The salt elimination reaction of the transition carbonyl metallates [L(CO),M](Na/K) (M = Cr, Mo, W, Mn, Re, Fe, Co, Ni; L = CO, q5-C5RS, PR3; n = 1-4; R = alkyl, aryl) with the base-stabilized galliumhalides C1,GaR3 -.(Do) (R = H, alkyl, halide; Do = THF, N(CH3)3, NC7HI3) or Cl,Ga[(CH&N-R;](R), -a yielded almost quantitatively the transition metalsubstituted, gallanes [L(CO) The chemistry of transition metal-substituted gallanes is currently attracting increasing attention, because of their potential as single source precursors to deposit binary intermetallic materials, e.g. P-CoGa and q-MnGa, by low-pressure metal organic chemical vapor deposition [']. But apart from this potential application in microelectronics, this class of compounds is also interesting from a puristic chemical point of view. Firstly, non-bridged and highly polar metal metal bonds are rather popular at the momentr21. In this respect the o(M-E) systems (E = Al, Ga, In; M = transition metal) are the direct main group analogs of transition metal lanthanoide and actinoide complexes, which have a long traditionL3]. Secondly, base-free R2E moieties are isolobal to cationic carbenoid groups such as silylenes, germylenes, and stannylenes. (The C,-symmetric E(R')(NR3) moieties may be viewed as the corresponding neutral congeners.) Thus, they are potential candidates for n-interactions with electron-rich transition metal fragments, which is probably the case for cis-[Cy2PCH2CH2PCy2](R)Pt-ER2 (Cy = c y c l~-C~H~~; E = Ga: R = CH2tBu; E = In: R = CH2SiMe3) [4,17]. To the best of our knowledge, Table 1 summarizes all compounds with (unbridged) M -Ga bonds which have been structurally characterized to date. In this paper we give a comprehensive account on our studies of the synthesis, properties and structural aspects of new M-Ga bonded compounds. A. SynthesisThe monovalent carbonyl metallates [(CO),M](Na/K) (M = Mn, Re, Co; n = 5,4), which were suspended in nonpolar and non-coordinating solvents (n-pentane, toluene) reacted with the base-stabilized alkylgallium chlorides CIGa(R)2(Do) (R = C1, H, Et; Do = NMe,, C7HI3N) quantitatively above -20 "C within minutes to yield the soluble complexes 4a-d, 5a-b, 6a-c (Scheme 1, Table 2). The hydrido compounds 4b, 5b, and 6b are difficult to handle, which is due to their extreme sensitivity to air and temp. (> 0 "C). For this reason, a satisfactory elemental analysis could not be obtained for 5b. The gallium center is coordinatively saturated by adduct formation with one molecule of a Lewis base donor. Without such a base equivalent the substitution reaction (and the alkali halide elimination) does not take place. The same was observed, if polar coordinating solvents, e.g. THF, dimethoxyethane and acetonitrile or HMPT were used. Then the solution v(C0)-IR spectra exhibit the v(C0) absorption bands of the unchanged carbonyl metallates. The intramolecularly adductstabilized organogallium chlorides Cl,Ga[(CH2)3NR;]-(R2 -J (a = 1, 2; R' = Me, Et) selectively gave mono-and disubstituted compounds when treated with stoic...

Abstract:The synthesis and properties of [Ga(N,),], (1) and the related derivatives [(Do),Ga(N,),] (2a-d: Do = THF, NEt,, NMe,, quinuclidine, n = 1; 2e: Do = pyridine; n = 3

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gas-phase precursor reaction, have been reported. ["] In our experiments, relatively high substrate temperatures were chosen (600-650 "C) to accommodate the higher decomposition temperature of the other precursors. These results indicated that, although the films were depleted in Ce, empirical relationships may be established to allow control of deposit composition by the solution composition. Such relationships are very complex, however, and much more experimental work will be needed before definitive predictive relationships can be given.For use as practical 02-selective membranes, CVD deposits such as the one depicted in Figure 3 must be defect free, in addition to possessing desirable oxygen transport properties. The oxygen transport properties may be characterized by conductivity measurements or by direct oxygen permeation measurements at high temperature. The membrane layer must be essentially leak (defect) free before meaningful oxygen permeation measurements can be done. The doped, stabilized ZrOz membranes fabricated thus far have had rather high leakage rates. We believe this is partially due to the relatively large pore size and nonuniform surface of the porous substrates, which may make complete pore blockage difficult to achieve. Unfortunately, there are very limited choices for porous supports available commercially. We are therefore investigating support surface modifications to make the surface more planar and reduce the pore size, as well as investigating reducedpressure deposition more closely.In summary, CeOz-doped Y203.stabilized Zr02 films have been deposited onto porous substrates at atmospheric and reduced pressures by AACVD using a single precursor solution of metal tmhd precursors. Single-phase CeOzdoped stabilized cubic ZrOz was obtained as-deposited over a range of compositions. Reduced-pressure deposition (-10 torr) resulted in a more uniform deposit morphology, and lower C incorporation due to higher relative 0 2 content in the vapor mixture. Preliminary characterization indicates that the deposit and precursor solution compositions differ, but that empirical relationships between solution and film compositions can be employed to control the composition of the deposit. Leak-tight layers for membrane applications have not yet been produced. This is a challenging task requiring good control of the support structure, as well as the CVD process. In general, AACVD is a useful technique for deposition of multicomponent metal oxide films, particularly when precursors with poor volatility or thermal stability are involved.The group-I11 nitrides AlN, GaN, and InN are candidates for applications as light-emitting diodes and semiconductor lasers operating at short wavelengths of the optical spectrum. These materials have several advantages, including direct bandgaps for high efficiency in optoelectronic devices, high radiation hardness, and complete solubility among the binary compounds. Hexagonal CaN is of particular interest because of its potential as a wide-bandgap (3.45 eV) electroluminesc...

The organogallium azides (N3)2 - a (R) a Ga[(CH2)3NMe2]1 - a (1a-c:  R = CH3, tBu; a = 0, 1), (Et)(N3)2Ga (2a), and (Et)(N3)2Ga·L (2b − d:  L = thf, H2NtBu, py, NC7H13) are quantitatively synthesized by salt metathesis from the chloro species (Cl)2 - a (R) a Ga[(CH2)3NMe2]1 - a (a = 0, 1) or EtGaCl2 and sodium azide. The preferential ammonolysis of Ga−N3 bonds for [Et2Ga(N3)]3 (4) and 1 and 2 is demonstrated; e.g. the dimer Et2Ga(μ-NH2)(μ-N3)GaEt2 (3) was obtained. The characterization of these compounds by means of elemental analysis, 1H-, 13C-, 14N-, and 15N-NMR, MS, and infrared ν(N3) data is reported. The dynamics of the intramolecular Ga−N donor−acceptor bonded heterocycle and the azide group is discussed on the basis of variable-temperature NMR data. The barrier of activation of the bimolecular azide exchange process for (N3)2Ga[(CH2)3NMe2] (1c) amounts about 50 kJ·mol-1. The role of ammonia as reactive carrier gas for low-pressure metal organic chemical vapor deposition (MOCVD) of GaN with 1c as precursor is discussed.