1179. The crystal and molecular structure of phosphobenzene A, (PC6H5)5

Abstract

Crystals of phosphobenzene A, m. p. 149-150°, are monoclinic with unit cell dimensions a = 9-742, b = 10.139, G = 27.488 A, p = 90.0". The space group is P21/n. The molecule is pentameric, (PC6H5)5, and contains a fivemembered ring of phosphorus atoms in the form of an equilateral pentagon with approximate symmetry m. To each phosphorus atom is attached one phenyl group. The structure has been refined by the least-squares method using threedimensional intensity data collected on a Hilger and Watts Linear Diffractometer.FOUR polyphosphines of formula (PC6Hs); have been reported.1-9 Of these, two are crystalline: A, m. p. 149-150",1-9 and B, m. p. 190".2~ 3 The other two forms have been presumed to be polymeric.3~8 This paper describes the structure of form A, m. p. of a single crystal recryst allised from acetonitrile 154-1 56" . l o Various molecular weight determinations in solution indicate that n = 2 (refs. 2, 3, 8) or n = 4 (refs. 4, 5, 9); however, in the crystalline state, n = 5, and compound A contains a five-membered ring of phosphorus atoms each of which also carries a phenyl group.lO EXPERIMENTAL C30H25P5.

Conformational stability and ring-size integrity of cyclic polyphosphines

“…The parameters in Table I result from an iterative fit of the line positions; the root-mean-square error for fitting 22 lines is 0.06 Hz. The a Chemical shifts (6) in ppm and coupling constants (J) in Hz. 19 Phosphorus nuclei bonded to the methylene carbon are presumed to be "A" spins since ~J A A I << IJBBI, implying that B and B' are directly bonded.…”

A Masked Phosphinidene Trapped in a Fluxional NCN Pincer

“…[19, 20d] Compound 1 differs from its previously reported Sb and Bi analogues C and D in which the symmetrical C 2v structure is the ground state; [14] our DFT calculations confirm the symmetrical structures for these heavier congeners, but indicate the corresponding As derivative also has an unsymmetrical ground state with as ymmetrical transition state only 2.1 kcal mol À1 higher. [22] While the significantly longer C17ÀN2 bond (1.350 (4) )c ompared to unboundi mine C6ÀN1 (1.287(4) )i sc onsistentw ith this idea, [22] as hort C17ÀC19 distance (1.403 (4) )c ompared to C8ÀC19 (1.436 (3) )a nd aP 1 À C8 bond (1.744 (3) )i ntermediate between aP ÀCs ingle [23] and double bond are not expected. [22] While the significantly longer C17ÀN2 bond (1.350 (4) )c ompared to unboundi mine C6ÀN1 (1.287(4) )i sc onsistentw ith this idea, [22] as hort C17ÀC19 distance (1.403 (4) )c ompared to C8ÀC19 (1.436 (3) )a nd aP 1 À C8 bond (1.744 (3) )i ntermediate between aP ÀCs ingle [23] and double bond are not expected.…”

Synthese und Molekülstruktur von [Li(THF)4][{(CO)4Mo}2(μ-PPh2)(μ-PPh2PPh2)]: Die erste Verbindung mit einem 1,3-Dimetalla-cyclopentaphosphan-Gerüst

“…P±P in (PPh 5 ) 5 : 2,217(6) A Ê [28]). Vergleichbar groûe P±P-Bindungsla È ngen wurden auch in anderen Diphosphan-Komplexen beobachtet ([(CO) 3 Ni(l-PPh 2 PPh 2 ) 2 Ni(CO) 3 ]: P±P 2,277(4) A Ê [29], [(CO) 5 Cr(l-PPhClPPhCl)Cr(CO) 5 ]: 2,290(1) A Ê (meso), 2,327(6) A Ê (rac) [30]).…”