Electron distribution in tert-butyl phosphaethyne Bu^tCP

Abstract

The first high-precision, low-temperature, X-ray diffraction study o n a phosphaalkyne reveals that the lone pair electrons are located much closer to the P atom than in the related phosphaalkene, and furthermore there is a significant excess electron density o n the sp-hybridised C atom, thus readily accounting for the remarkable preferential protonation at C rather than at P i n spite of the presence of the lone-pair electrons.

Phospha‐Organic Chemistry: Panorama and Perspectives

“…As expected the P C bond of tBuC P is very short at 1.548(1) . [75] When Gier discovered phosphaacetylene HCP in 1961, [76] the long-term impact of this discovery was not fully realized by the chemical community. [77] provided support for the pioneering work of Gier, but it was only in 1981 with the work of Becker et al that the chemistry of phosphaalkynes was firmly established [Eq.…”

Ring Expansion of a Cp* Moiety: Formation of a 1,2‐Diphosphacyclooctatetraene Ligand

“…According to our ab initio calculations on the MP2/ TZVPP level, no significant differences in the triple-bond character and the charge distribution are found (see the Supporting Information). [25] However, in MesC P, by conjugation with the aromatic p system, the HOMO is increased in energy by 1.8 eV and the LUMO is decreased by about 1 eV, which indicates better donor as well as acceptor properties of MesCP in comparison with tBuCP. Thus, for the formation of 6, although an initial end-on coordination of the phosphaalkyne at the phosphinidene P atom in 1 can not be excluded (examples of end-on coordination of a phosphaalkyne [26] and of a nitrile [27] to the central P atom in 1 have been reported; for an alternative mechanism that starts with this type of coordination to form 6, see the Supporting Information), we would propose a side-on coordination of MesC P at the tungsten carbonyl moiety after CO elimination.…”

Zur Reaktion vontert-Butyl-phosphaalkin mit Molybdänkomplexen

“…Die Struktur von 1 entspricht der von Binger fu È r das Produkt der Reaktion (2) beschriebenen [6]. Die P±C-Absta È nde im 1,3-Diphosphacyclobutadienylring [177,1(6) pm±179,7 (6) pm] liegen zwischen den Werten fu È r eine P±C-Einfachbindung und eine P=C-Doppelbindung [d(P±C) = 184 pm [7]; d(P=C) = 169 pm in R 2 C=PR' [8]; d(P≡C) = 154 pm in tBuC≡P [9]]. Das p-Elektronensystem sollte somit delokalisiert sein.…”

“…0,3014 (6) ±0,0651 (12) 0,034(6) C (5) 0,5568(11) 0,2421 (5) ±0,0954(9) 0,028(5) C (6) 0,7232(11) 0,0581(5) 0,1615(9) 0,036(5) C (7) 0,8164 (11) 0,0633 (5) 0,2332 (9) 0,027(5) C (8) 0,6391 (15) 0,0064 (6) 0,1923 (12) 0,032(5) C (9) 0,7738 (15) 0,0407 (6) 0,0740 (11) 0,024(4) C (10) 0,4802 (1) (20) 0,3954(12) 0,4725 (5) 0,1094(9) 0,033(2) C (21) 0,3485(9) 0,5188(3) 0,1019 (7) 0,038(3) C (22) 0,1662 (11) 0,3198 (5) 0,1333 (8) 0,056(4) C (23) 0,1959(11) 0,1922(5) 0,1299 (9) 0,058(4) C (24) 0,1039 (13) 0,3838 (5) 0,1329(10) 0,040(3) C(25) 0,1253 (13) 0,4173 (5) 0,0436 (9) 0,041(3) C(26) 0,1397 (15) 0,4246 (6) 0,2123 (11) 0,060(4) C (27) ±0,0231 (15) 0,3733 (7) 0,1423 (13) 0,067(4) C(28) 0,1517 (11) 0,1226 (5) 0,1351 (9) 0,029(2) C(29) 0,1224 (17) 0,1075 (7) 0,2223 (12) 0,069(4) C(30) 0,2481 (15) 0,0760 (7) 0,1027 …”