interface engineering, in addition to effective doping strategies involving scalable and highly precise processing technology on large areas, have been deemed necessary to advance the development of p-type oxide materials. [5] Atomic layer deposition (ALD) is a layerby-layer thin film deposition method that allows for atomic-level control over thickness and material/interface properties, resulting in conformal and uniform deposition over large areas, and high aspect ratio substrates. [9,10] Such unique features stem from the fact that ALD relies on cyclic and self-limiting chemical reactions between the substrate surface and alternating exposure to a precursor and coreactant. [11] Recently, mobilities of 0.5, 1, and 6 cm 2 V -1 s -1 and on-current/off-current (I On /I Off ) ratios of 10 4 , 10 6 , and 10 2 have been reported for SnO deposited by temporal ALD, using bis(1-dimethylamino-2-methyl-2-butoxy)tin, Sn(dmamb) 2 , bis(1-dimethylamino-2-methyl-2-propoxy)tin Sn(dmamp) 2 , and N,N′-tert-butyl-1,1-dimethylethylenediamine stannylene(II), [12][13][14] respectively, as the Sn precursor with an H 2 O coreactant. Whilst these results are promising for the development of p-type transistors by ALD, the low deposition rate of temporal ALD, coupled with the low reactivity of current precursor technology may ultimately hinder large area industrial applications. The development of high deposition rate processes (i.e., high growth per cycle (GPC) and/or short cycle time) with atomic-level control, suitable for large-area applications, are therefore of paramount importance. High-throughput ALD can be obtained by improving two major aspects of the process; i) upgrades in deposition hardware (i.e., deposition equipment and methodology), which have the potential to reduce the overall cycle time and or ii) improvement of the underpinning chemistries involved (i.e., the development of novel and chemically optimized precursors) which can increase the GPC, and shorten overall cycle time, thus increasing deposition rate by harnessing higher reactivity with the substrate surface and coreactant.In conventional temporal ALD substrates are exposed to alternate precursor and coreactant doses which are separated in time by extensive purge steps to eliminate precursor mixing and afford self-limited deposition in a cyclic fashion. In contrast to temporal ALD, spatial ALD (sALD) relies on Spatial atomic layer deposition (sALD) of p-type SnO is demonstrated using a novel liquid ALD precursor, tin(II)-bis(tert-amyloxide), Sn(TAA) 2 , and H 2 O as the coreactant in a process which shows an increased deposition rate when compared to conventional temporal ALD. Compared to previously reported temporal ALD chemistries for the deposition of SnO, deposition rates of up to 19.5 times higher are obtained using Sn(TAA) 2 as a precursor in combination with atmospheric pressure sALD. Growths per cycle of 0.55 and 0.09 Å are measured at deposition temperatures of 100 and 210 °C, respectively. Common-gate thin film transistors (TFTs), fabricated using sAL...

A new series of tin(II) complexes (1, 2, 4, and 5) were successfully synthesized by employing hydroxy functionalized pyridine ligands, specifically 2-hydroxypyridine (hpH), 8-hydroxyquinoline (hqH), and 10-hydroxybenzo[h]quinoline (hbqH) as stabilizing ligands. Complexes [Sn(μ-κ2ON-OC5H4N)(N{SiMe3}2)]2 (1) and [Sn4(μ-κ2ON-OC5H4N)6(κ1O-OC5H4N)2] (2) are the first structurally characterized examples of tin(II) oxypyridinato complexes exhibiting {Sn2(OCN)2} heterocyclic cores. As part of our study, 1H DOSY NMR experiments were undertaken using an external calibration curve (ECC) approach, with temperature-independent normalized diffusion coefficients, to determine the nature of oligomerisation of 2 in solution. An experimentally determined diffusion coefficient (298 K) of 6.87 × 10−10 m2 s−1 corresponds to a hydrodynamic radius of Ca. 4.95 Å. This is consistent with the observation of an averaged hydrodynamic radii and equilibria between dimeric [Sn{hp}2]2 and tetrameric [Sn{hp}2]4 species at 298 K. Testing this hypothesis, 1H DOSY NMR experiments were undertaken at regular intervals between 298 K–348 K and show a clear change in the calculated hydrodynamic radii form 4.95 Å (298 K) to 4.35 Å (348 K) consistent with a tetramer ⇄ dimer equilibria which lies towards the dimeric species at higher temperatures. Using these data, thermodynamic parameters for the equilibrium (ΔH° = 70.4 (±9.22) kJ mol−1, ΔS° = 259 (±29.5) J K−1 mol−1 and ΔG°298 = −6.97 (±12.7) kJ mol−1) were calculated. In the course of our studies, the Sn(II) oxo cluster, [Sn6(m3-O)6(OR)4:{Sn(II)(OR)2}2] (3) (R = C5H4N) was serendipitously isolated, and its molecular structure was determined by single-crystal X-ray diffraction analysis. However, attempts to characterise the complex by multinuclear NMR spectroscopy were thwarted by solubility issues, and attempts to synthesise 3 on a larger scale were unsuccessful. In contrast to the oligomeric structures observed for 1 and 2, single-crystal X-ray diffraction studies unambiguously establish the monomeric 4-coordinate solid-state structures of [Sn(κ2ON-OC9H6N)2)] (4) and [Sn(κ2ON-OC13H8N)2)] (5).

