A family of scandium and yttrium tris((trimethylsilyl)methyl) complexes with neutral N-3 donor ligands

• Published in: Organometallics Vol. 24; no. 13; pp. 3136 - 3148
• Main Authors: Tredget, CS, Lawrence, SC, Ward, BD, Howe, RG, Cowley, AR, Mountford, P
• Format: Journal Article
• Language: English
• Published: WASHINGTON Amer Chemical Soc 20.06.2005
• Subjects: Chemistry; Chemistry, Inorganic & Nuclear; Chemistry, Organic; Physical Sciences; Science & Technology; CATIONIC ALKYL; TRIAZACYCLONONANE; TRIAZACYCLOHEXANE COMPLEXES; RARE-EARTH-METALS; ORGANOMETALLIC COMPLEXES; CHEMISTRY; CRYSTAL-STRUCTURES; COORDINATION; ETHYLENE POLYMERIZATION; ALKYL COMPLEXES
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om050209r

The first group 3 organometallic compounds containing the tris(3,5-dimethylpyrazolyl)methane (HC(Me(2)pz)(3)) and 1,3,5-trimethyltriazacyclohexane (Me-3[6]aneN(3)) ligands are reported, together with the homologous 1,4,7-triazacyclononane-supported compounds and trichloride derivatives for many of the ligands. Reaction of M(CH2SiMe3)(3)(THF)(2) (M = SC, Y) with Me-3[9]aneN(3) (1,4,7-trimethyltriazacyclononane), HC(Me(2)pz)(3), or Me-3[6]aneN(3) gave the corresponding tris((trimethylsilyl)methyl) derivatives M(Me-3[9]aneN(3))(CH2SiMe3)(3) (M = Se (1), Y (2)), M{HC(Me(2)pz)(3)](CH2SiMe3)(3) (M = Sc (3), Y (4)), and M(Me-3[6]aneN(3))(CH2SiMe3)(3) (M = Sc (12), Y (13)). Reaction of 3 with 2,6-dimethylphenol (ArOH) gave the tris(aryloxide) derivative Sc{HC(Me(2)pz)3}(OAr)(3) (9), and reaction of HC(Me(2)pz)(3) with MCl3 gave M{HC(Me(2)pz)(3)]Cl-3 (M = Sc (5), Y(6)). Attempts to prepare tris((trimethylsilyl)methyl) complexes with the more sterically demanding tris(3-R-pyrazolyl)methanes (R = Pr-i, Ph, Bu-t) or the related tris(pyrazolyl)methylsilane ligand were unsuccessful. However, the trichlorides M{HC((i)Prpz)(3)}Cl-3 (M = Sc (7), Y (8)) and M{MeSi(Me(2)pz)(3)}Cl-3 (M = Sc (10), Y (11)) could be made. In related studies the reaction Of ScCl3(THF)(3) with Me-3[6]aneN(3) afforded Sc(Me-3[6]aneN(3))Cl-3 (14), but the yttrium congener could not be prepared. The compounds 1, 3, 4, 9, 11, and 14 have been crystallographically characterized. Competitive ligand exchange reactions for the tris(alkyl) compounds M(L)(CH2SiMe3)(3) established the binding preference L = Me-3[9] aneN(3) > Me-3[6] aneN(3) > HC(Me(2)pz)(3) for M = Sc and L = Me-3[9] aneN(3) > HC(Me(2)pz)(3) > Me-3[6]aneN(3) for M = Y. Reaction of ScR3(THF)(2) (R = CH2SiMe3, Ph) with 1-(3,5-di-tert-butyl-2-hydroxybenzyl)-4,7-dimethyltriazacyclononane (HL1) or 1-(3,5-di-tertbutyl-2-hydroxybenzyl)-4,7-diisopropyltriazacyclononane (HL2) gave organoscandium derivatives of mono(phenoxy)-substituted triazacyclononane ligands, namely Sc(L-1)R-2 (R = CH2SiMe3 (15), Ph (17)) and Sc(L-2)(CH2SiMe3)(2) (16). Reaction of 15 with 2 equiv of TolOH (Tol = p-tolyl) afforded Sc(L-1)(OTol)(2) (18), which was crystallographically characterized.