Element–Element-Bindungen, IV. Molekül-und Kristallstruktur des Tetramethyldiphosphans und -diarsans /Element–Element Bonds, IV. Molecular and Crystal Structure of Tetramethyldiphosphane and -diarsane

Abstract

The molecular and crystal structures of the isotypic compounds tetramethyldiphosphane 1 and -diarsane 2 have been determined by single crystal X-ray diffraction (monoclinic; C2/m; Z = 2; 1/2: -155/-144 °C\a = 540.6(2)/555.8(2); b = 1131.0(6)/l 136.7(6); c -602.5(2)/612.8(2) pm;β = 97.31(3)/95.24(3)°;P-P 221.2(1)/As-As 242.9(1) pm). In accordance with the crystallographically imposed symmetry 2/m, the molecules adopt antiperiplanar conformation. Their crystal structures are closely related to those of the homologues tetramethyldistibane 3 [1] and -dibismuthane 4 [3]. As found for the latter compounds, the E -E units (E = P, As) are also aligned in linear chains, but the intermolecular E···E contacts (P···P 381/As···As 370 pm) do not allow any extended interaction between molecules, which otherwise would result in thermochromic effects.

Gallium and Indium Arsanido Metalates: Compounds Derived from the Zinc Blende and Wurtzite Structure

“…The two phenyl rings enclose an angle of 80°. The value of the P±P bond length of 221.7(1) pm is typical for diphosphanes [38]. The antiperiplanar conformation is also present in There is no short intermolecular contact in 4 (P1´´´P1b: 406.7(1) pm) as it was observed for the higher homologes Sb and Bi [39].…”

Synthesis of [2]ferrocenophanes containing trivalent diphosphine units

“…The smaller a and b angles of the parallel form suggest that the parallel form is less distorted than the twist form. On the other hand, the smaller C(ipso)ePeP q angle of 99.6 for the twist form is closer to the CePeP angle of 98.30(5) for Me 2 PePMe 2 , which can be regarded as the q angle without steric strain [12], and also close to those of the more common trivalent phosphines [31]. As far as the q angle is concerned, the twist form is considered to be less distorted.…”

“…[Fe{C 5 H 4 P(Ph)(Cr(CO) 5 )} 2 ] (12) [Fe{C 5 H 4 PCl(Ph)} 2 ] (0.098 g, 0.21 mmol) was dissolved in THF (7 mL). The solution was added to a Schlenk tube that was charged with an excess amount of magnesium turnings (1.0 g, 41.2 mmol) activated in advance by vigorous mechanical stirring with a Tefloncoated stirrer bar over 4 h. The reaction mixture was stirred for 4 h, and filtered under a nitrogen atmosphere.…”

“…The angle further increases for diphospha analogs 1a and 1b, and in the dibora analogs 5a and 5b, the strain is the largest, judging from their a and b angles [10b,10f]. If the P(III)eP(III) length of (PR) 2 -bridged [2]ferrocenophane is assumed to be comparable to those of trivalent diphosphines R 2 PePR 2 , for example, 2.212(1) Å of Me 2 PePMe 2 [12], 2.217(1) Å of Ph 2 PePPh 2 [13], and 2.2345(9) Å of t Bu 2 PeP t Bu 2 [14], (PR) 2 -bridged [2]ferrocenophane is anticipated to have a strain comparable to those of 1a and 1b, meaning that they would have a sufficient thermodynamic stability for isolation.…”

[(dme)Li]3As7 – Synthese und Aufbau einer Verbindung mit Nortricyclen-Struktur

“…von 242,2 bis 243,2 pm in der zweiten Gruppe nur geringfu È gig. Eine ebenso deutliche Trennung beobachtet man mit Werten um 250 pm einerseits und 244 pm andererseits auch bei der Bindungsla Ènge g. Zieht man nun noch die am Tetramethyl- [34] und Tetrakis(2,2-dimethylpropionyl)diarsan [35] ro È ntgenstrukturanalytisch ermittelten As±As-Bindungsla È ngen oder die Summe der kovalenten Radien von 242,9 und 241,7 bzw. 242 pm [36] zum weiteren Vergleich heran, so ergibt sich fu È r die Zintl-Anionen eine geringfu È gige bzw.…”