Cationic phosphorus–carbon–pnictogen cages isolobal to [C5R5]+

Abstract

The cationic cages nido-[C2Bu(t)2P2E]+ (E = As, Sb), which are isolobal to the cyclopentadienyl cation, adopt square based pyramidal structures with the heavy pnictogen atom at the apex; NMR and computational methods have been used to probe the dynamic behaviour of the complexes.

Electronic Structure and Bonding in Neutral and Dianionic Boradiphospholes: R′BC2P2R2 (R=H, tBu, R′=H, Ph)

“…The nido geometry is a minimum in the H n C n P 5− n + series (in which n >0 has P in the capping position)22 and is observed in 3‐hydroxyhomotetrahedrane derivatives19c of Cp + . In the case of BC 2 P 2 H 3 the BH cap is found to be the lowest energy isomer, with the adjacent carbons in the basal ring (thermodynamic product) 22. The tricyclopentane structure ( 20 a ), found experimentally as 10 , is unstable for the Cp + and carbaphosphole analogues.…”

“…Other partially substituted compounds such as 3,5‐ t Bu 2 ‐1,2,4‐C 2 P 3 + , as well as the isoelectronic cationic arsena‐ and stibolyl‐heterodiphospholes 6 and neutral stanna‐, germa‐ and plumba‐diphospholes 7 also exhibit a nido structure. All these compounds are readily obtained from a zirconocene 1,3‐diphosphabicyclo[1.1.0]butane complex, [ZrCp 2 t Bu 2 C 2 P 2 ], upon treatment with the appropriate trihalide and the Lewis acid AlCl 3 22–24. The presence of P atoms stabilising a cluster‐type ground‐state geometry appears to be a common feature of the isolobal substitution of P for CH,21c as well as for other isolobal connections such as BH − and CH in the carborane clusters 8 ,25 and the heavier Group 14 elements Sn, Ge and Pb 7 23, 24.…”

A Main‐Group Analogue of Housene: The Subtle Influence of the Inert‐Pair Effect in Group 15 Clusters

“…Although the envelope structure of 3 was unexpected in light of our previous work on the tricyclic compounds C 2 tBu 2 P 2 ECl (E = P, As), [5] it is a relatively well-known structural motif, most notably in the hydrocarbon species bicyclo[2.1.0]pent-2-ene (housene) [11] and its triphosphaderivative, 1,2-(CH(SiMe 3 ) 2 )P-1,3-P 2 (CtBu) 2 . [12] Despite the apparent isomorphism of these three compounds, the inward tilt of the apical SbCl fragment noted above is conspicuously absent in the other two species.…”

“…SbCl 3 , because this particular reaction could provide selective access to the nido-SbP 2 C 2 cation [5] and the cyclic 1-Sb-3,4-P 2 C 2 anion. [6] In the event the reaction proceeded in an unexpected and interesting way to form the envelope compound 3 (Scheme 1), which exhibited unusual solid-state and solution-phase behavior.…”

Der Zugang zu Phosphor‐reichen Zirconiumkomplexen

“…[2] Wenn man dieses Gebiet näher betrachtet, erkennt man, dass die P-haltigen Übertragungsreagentien auf frühe Entwicklungen von Binger und Regitz zurückgehen, die im Jahr 1987 den Diphosphabicyclobutan-Zirconiumkomplex A durch die Reaktion von "Cp 2 Zr" mit tBuCP erhielten. [3] Unter Halogenierungsbedingungen nutzten sie A als Ausgangsverbindung zur Synthese beispielloser Moleküle wie Tetraphosphacuban [4] und zahlreicher P,C-Käfigverbindun-gen. [5,6] + (E = P, As), [8][9][10] unerwarteten neutralen P,C- [11] und P,C-Heteroelementkäfigen, [12] um ungewçhnliche Reaktionswege zu Triphospholylanionen zu finden. [13,14] Im Unterschied dazu ist das All-Phosphoranalogon von A, der Tetraphosphabicyclobutan-Komplex C, der bereits 1988 von Scherer et al synthetisiert wurde, [15] [17] Der Bildungsweg von 2 ist unklar, aber es ist mçglich, dass 1 eine P 2 -Einheit eliminiert und der gebildete ungesättigte Zirconiumkomplex mit tBuC P reagiert, um 2 zu ergeben.…”