Sandeep Dhingra

Open Framework Structures Based on Sex2– Fragments: Synthesis of (Ph4P)[M(Se6)2] (M = Ga, In, TI) in Molten (Ph4P)2Sex

Polychalcogenide compounds with open polymeric frameworks are rare, and they represent a class of compounds in which microporosity might be achieved. Microporous frameworks that are not oxide-based are now attracting interest because of the combination of catalytic and electronic properties they may simultaneously possess. Three new compounds that may be forerunners to such materials have been discovered and are reported here. The reaction of gallium (Ga), indium (In), and thallium (TI) metal with (Ph4P)2Se5 (Ph, phenyl) and an excess of elemental selenium (Se) in a sealed, evacuated Pyrex tube at 200�C yielded small red crystals of (Ph4P)[Ga(Se6)2] (I), (Ph4P)[In(Se6)2] (II), and (Ph4P)[TI(Se6)2] (III), respectively. The [M(Se6)2]– (M = Ga, In, TI) ions form a two-dimensional, open framework filled with Ph4P+ ions. The [M(Se6)2]nn– structure consists of tetrahedral M3+ centers and bridging Se62– ligands, leading to an extended structure in two dimensions. These layers stack perfectly one on top of the other giving rise to one-dimensional channels running down the c axis that are filled with Ph4P+ cations. These cations are situated in the layers, as opposed to between the layers, and the whole structure can be viewed as a template. Compound II shows remarkable thermal stability and melts congruently at 242�C. Upon cooling to room temperature it gives a glassy phase that recrystallizes upon subsequent heating to 160�C.

Hydrothermal synthesis and crystal structure of H3NCH2CH2NH3[In2(HPO4)4]. A novel octahedral–tetrahedral framework indium phosphate with occluded organic cations

The synthesis and structural characterization by single crystal X-ray diffraction of the first organically templated indium phosphate is reported.

Synthesis and structure of the first indium–copper cluster, [Cu6In3(SEt)16]– and its possible relevance to CuInS2

The cluster (Ph4P)[Cu6In3(SEt)16] has been prepared by the reaction of [Cu(CH3CN)4]PF6 with (Ph4P)[In(SEt)4] and its crystal structure shows an adamantoid framework.

Synthesis and properties of the homo- and heteropolychalcogenide [A(Q5)2]2− family (ATe, QS, Se; ASe, QSe). Crystal structures of (Ph4P)2[Te(S5)2] and β-(Ph4P)2[Se(Se5)2]

Abstract The reaction of Na2Te4 with K2S5 in dimethylformamide in the presence of Ph4PCl gave (Ph4P)2[Te(S5)2] (1). Under the same conditions, the reaction of elemental tellurium with Na2Se5 afforded (Ph4P)2[Te(Se5)2] (II), while β-(Ph4P)2[Se(Se5)2] (III) was made by reacting Na2Se5 with I2. The X-ray powder diffraction studies showed that I, II and III are isostructural. The structures of I and III were determined by X-ray single crystal analysis. The [A(Q5)2]2− anions in the two compounds contain either a square-planar Te2+ in I or Se2+ centre in III, which is situated on an inversion centre and chelated by two S52− or Se52− ligands. The bond distances between the central A2+ and its surrounding four Q atoms are TeS(1) = 2.699(2) A and TeS(5) = 2.752(2) A, or SeSe(1) = 2.653(2) A and SeSe(5) = 2.693(2) A. SS bond distances [av. SS = 2.075(12) A] or SeSe bond distances [av. SeSe = 2.314(13) A] are normal and in good agreement with those found in other polysulphide or polyselenide compounds. The conformation of each AQ5 ring in I and III is very close to a “chair”. The solution UV—vis spectra of DMF solutions for all three compounds are reported.

