title: Monomeric, Four-Coordinate Group 4 Metal Complexes with Chelating Bis(tert-butylamido)cyclodisilazane Ligands: Syntheses and Molecular Structures of {(MeSiN(t)Bu)(2)(N(t)Bu)(2)}MCl(2) and {(MeSiN(t)Bu)(2)(N(t)Bu)(2)}MMe(2), M = Zr, Hf.
abstract: The interaction of (MeSiN(t)Bu)(2)(N(t)BuLi)(2) with MCl(4) in hot toluene produces {(MeSiN(t)Bu)(2)(N(t)Bu)(2)}MCl(2,) M = Zr (1), Hf (2), in good yields. The light-yellow and colorless solids are isostructural and crystallize in the monoclinic crystal system, space group P2(1)/n, with four molecules in the unit cell. The unit cell dimensions for 1 (293 K) are a = 9.174(6) Å, b = 18.027(13) Å, c = 16.515 Å, beta = 98.81(6) degrees, and those for 2 (213 K) are a = 9.1871(1) Å, b = 17.8553(2) Å, c = 16.4770(3) Å, beta = 99.339(1) degrees. The metal atoms are pseudotetrahedrally coordinated by cyclodisilazane and chloride ligands but have one additional weak bonding interaction with a cyclodisilazane ring-nitrogen atom. Treatment of 1 or 2 with 2 equiv of MeMgCl in ether affords the corresponding dimethyl species {(MeSiN(t)Bu)(2)(N(t)Bu)(2)}MMe(2), M = Zr (3), Hf (4). These isostructural, colorless organometallic compounds are remarkably stable to atmospheric oxygen and moisture. They crystallize in the monoclinic space group C2/c, Z = 4. The cell parameters for 3 (298 K) are a = 18.867(2) Å, b = 9.361(1) Å, c = 18.059(3) Å, beta = 119.49(1) degrees, and those for 4 (212 K) are a = 18.8066(4) Å, b = 9.3208(2) Å, c = 17.8725(3) Å, beta = 119.508(1) degrees. The dimethyl species are structurally very similar to the dichloro complexes 1 and 2, with the notable exception that the metal centers in these organometallic compounds are truly four-coordinate.
authors.affiliation: Department of Chemistry, St. Cloud State University, St. Cloud, Minnesota 56301-4498.
authors.forename: Luke
authors.initials: L
authors.lastname: Grocholl
authors.forename: Volker
authors.initials: V
authors.lastname: Huch
authors.forename: Lothar
authors.initials: L
authors.lastname: Stahl
authors.forename: Richard J.
authors.initials: RJ
authors.lastname: Staples
authors.forename: Phaedra
authors.initials: P
authors.lastname: Steinhart
authors.forename: Alison
authors.initials: A
authors.lastname: Johnson