Crystal indium compounds

The observation of more wetikly a regated oligomeric species for the heavier metals is in accord with observations made for related Cp M compounds (M = Al-Tl). Thus, although all four compounds vaporize as monomeric species [145-148], the aluminum compound crystallizes as a tetramer, with mean Al-Al distances (2.769 A), which are not markedly different from 28 (2.739 A), and which are shorter than the intermettJlic separations in aluminum metal (2.86 A) [131]. By contrast, both the gtdlium and indium compounds crystallize as loosely bound hexamers (Cp M)g, which have structures that can be viewed as octahedra, distorted by compression along a C3 axis [147, 149]. In addition, and in contrast to (Cp Al)4, the r -Cp centroid-M vectors lie not radial to the metal core, but tilted to give overtJl 5j symmetry. One interpretation of these structural distortions is in terms of a second order Jtihn-Teller effect, which maximizes M-M orbital overlap ... 

The Group 13 dichlorides of formula Ar MCb [AT = 8-(dimethylamino)-l-naphthyl M = Al, Ga or In) have been prepared by the salt elimination reaction of one equivalent of Ar Li with MCI3 in toluene solution at -78 °C. The X-ray crystal structures show that the aluminium and gallium compounds are monomeric while the indium compound is dimeric. Reduction of the aluminium monomer with LiAlH4 gives the dimeric dihydride [Ar AlH2]2. There has been a report of the first structurally characterised aluminium compounds with terminal acetylide groups (24, 25). ... 

The synthesis and characterization of the monomeric amidinato-indium(I) and thallium(I) complexes [Bu C(NAr)2]M[But(NAr(NHAr)] (M = In, Tl Ar = 2,6-Pr2CgH3) have been reported. Both compounds were isolated as pale yellow crystals in 72-74% yield. These complexes, in which the metal center is chelated by the amidinate ligand in an N, j -arene-fashion (Scheme 33), can be considered as isomers of four-membered Group 13 metal(I) carbene analogs. Theoretical studies have compared the relative energies of both isomeric forms of a model compound, In[HC(NPh)2]. ... 

Tris(0-ethyl dithiocarbonato)chromium(III) is obtained as a dark blue crystalline powder which decomposes at 100 to 140°. The indium(III) ethylxanthate complex forms small colorless crystals which decompose at 130 to 150°.16,17 The cobalt (III) ethylxanthate complex is isolated as a dark green crystalline powder whose decomposition temperature determined by use of a thermal balance is 135 to 137° (lit. value, 117° 2 118 to 119°8). These compounds decompose slowly in air and more rapidly when heated in solution. The tripositive chromium, indium, and cobalt complexes are insoluble in water but are soluble in many organic solvents (Table T). 

One of the first published cluster compounds of the heavier group 13 elements was the closo-dodecaaluminate K2[Ali2iBui2] 54 (Figure 2.3-10) [79], which possesses an almost undistorted icosahedron of 12 aluminum atoms with short Al-Al distances (268-270 pm). Up until today, it remained the only homonuclear cluster compound of the elements aluminum to indium which, with respect to structure and cluster electron count, is completely analogous to any boronhydride (see Chapters 1.1.2, 1.1.3, 1.1.5.2, and 2.1.5.6) (in this case doso-[Bi2H12]2 ). Compound 54 was formed in small quantities by the reaction of di(isobutyl)aluminum chloride with potassium and was isolated as dark red crystals (Figure 2.3-10). 

The reaction of toluene solutions of indium trichloride and tris(trimethylsilyl)arsine resulted in the formation of a very fine dark-brown powder subsequently annealed up to 400°C to drive to completion the elimination of trimethyl-silyl-chloride. Nanocrystalline InAs was obtained. Similar reactions with InBr3 and Inl3 and P compounds have been discussed. Previously a similar reaction was described by Uchida et al. (1993) (reaction of indium acetylacetonate with tris(trimethylsilyl)arsine in refluxing triglyme). Subsequently the reaction with InCl3 was used by Guzelian et al. (1996) in the preparation of nano-crystal quantum dots. They compared different preparation methods and techniques useful to isolate specific size distributions. 

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