Synthesis, structure and 77Se/119Sn NMR spectroscopy of the new polyselenide, tris(tetraselenido)stannate(IV), [Sn(Se4)3]2−

Abstract The reaction of sodium pentaselenide with SnCl4 or SnCl2·2H2O in dimethylformamide (DMF), in a 3:1 ratio, forms the new soluble anion [Sn(Se4)3]2− in high (>79%) yields. The compound (Ph4P)2[Sn(Se4)3] (I) crystallizes in the monoclinic space group P21/c with unit cell dimensions, a = 13.320(2), b = 11.678(3), c = 34.817(9) A, β = 98.85(2)° and V = 4535 A3. A single-crystal X-ray diffraction study of I shows that three chelating Se42− ligands provide an octahedral coordination about the central Sn4+ atom. The crystal structure was solved and refined with conventional techniques to R = 6.0% and Rw = 7.0%. The average SnSe distance is 2.709(13) A, while the average SeSe bond distance is 2.324(12) A. The IR spectrum of I (CsI pellet) shows two sets of absorptions at 273, 256 cm−1 and 181, 173 cm−1, respectively, assigned tentatively to ν(SeSe) and ν(SnSe) vibrations. The 119Sn NMR spectrum of I in DMF, shows a single resonance at − 723 ppm (vs Me4Sn). The 77Se NMR spectrum of I in DMF, shows two resonances at 618 and 459 ppm. Thermal decomposition of I results in formation of SnSe2 at 510°C. Further heating, above 600°C, results in SnSe.

Synthesis and characterization of indium thiolates: structures of [Ph4P][In(SBut)4·CH3OH and [Ph4P][In(SCH2CH2S)2]

Abstract Reaction of InCl3 with four equivalents of KSBut in the presence of Ph4PCl gave the monomeric complex [Ph4P][In(SBut)4·CH3OH (1) which crystallized from methanol as colourless hexagonal shaped crystals. Reaction of InCl3 with NaSCH2CH2SNa and Ph4PBr gave [Ph4P][In(SCH2CH2S)2] (2), which readily crystallized from CH3CN as colourless crystals. Both 1 and 2 were shown by X-ray structures to have tetrahedral coordination of indium.

Isolation of a sulphur-rich indium polysulphide complex containing two different Sx2- ligands. Synthesis and structure of [InS10Br]2−

Abstract The reaction of InBr 3 with K 2 S 5 (or K 2 S 4 and K 2 S 6 ) and Ph 4 PBr afforded yellow (Ph 4 P) 2 [In(S 4 )(S 6 )Br] ( I ). Complex I crystallizes in the monoclinic space group P 2 1 / c with a = 14.355(7), b = 17.723(4), c = 20.974(7) A, β = 108.5(1)°, V = 5060.6(4) A 3 (at 23°C), Z = 4. The [In(S 4 )(S 6 )Br] 2− anion features a trigonal bipyramidal indium centre coordinated by four sulphur atoms and one bromine atom. The latter occupies an axial position. The In 3+ centre is chelated by two bidentate polysulphide S 4 2− and S 6 2− ligands. The S 6 2− ligand occupies two equatorial positions. The remaining one equatorial and one axial positions are occupied by the S 4 2− ligand. The average In—S distance is 2.535(35) A. The In—Br distance is 2.615(3) A. Complex I shows no absorptions in the UV-vis spectrum. Two strong absorptions at 490 and 457 cm −1 in the IR spectrum are attributed to S—S vibrations.

Synthesis of [Tl4Se16]4-: a novel tetranuclear Tl3+ polyselenide

Abstract (Ph 4 P) 4 [Tl 4 Se 16 ] was prepared hydrothermally in a sealed pyrex tube by the reaction of TlCl, K 2 Se 4 and Ph 4 PCl in a 1:1:1 molar ratio at 110 °C for one day. The red crystals were obtained in 50% yield. Crystals of (Ph 4 P) 4 [Tl 4 Se 16 ]: triclinic P 1 (No. 2), Z =1, a =12.054(9), b =19.450(10), c =11.799(6) A, α=104.63(4), β=98.86(6), γ=101.99(6)° and V =2555(3) A 3 at 23 °C, 2θ max =40.0°, μ=120.7 cm −1 , D calc =2.23. The structure was solved by direct methods. Number of data collected: 5206. Number of unique data having F o 2 >3σ( F o 2 ): 1723. Final R =0.075 and R w =0.089. [Tl 4 Se 16 ] 4− consists of four, almost already linearly arranged, tetrahedral thallium centers which are coordinated by two chelating Se 4 2− , two bridging Se 2 2− and four bridging Se 2− ligands. [Tl 4 Se 16 ] 4− sits on an inversion center and possesses a central {Tl 2 Se 2 } 2+ planar core. The Tl(1)–Tl(1)′ distance in this core is 3.583(6) A. These two thallium atoms are then each linked to two cyclic Tl(Se 4 ) fragments via bridging Se 2 2− and Se 2− ligands forming Tl 2 Se(Se 2 ) five-membered rings.