A Family of Group 4 Metal Alkoxo Complexes with an M₃(μ₃‐O) Core Relevant to Ziegler–Natta Catalyst Intermediates

Abstract

Reactions of [Mg(thffo)(2)] (1) or [Ca(thffo)(2)] (2) with ZrCl(4) or HfCl(4) in a CH(2)Cl(2)/THF/CH(3)CN mixture give thermally stable neutral heterobimetallic tetranuclear complexes [M(3)M'(mu(x)-O)(mu,eta(2)-thffo)(6)(Cl)(6)] (thffo=tetrahydrofurfuroxide; M/M'/x: 3, Zr/Mg/3; 4, Hf/Mg/3; 5, Zr/Ca/4; 6, Hf/Ca/4) as colorless crystals in 75-82 % yield. X-ray diffraction studies show complexes 3-5 to contain oxo-bridged M(3) triangles that are capped by an alkaline earth metal-containing moiety to form species of C(3) symmetry. Reactions of ZrCl(4) and HfCl(4) with pure tetrahydrofurfuryl alcohol in EtOH and MeOH provide ionic complexes [M(3)(mu(3)-O)(mu,eta(2)-thffo)(3)(L)(3)(Cl)(6)]Cl (M/L: 8, Zr/EtOH; 9, Hf/EtOH; 10, Zr/MeOH) in 66-79 % yield. Complexes 8-10 consist of M(3) triangles that are analogous to those in 3-6 and possess similar overall symmetry, as shown by X-ray crystallography. Changes in the reaction conditions afforded the asymmetric neutral dimer [Zr(2)(mu-thffo)(2)(thffoH)(Cl)(6)] (7) and the homometallic [Zr(3)(mu(3)-O)(mu,eta(2)-thp)(3)(thf)(2)(Cl)(7)] (11).

Unexpected Reactions between Ziegler–Natta Catalyst Components and Structural Characterization of Resulting Intermediates

“…34 The results of our previous research and identification of various compounds fit well with the above results; for example, we found that the reaction of magnesium alkoxide [Mg 4 (thffo) 8 ] (where thffo = 2-tetrahydrofurfuroxide) with [Ti(dipp) 4 ] (dippOH = 2,6diisopropylphenol) led to [Mg 4 (thffo) 6 {OTi(dipp) 3 } 2 ] (6). 52,53 Furthermore, the tetramer [Mg 4 (thffo) 8 ] can be trapped by Ph 3 SiOH to form [Mg 4 (thffo) 6 (OSiPh 3 ) 2 ] (7) (see Scheme 3). 54 This shows that magnesium alkoxides can easily be trapped by  SiOH silica surface groups during heterogeneous catalyst preparation.…”

cis-Dichloridobis[2-(hydroxymethyl)tetrahydrofuran-κ2O,O′]manganese(II)

“…For general background, see: Bradley (1989); Hubert-Pfalzgraf (1998); Jerzykiewicz et al (1997Jerzykiewicz et al ( , 2007a; Janas et al (1997Janas et al ( , 1999; Sobota et al (1998aSobota et al ( ,b, 2000a; Utko et al (2003)ÁFor related compounds, see: Wu et al (2004); Lumme & Lindell (1988); Choudhury et al (2006); Yang et al (2003).…”

“…The investigation presented in this work is a part of our research project concerning complexes with O,O′-bifunctional ligands (Jerzykiewicz et al, 1997;Janas et al, 1997;Sobota et al, 1998a;Sobota et al, 1998b;Janas et al, 1999;Sobota et al, 2000a;Sobota et al, 2000b;Utko et al, 2003, Jerzykiewicz et al, 2007aJerzykiewicz et al 2007b). The use of chelating alkoxides can provide new compounds which are potential candidates for both sol-gel and metal-organic chemical vapour (MOCV) conversion of the precursor into the ceramic materials (Hubert-Pfalzgraf, 1998;Bradley, 1989).…”

3 Alkali and alkaline-earth metals

“…135 triangles and the relevance of this structure to Ziegler-Natta catalyst intermediates was discussed. 138 Stoichiometries of 1.5 and 2.8 have been found in stable and welldefined ethanol adducts of MgCl 2 , used as catalyst supports in Ziegler-Natta polymerization, using multidimensional solid state NMR spectroscopy. 139 Reactions of MgCp 2 with thiols afforded the cubane complexes [MgCp(m 3 -SR)] 4 (R ~Pr i , Bu t or Cy).…”