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S Bobev

Publications and source records attributed to S Bobev.

4 recordsLinked to original sources
PubMed2001

Synthesis and characterization of the largest isolated clusters of tin, [Sn12](12-), in (AE)Na10Sn12 (AE = Ca or Sr).

Reported are two isostructural Zintl compounds, CaNa(10)Sn(12) and SrNa(10)Sn(12), with mixed alkali and alkaline-earth cations and isolated clusters of Sn(12)(12-) with the shape of giant truncated tetrahedra. The compounds were synthesized by heating the corresponding mixtures of elements at 950 degrees C. The structures were solved and refined from single-crystal X-ray diffraction data in the cubic space group I43m (No. 217), where Z = 2 with a = 11.1847(6) and 11.2176(4) A for CaNa(10)Sn(12) and SrNa(10)Sn(12), respectively. Both compounds are diamagnetic and therefore electronically balanced.

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PubMed2000

Synthesis and characterization of A3Na10Sn23 (A = Cs, Rb, K) with a new clathrate-like structure and of the chiral clathrate Rb5Na3Sn25.

Four new compounds Cs17.4(1)Na60.6(1)Sn138 (1), Rb19.1(1)Na58.9(1)Sn138 (2), K21.3(1)Na56.7(1)Sn138 (3), and Rb20Na12Sn100 (4) were synthesized by fusion of the corresponding elements. The structures were determined by single-crystal X-ray diffraction. Compounds 1-3 are isostructural and crystallize in a new structure type (rhombohedral, R3m, Z = 1, a = 12.4567(9) A, c = 51.533(3) A for 1; a = 12.465(1) A, c = 51.085(3) A for 2; a = 12.456(2) A, c = 50.559(4) A for 3). The structure contains layers of fused pentagonal dodecahedra of tin that alternate with layers of isolated tin tetrahedra. It is an intergrowth between the structure of clathrate-II (A24Sn136) with the same layers of pentagonal dodecahedra and the Zintl phase ASn with Sn4(4-) tetrahedra. Compound 4 is a new chiral clathrate (cubic, P4(1)32, Z = 1; a = 16.4127(7) A) with stoichiometry that corresponds to an electronically balanced Zintl phase.

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PubMed2000

arachno-

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