Structure of bis(tetraphenylphosphonium) pentaselenide

Abstract

Abstract. [P(C6Hs)4]2 [Ses], Mr= 1073.6, monoclinic, P2~ (C2), a=9.573 (7), b= 16.945 (12), c= 13.563(10)A, fl=105.29(2) ° , V=2122(3)A 3, z = 2, D x = 1.68 g cm -3, Mo Ko., 2(Kay) = 0.7093 A, /z= 43.8 cm -~, F(000)= 1054.6 including anomalous dispersion, T= 123K, R(F 2)=0.075 for 3681 reflections. The Se 2-chain has a trans conformation with short terminal and long internal Se-Se bonds of average lengths 2.315 (2) and 2.361 (2)A, respectively. The internal and the average terminal Se-Se-Se angles are 110.59 (7) and 108.93 (6) °, respectively. The Se(1) and Se(5)atoms are twisted out of the Se(2), Se(3), Se(4) plane by torsion angles of 77.32 (8) and 89.16 (7) ° , respectively.Introduction. Soluble salts of transition-metal selenium anions [MxS%] 2-are rare. We recently showed that selenation of ammonium metavanadate with bis(dimethyloctylsilyl) selenide produced the V2Se23 ion (Chau, Wardle & Ibers, 1987). As a continuation of our efforts to discover new transition-metal selenium anions we have investigated the reaction of zirconium tetraethoxide with bis(dimethyloctylsilyl) selenide. In an attempt to crystallize the resulting product, we obtained the title compound, presumably as a result of airoxidation of a zirconium selenide anion. Here, we report its molecular structure and compare it with that of other Se 2-anions.

Homoleptic Octahedral Methylamine Complexes of Manganese(II): Solvothermal Syntheses and Crystal Structures of [Mn(NH2CH3)6]Cl2 and the Pentaselenide [Mn(NH2CH3)6]Se5

“…In the CH 3 CN16 and the DMF solvate17 of [Cs(18‐crown‐6)] 2 Se 5 the respective dihedral angles are 0°, indicating perfect cisoid conformation, and with 4° in the structure of [NEt 4 ] 2 Se 5 · Se 6 · Se 7 18 an almost fulfilled cisoid conformation is present. [NEt 4 ] 2 Se 5 19 contains a Se 5 2– chain with a dihedral angle of 126°, Se 5 2– in [PPh 4 ] 2 Se 5 20 shows an angle of 147° and in [Na(15‐crown‐5)] 2 Se 5 it amounts to 179°,21 indicating increasing transoid conformation. The alkaline pentaselenides K 2 Se 5 ,21 Rb 2 Se 5 ,22 and Cs 2 Se 5 23 take an intermediate position with respective dihedral angles of 129°, 127°, and 128°.…”

Organic Cation and Complex Cation‐Stabilized (Poly‐)Selenides, [Cation]x(Sey)z: Diversity in Structures and Properties

“…[45] However, as the authors correctly state, these organoselenium compounds with Se-N bond lengths of 1.836 Å and 1.824 Å respectively, do not comprise salt like ion separation. [Ph 3 PNPPh 3 ] 2 (Se 4 )· 4MeCN [46] (c) and [Mn(MeNH 2 ) 6 ](Se 4 ) [37] (c) are further prominent examples of selenides of category (c), whereas [Li(tmeda) 2 ] 2 (Se 4 ) (tmeda = N,N,NЈ,NЈ-tetramethylethane-1,2-diamine), with Li-Se distances of 2.589 Å to 2.661 Å, [47] [49] The structural deviations due to this association are small -for instance, the mean Se-Se bond length is 2.325 Å as compared to 2.339 Å in (PPh 4 ) 2 (Se 5 ) (c); [50] therefore the classification is done alongside with (NMe 4 ) 2 (Se 5 ) (c), [51] [Na(15-crown-5)] 2 (Se 5 ) (c) (15-crown-5 = 1,4,7,10,13-pentaoxacyclopentadecane), [52] [tdNMe 3 ] 2 (Se 5 ) (c) [td = tetradecyl = (CH 2 ) 13 CH 3 ], [23] again, the latter only characterized by means of elementary analysis, and [Mn(NH 2 CH 3 ) 6 ](Se 5 ) (c). [53] [Li 2 (Se 5 ) 2 (pmeta) 2 ] (b) [54] (pmeta = pentamethyldiethylenetriamine) exhibits mean Se-Li distances of 2.59 Å that are close to the sum of ionic radii, and further elongations of the terminal Se-Se bond also indicate a strong Li-Se interaction.…”

“…[Cs(18‐ crown ‐6)] 2 (Se 5 ) · DMF48 (c) and [Cs(18‐ crown ‐6)] 2 (Se 5 ) · MeCN46 (c) have been reported with well separated anions, as well as (NEt 4 ) 2 (Se 5 ) · (Se 7 ) · (Se 6 ) (c) that contains (Se 5 ) 2– chains and associated six‐ and seven‐membered (Se 6 ) 0 and (Se 7 ) 0 rings 49. The structural deviations due to this association are small – for instance, the mean Se–Se bond length is 2.325 Å as compared to 2.339 Å in (PPh 4 ) 2 (Se 5 ) (c);50 therefore the classification is done alongside with (NMe 4 ) 2 (Se 5 ) (c),51 [Na(15‐ crown ‐5)] 2 (Se 5 ) (c) (15‐ crown ‐5 = 1, 4,7, 10, 13‐pentaoxacyclopentadecane),52 [ td NMe 3 ] 2 (Se 5 ) (c) [ td = tetradecyl = (CH 2 ) 13 CH 3 ],23 again, the latter only characterized by means of elementary analysis, and [Mn(NH 2 CH 3 ) 6 ](Se 5 ) (c) 53. [Li 2 (Se 5 ) 2 ( pmeta ) 2 ] (b)54 ( pmeta = pentamethyldiethylenetriamine) exhibits mean Se–Li distances of 2.59 Å that are close to the sum of ionic radii, and further elongations of the terminal Se–Se bond also indicate a strong Li–Se interaction.…”

Growth of highly nonlinear optical organic crystal, 3-methyl-4-methoxy-4′-nitrostilbene (MMONS)

“…For indexing the natural faces of the MMONS crystal, it is necessary to know the direction of the polar axis without ambiguity because chemically distinct parts of MMONS molecules are revealed on both sides of the polar faces. The anomalous X-ray scattering technique has mostly been used to determine the direction of the polar axis [14,15]. However, if a polar crystal of large size were available, the electrostatic method could also provide a simple and powerful means to differentiate the positive and negative polar faces and, therefore, to determine the direction of the polar axis.…”