New types of constrained geometry group 4 metal complexes derived from the aminomethyldicarbollyl ligand system: Synthesis and structural characterization of mono-dicarbollylamino and bis-dicarbollylamino group 4 metal complexes

作者：Lee Jong Dae; Lee Young Joo; Son Ki Chul; Cheong Minserk; Ko Jaejung^*; Kang Sang Ook

来源：Organometallics, 2007, 26(14): 3374-3384.

DOI：10.1021/om0701569

A series of constrained geometry group 4 metal complexes containing the (N,N'-dimethylaminomethyl) dicarbollyl ligand Dcab(N)H [nido-7-NHMe2(CH2)-8-R-7,8-C2B9H10] (3) was prepared. New types of constrained geometry titanium complexes with the formula (Dcab(N))TiCl2, [{(eta(5)-RC2B9H9)(CH2)(eta(1)-NMe2)}TiCl2] (R = H, 4a; Me, 4b), were produced by the reaction of the potassium salt of 3 with titanium tetrachloride. The reaction of 3 with Ti(NMe2)(4) in toluene afforded (Dcab(N))Ti(NMe2)(2), [{(eta(5)-RC2B9H9)(CH2)(eta(1)-NMe2)}Ti(NMe2)(2)] (5) (R = H, a; Me, b), which readily reacted with Me3SiCl to yield the corresponding chloride complexes (Dcab(N))TiCl2 (4). However, the reaction of 3 with Zr(NMe2)(4) in toluene afforded (Dcab(N))Zr(NMe2)(2)(HNMe2) [{(eta(5)-RC2B9H9)(CH2)(eta(1)-NMe2)}Zr(NMe2)(2)(HNMe2)] (6) (R = H, a; Me, b). The structures of the diamido complexes were established by X-ray diffraction studies of 5a and 5b, which authenticated an eta(5);eta(1)-bonding mode derived from the dicarbollylamino ligand functional group. The corresponding bis-chelate complexes, (Dcab(N))(2)Ti (7), were synthesized from the reaction of 4a with an additional dicarbollyl ligand 3a. Bis-chelated complexes (Dcab(N))(2)M (M = Ti, 7; Zr, 8; Hf, 9) were also formed upon the reaction of 3a with MX4 (M = Ti, Zr, Hf) in a 2:1 molar ratio. The NMR spectra revealed that intramolecular M-N coordinations were preserved in solution, resulting in the formation of bis-chelated complexes (Dcab(N))(2)M (7-9). The tetrahedral coordination of the metal center was proven by single-crystal X-ray determination of the complex (Dcab(N))(2)Zr (8). New types of titanium alkoxides, (Dcab(N))Ti((OPr)-Pr-i)(2) (10), were synthesized from the reaction of 3a with Ti((OPr)-Pr-i)(4). Sterically less-demanding phenols such as C6H5OH and 2-MeC6H4OH replaced the coordinated amido ligands on (Dcab(N))Ti(NMe2)(2) (5a) to yield the aryloxy-stabilized CGC complexes (Dcab(N))Ti(OPh)(2) (Ph = C6H5, 11; 2-Me-C6H4, 12). The NMR spectra suggested that an intramolecular Ti-N coordination was intact in solution, resulting in a stable piano-stool structure whereby two aryloxy ligands resided in the leg positions. The aryloxy coordinations were further confirmed by single-crystal X-ray diffraction studies on the complexes (Dcab(N))Ti(OPh)(2) (Ph = C6H5, 11; 2-Me-C6H4, 12).

• 出版日期2007-7-2