A [{TiCl₂(isodiCp)}₂(μ-O)] Dimer and a Twinned Cyclic [TiCl(isodiCp)(μ-O)]₄Tetramer

Abstract

The mu-oxo dimer mu-oxo-bis[dichloro[(1,2,3,3a,7a-eta)- 4,5,6,7-tetrahydro-4,7-methano-1H-indenyl]titanium], [Ti2Cl4(mu-O)(C10H11)2], and the mu-oxo cyclic tetramer, cyclo-tetra-mu-oxo-tetrakis[chloro[(1,2,3,3a,7a-eta)-4,5,6,7-tetrahydro- 4,7-methano-1H-indenyl]titanium], [Ti4Cl4(mu-O)4(C10H11)4], have been synthesized by electrophilic attack of TiCl4 on the exo-trimethylsilyl derivative of isodiCp (isodiCp is the isodicyclopentadienide anion or 4,5,6,7-tetrahydro-4,7-methano-1H-indene) in the presence of trace amounts of moisture. Both structures are endo isomers, with each Ti atom bonded in a eta 5 manner to the Cp ring of the isodiCp ligand. Both display a slight bending of the isodiCp group about the bond common to the Cp ring and the norbornane fragment, such that the norbornane group is displaced in the direction away from the Ti atom. The dihedral angles which describe this bending are 9.0 (3) and 10.2 (3) degrees for the dimer, and 9.2 (2) degrees for the tetramer. The dimer contains a bent Ti-O-Ti angle of 159.5 (2) degrees. The tetramer forms tetragonal crystals, which are twinned by merohedry on the (110) plane. The tetramer molecule contains a crystallographic 4 axis, with the Ti atoms linked by the O atoms in a mu-oxo manner to form an eight-membered ring.

Structural and Functional Evolution of Metallacrowns

“…These metallamacrocycles typically have either a square or rectangular shape, although the polygon can be slightly distorted in many instances. 8-MC-4 complexes with oxygen atom connectivity have been synthesized with Li I , 560 Al III , [561][562][563] Ti IV (Figure 94), [564][565][566][567][568][569][570][571][572][573][574][575][576][577][578][579][580] V IV , 581,582 V V , 583-587 mixed-valent V IV 2 V V 2 , 588,589 Mn II , 590 Mn III , 591,592 mixed-valent Mn II Mn III 3 , 593,594 Fe III , [595][596][597][598][599][600][601] Co II , 590 Ni II , 602,603 Cu I , [604][605][606][607] Cu II , 590,608-619 Zn II , 602,620-625 Ge IV , 626,627 Nb IV , 628 Nb V , [629][630][631]...…”

“…These metallamacrocycles typically have either a square or rectangular shape, although the polygon can be slightly distorted in many instances. 8-MC-4 complexes with oxygen atom connectivity have been synthesized with Li I , Al III , − Ti IV (Figure ), − V IV , , V V , − mixed-valent V IV 2 V V 2 , , Mn II , Mn III , , mixed-valent Mn II Mn III 3 , , Fe III , − Co II , Ni II , , Cu I , − Cu II , ,− Zn II , ,− Ge IV , , Nb IV ,…”

Synthesis and Characterisation of Various Diester and Triester Adducts of TiCl4

“…The bridging Ti-O-Ti bond angle is 177.3(5)°which is similar to other oxo-bridged titanium chloride dimers with alkoxide ligands that are less sterically hindering. [25,26] In the presence of bulkier ligands, more acute oxo bridge angles have been reported. [27] The formation of the dimer demonstrates how air/moisture sensitive this system is and how any form of oxygen can stabilise the product.…”

“…This effect has been reported with similar titanium chloride complexes, leading to oxo bridged dimers and tetramers. [25] The bond lengths between the bridging oxygen and the titanium centres was 1.741(7) and 1.863(7) Å, showing the bonding to be covalent in nature. [26] The bridging oxygen stabilised the system and similar bridging compounds have been reported before as easier to crystallise when large stabilising ligands are removed.…”