Analogous to the ubiquitous alkoxide ligand, metal boroxide and boryloxy complexes are an underexplored class of hard anionic O − ligand. A new series of amine-stabilized Li, Sn(II), and Zn boryloxy complexes, comprising electron-rich tetrahedral boron centers have been synthesized and characterized. All complexes have been characterized by one-dimensional (1D), two-dimensional (2D), and DOSY NMR, which are consistent with the solid-state structures unambiguously determined via single-crystal X-ray diffraction. Electron-rich μ 2 -(Sn and Zn) and μ 3 -(Li) boryloxy binding modes are observed. Compounds 6−9 are the first complexes of this class, with the chelating bis-and trisphenol ligands providing a scaffold that can be easily functionalized and provides access to the boronic acid pro-ligand, hence allowing facile direct synthesis of the resulting compounds. Computational quantum chemical studies suggest a significant enhancement of the π-donor ability of the amine-stabilized boryloxy ligand because of electron donation from the amine functionality into the porbital of the boron atom.

A family of zinc phosphate complexes supported by nitrogen donor-base ligands have been synthesized, and their molecular structures were identified in both the solid (X-ray crystallography) and solution state (DOSY NMR spectroscopy).[Zn{O 2 P(OPh) 2 } 2 ] ∞ (1), formed from the reaction of Zn[N-(SiMe 3 ) 2 ] 2 with HO(O)P(OPh) 2 coordinates to donor-base ligands, i.e., pyridine (Py), 4-methylpyridine (4-MePy), 2,2bipyridine (bipy), tetramethylethylenediamine (TMEDA), pentamethyldiethylenetriamine (PMDETA), and 1,3,5-trimethyl-1,3,5triazacyclohexane (Me 3 -TAC), to produce polymeric 1D structures, [(Py) 2 Zn{O 2 P(OPh 5), and [(Me 3 -TAC)Zn-{O 2 P(OPh) 2 } 2 ] 2 (7), as well as a mono-nuclear zinc bis-diphenylphosphate complex, [(PMDETA)Zn{O 2 P(OPh) 2 } 2 ] (6). 1 H NMR DOSY has been used to calculate averaged molecular weights of the species. Studies are consistent with the disassembly of polymeric 3 into the bimetallic species [(Me-Py) 2 •Zn 2 {O 2 P(OPh) 2 } 4 ], where the Me-Py ligand is in rapid exchange with free Me-Py in solution. Further 1 H DOSY NMR studies of 4 and 5 reveal that dissolution of the complex results in a monomer dimer equilibrium, i.e., [(Bipy)Zn{O 2 P(OPh) 2 } 2 ] 2 ⇆ 2[(Bipy)Zn{O 2 P(OPh) 2 } 2 ] and [(TMEDA)Zn{O 2 P(OPh) 2 } 2 ] 2 ⇆ 2[(TMEDA)-Zn{O 2 P(OPh) 2 } 2 ], respectively, in which the equilibria lie toward formation of the monomer. As part of our studies, variable temperature 1 H DOSY experiments (223 to 313 K) were performed upon 5 in d 8 -tol, which allowed us to approximate the enthalpy [ΔH = −43.2 kJ mol −1 (±3.79)], entropy [ΔS = 109 J mol −1 K −1 (±13.9)], and approximate Gibbs free energy [ΔG = 75.6 kJ mol −1 (±5.62) at 293 K)] of monomer−dimer equilibria. While complex 6 is shown to maintain its monomeric solid-state structure, 1 H DOSY experiments of 7 at 298 K reveal two separate normalized diffusion coefficients consistent with the presence of the bimetallic species [(TAC) 2−x Zn 2 {O 2 P(OPh) 2 } 4 ], (x = 1 or 0) and free TAC ligand.