A Novel Manganese(II) MOCVD Precursor: Synthesis, Characterization, and Mass Transport Properties of Mn(hfa)₂•tmeda

Abstract

The complex, Mn(hfa) 2 tmeda [(H-hfa ¼ 1, 1,1,5,5,5-hexafluoro-2,4-pentandione, tmeda ¼ N,N,N 0 ,N 0 -tetramethylethylendiamine)], is synthesized in a single-step reaction and characterized by elemental analysis, thermal analysis, and infrared (IR) spectroscopy. The solid-state crystal structure of Mn(hfa) 2 tmeda provides evidence of a mononuclear structure. The thermal analyses show that the complex is thermally stable and can be evaporated to leave less than 2% residue. The complex properties are compared with the first generation, commercially available Mn II and Mn III precursors, Mn(acac) 2 (Hacac ¼ acetylacetone) and Mn(tmhd) 3 (Htmhd ¼ 2,2,6,6-tetramethyl-3,5-heptanedione), respectively. Mn(hfa) 2 tmeda represents the first example of manganese(II) precursor that can be used in the liquid phase without decomposition, thus providing constant evaporation rates, even for long deposition times. It is successfully applied to the reduced-pressure, metal-organic (MO)CVD of the Mn 3 O 4 phase.[**] The authors thank the MIUR for the financial support within the PRIN 2009 N. 20097 Â 44S7_002 (Hybrid materials based on lanthanide complexes for sensing applications) and the FIRB ITALNANONET RBPR05JH2P project. 22

Molecular Engineering of MnII Diamine Diketonate Precursors for the Vapor Deposition of Manganese Oxide Nanostructures

“…= 86 and 99 8Cfor L = hfa and tfa, respectively [22] ) and could be readily sublimed under vacuum ( % 10 À3 mbar). The meltingp oint of Mn(hfa) 2 ·TMEDA at atmospheric pressure was highert han that previously obtained by somei nvestigators, [11,17] but in line with that reportedi napatent quoting the use of this compound as agasoline additive. [22] The molecular structures of the two complexes are displayed in Figure 1, whereas crystallographic and structuralr efinement data, as well as geometrical parameters of DFT-calculated structures, are presented in Ta bles S1 and S2 in the Supporting Information.…”

“…The synthesis of the target adduct was performed following a different procedure from that previously reported . Hhfa (3.4 mL, 23.30 mmol; d= 1.47 g mL −1 ) was slowly added to a stirred aqueous solution of MnCl 2 ⋅ 4 H 2 O [2.37 g, 11.73 mmol, in deionized H 2 O (50 mL)].…”

“…To date, the most used CVD and ALD Mn precursors are mainly based on β‐diketonate derivatives, some of which suffer from poor shelf‐life and/or unfavorable thermal properties, especially if they contain Mn II . In fact, Mn II complexes with nonfluorinated β‐diketonate ligands are reported to readily decompose into Mn III derivatives, yielding poor control of the phase composition of the product. As a consequence, the obtainment of single‐phase Mn 3 O 4 nanomaterials with controlled crystallinity and morphology requires the tailoring of β‐diketonate compound properties at the molecular level.…”

Metal–Organic Derivatives with Fluorinated Ligands as Precursors for Inorganic Nanomaterials

“…357,358 The dimeric structure of [Ag(μ-η 2 ,η 2 -hfac)-(η 3 -diglyme)] 2 contains two silver atoms bridged by four oxygens from the two hfac ligands and a η 3 -chelating diglyme molecule on each silver atom to achieve 7-coordination number for the metal. 127 On the other hand, the tetraglyme and silylated alkyne ligands in the mononuclear complexes [Ag(hfac)(η 3 -tetraglyme)] 127 106 Mn, 370 Co, 371 Cu,105 Zn, 111,372 Cd 373 ), [M(ttac) 2 (TMEDA)] (M = Zn, 142 Ni,143 Cd 144 ), [Cd(ttac) 2 (phen)], 374 [Zn(hfac) 2 (DEA)], 111 and [Ni-(hfac) 2 (pda)] 110 have been isolated and employed as excellent CVD precursors. In these cases, the enhanced Lewis acidity of the metal center due to the presence of fluorinated groups enables it to bind to the ancillary diamine ligand, yielding stable six-coordinated M(II) complexes with MO 4 N 2 environment around the metals.…”

A practical MOCVD approach to the growth of Pr1-xCaxMnO3films on single crystal substrates

“…This approach has the advantage to control only one vaporization temperature and one carrier gas with respect to the need to control three vaporization temperatures and three carrier gas values in case of use of single source precursors. The thermogravimetric analyses of the three single precursors and of the mixture indicate that either the individual precursors or the mixture are thermally stable and vaporize intact in a single step with low residues (about 2–3%) left at 350 °C. The optimized Pr/Ca/Mn ratio of 1.8:0.6:1 in the source mixture produces Pr 0.7 Ca 0.3 MnO 3 films.…”