regular Ti-C bond, connecting the metal with a C = C fragment of the coupled isonitrile molecules. Crystals of 7 are triclinic, space group P1BAR, with a = 8.946 (1) angstrom, b = 13.499 (3) angstrom, c = 16.360 (3) angstrom, alpha = 102.91 (1)-degrees, beta = 102.81 (1)-degrees, gamma = 108.28 (1)-degrees, V = 1735.3 (6) angstrom 3, and Z = 2. The peralkylcyclopentadienyl ligands form a normal bent metallocene, bridged at the front of the wedge by a five-membered chain. The Ti-Cl [2.374 (1) angstrom] and the Ti-C [2.158 (4) angstrom] bonds are located in the equatorial plane of the titanocene unit [Cl-Ti-C 97.7 (1)-degrees]. Bridging of the cyclopentadienyl ligands is also found for the zirconium complex 6, but the main product results from a 1,3-hydrogen shift in the side chain to give a cyclopentadienyl-amide bidentate ligand and formation of Cp*[eta-5:eta-1-C5Me4CH = C(CH = N activated Xyl)NXyl]ZrCl (8).