Precursors for MOCVD and ALD of Rare Earth Oxides−Complexes of the Early Lanthanides with a Donor-Functionalized Alkoxide Ligand

• Published in: Inorganic chemistry 2007-07, Vol.46 (15), p.5852-5860
• Main Authors: Aspinall, Helen C, Bickley, Jamie F, Gaskell, Jeffrey M, Jones, Anthony C, Labat, Gael, Chalker, Paul R, Williams, Paul A
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic061382y

Complexes of the early lanthanides with the donor-functionalized alkoxide ligand mmp (Hmmp = HOCMe2CH2OMe, 1-methoxy-2-methylpropan-2-ol) are excellent precursors for Metal Organic Chemical Vapor Deposition (MOCVD) and Atomic Layer Deposition (ALD) of lanthanide oxides; however, their coordination chemistry, which is the subject of this paper, is rather complex. Precursors for MOCVD and ALD of lanthanide oxides are prepared by the reaction of [Ln{N(SiMe3)2}3] with 3 equiv of the alcohol Hmmp in toluene in the presence of 1 equiv of tetraglyme and are indefinitely stable in solution. Reaction of [Ln{N(SiMe3)2}3] with 3 equiv of Hmmp in the absence of stabilizing Lewis bases gives complex condensed products with empirical formula [{Ln(mmp)3- n }2O n ]. These condensed products show poor volatility and are unsatisfactory precursors for MOCVD or ALD of oxides. The cluster complex [La3(μ3,κ2-mmp)2(μ2,κ2-mmp)3(mmp)4] has been prepared by careful reaction of [La{N(SiMe3)2}3] with 4 equiv of Hmmp and has been characterized by single-crystal X-ray diffraction. Salt metathesis reactions using M(mmp) (M = Li or Na) are unreliable routes to [Ln(mmp)3]. Crystals of the heterometallic cluster complex [NaLa3(μ3-OH)(μ3,κ2-mmp)2(μ2,κ2-mmp)4(mmp)3] were isolated from the reaction of [La(NO3)3(tetraglyme)] with 3 equiv of Na(mmp), and crystals of [Li(κ2-Hmmp)Pr(μ2,η2-mmp)4)LiCl] were isolated from the reaction of PrCl3 with 3 equiv of Li(mmp); both of these complexes have been characterized by single-crystal X-ray diffraction.