Volatility and High Thermal Stability in Mid- to Late-First-Row Transition-Metal Diazadienyl Complexes

Abstract

Treatment of MCl 2 (M = Cr, Mn, Fe, Co, Ni) with 2 equiv of lithium metal and 1,4-di-tertbutyl-1,3-diazadiene ( tBu2 DAD) in tetrahydrofuran at ambient temperature afforded Cr( tBu2 DAD) 2 (38%), Mn( tBu2 DAD) 2 (81%), Fe( tBu2 DAD) 2 (47%), Co( tBu2 DAD) 2 (36%), and Ni( tBu2 DAD) 2 (41%). Crystal structure determinations revealed monomeric complexes that adopt tetrahedral coordination environments and were consistent with tBu2 DAD radical anion ligands. To evaluate the viability of M( tBu2 DAD) 2 (M = Cr, Mn, Fe, Co, Ni) as potential film growth precursors, thermogravimetric analyses, preparative sublimations, and solid-state decomposition studies were performed. Mn( tBu2 DAD) 2 is the most thermally robust among the series, with a solid-state decomposition temperature of 325 °C, a sublimation temperature of 120 °C/0.05 Torr, and a nonvolatile residue of 4.3% in a preparative sublimation. Thermogravimetric traces of all complexes show weight loss regimes from 150 to 225 °C with final percent residues at 500 °C ranging from 1.5 to 3.6%. Thermolysis studies reveal that all complexes except Mn( tBu2 DAD) 2 decompose into their respective crystalline metal powders under an inert atmosphere. Mn( tBu2 DAD) 2 may afford amorphous manganese metal upon thermolysis.

Synthesis and Structures of Mono‐ and Dinuclear Molybdenum Complexes with Reduced α‐Diimine Ligands

“…The five‐membered N(1)C(1)C(2)N(2)Mo [and N(3)C(27)C(28)N(4)Mo] chelating ring is significantly puckered, with the molybdenum atom located out of the C 2 N 2 plane by a vertical distance of 1.17 Å. A number of such ML 2 ‐type complexes of α‐diimine ligands have been reported for both transition‐ and main‐group metals, such as Mg, Ca, Ga, Cr,, Fe, Co, Ni, and Zn . However, the Mo analogue is unknown.…”

“…However, the Mo analogue is unknown. Very recently, the closely related chromium analogues, Cr( t Bu‐DAD) 2 ( t Bu‐DAD = 1,4‐ t Bu 2 ‐1,3‐diazabutadiene) and Cr( H L) 2 , were reported, which contain two radical monoanionic ligands that are antiferromagnetically coupled to a high‐spin d 4 Cr II ion , …”

Low-Temperature Atomic Layer Deposition of Cobalt Oxide as an Effective Catalyst for Photoelectrochemical Water-Splitting Devices

“…Precursor synthesis [Co( tBu2 DAD)2] was synthesized modifying the literature reported procedure (Scheme 1). 49 All manipulations were carried out in an atmosphere of argon purified by Cu catalysts and molecular sieves using standard Schlenk and glove-box techniques. All solvents were dried using an MBraun Solvent Purification System.…”

Classification of processes for the atomic layer deposition of metals based on mechanistic information from density functional theory calculations

“…53 The patent literature includes proposals for the use of Ti diazadienyls as precursors for TiO 2 ALD 54 and Cu diazadienyls for Cu ALD. 55 thermal ALD of Co metal using formic acid (HCOOH) 56 or amines (RNH 2 ) 57 as co-reagents.…”