Trialkylphosphine-Stabilized Copper(I) Gallium(III) Phenylchalcogenolate Complexes: Crystal Structures and Generation of Ternary Semiconductors by Thermolysis

Abstract

A series of organometallic trialkylphosphine-stabilized copper gallium phenylchalcogenolate complexes [(R(3)P)(m)Cu(n)Me(2-x)Ga(EPh)(n+x+1)] (R = Me, Et, (i)Pr, (t)Bu; E = S, Se, Te; x = 0, 1) has been prepared and structurally characterized by X-ray diffraction. From their molecular structures three groups of compounds can be distinguished: ionic compounds, ring systems, and cage structures. All these complexes contain one gallium atom bound to one or two methyl groups, whereas the number of copper atoms, and therefore the nuclearity of the complexes, is variable and depends mainly on size and amount of phosphine ligand used in synthesis. The Ga-E bonds are relatively rigid, in contrast to flexible Cu-E bonds. The lengths of the latter are controlled by the coordination number and steric influences. The Ga-E bond lengths depend systematically on the number of methyl groups bound to the gallium atom, with somewhat shorter bonds in monomethyl compounds compared to dimethyl compounds. Quantum chemical computations reproduce this trend and show furthermore that the rotation of one phenyl group around the Ga-E bond is a low energy process with two distinct minima, corresponding to two different conformations found experimentally. Mixtures of different types of chalcogen atoms on molecular scale are possible, and then ligand exchange reactions in solution lead to mixed site occupation. In thermogravimetric studies the complexes were converted into the ternary semiconductors CuGaE(2). The thermolysis reaction is completed at temperatures between 250 and 400 °C, typically with lower temperatures for the heavier chalcogens. Because of significant release of Me(3)Ga during the thermolysis process, and especially in case of copper excess in the precursor complexes, binary copper chalcogenides are obtained as additional thermolysis products. Quaternary semiconductors can be obtained from mixed chalcogen precursors.

Coordination Polymers of Indium/Copper Selenolates and the Preparation of Metal Selenides

“…The SSPs of the type [(PR 3 ) n Cu I (μ‐ER′) 2 M III (ER′) 2 ] (M=Ga, In; R, R′=alkyl, aryl) have been thoroughly investigated for the preparation of chalcopyrite thin film using chemical vapour deposition technique. The organic groups attached to P and E atoms are responsible not only for the structural variation but also the deposition behaviour in the thermolysis process of the precursors . Very often the isolation of such SSPs may be inherently difficult due to instability, non‐formation of bimetallic bridge “Cu(μ‐ER′) 2 In”, or rapid polymerization of the precursors.…”

Synthesis and Application of Monomeric Chalcogenolates of 13 Group Elements

“…reported the synthesis of Ga 2 S 3 and In 2 S 3 nanoparticles by thermally induced destruction of [MeM(SCH 2 CH 2 S)]n (M=Ga, In), that had been shown as suitable SSP despite its polymeric nature. The above mentioned polymers are also suitable starting compounds for the synthesis of [(R 3 P) m Cu n Me 2− x Ga(EPh) n + x +1 ] (R=Me, Et, i Pr, t Bu; E=S, Se, Te; x= 0, 1) that were used as SSPs for the preparation of ternary CuGaE 2 semiconductors . However, all these studies also revealed that synthesis of monomeric chalcogenolates of group 13 elements is rather problematic.…”

“…The above mentioned polymers are also suitables tarting compounds for the synthesis of [(R 3 P) m Cu n Me 2Àx Ga(EPh) n + x + 1 ]( R = Me, Et, iPr, tBu;E = S, Se, Te ; x = 0, 1) that were used as SSPs fort he preparationo f ternary CuGaE 2 semiconductors. [17] However,a ll these studies also revealed that synthesis of monomeric chalcogenolates of group 13 elements is rather problematic.T he Lewis acidic metal centrumisusually involved in intermolecularE!Minteractions,w hich providet heir polymerics tructures making these compounds low volatile and hardly soluble in common organic solvents, therefore unfavorable for SSPs. In 1984, Hofmann [18] et al showed that simple addition of externalL ewis base NMe 3 to the polymericg allium thiolates Ga(SR) 3 (R = CH 3 ,C 2 H 5 , nPr, iPr,P h, CH 2 Ph) provides the monomeric complexes Ga(SR) 3 ·NMe 3 .L ater on, the concept of intramolecular P!Ga interaction stabilized monomeric complex Me 2 Ga{(SC 6 H 4 -2-PPh 2 )-k 2 S,P} ( Figure 2A).…”

Organo‐Gallium/Indium Chalcogenide Complexes of Copper(I): Molecular Structures and Thermal Decomposition to Ternary Semiconductors

“…The molecular precursors are usually stabilized by phosphine ligands coordinating the copper atoms, to prevent uncontrolled oligomerization, and to provide solubility in organic solvents. These ligands are released during the thermal decomposition process, producing the semiconductor material 1b,f,g,i,p,q. 2 Due to its commercial availability, triphenylphosphine has been commonly used for this purpose 1b,c,f,g,i,l–n,o.…”

“…2 Due to its commercial availability, triphenylphosphine has been commonly used for this purpose 1b,c,f,g,i,l–n,o. However, we use trialkylphosphines instead, because they are more volatile, more easily soluble in organic solvents, and provide the possibility to tune their steric demand by varying the size of the alkyl groups, thereby influencing the structure and composition of the complexes, and their thermolysis behavior 1p…”