Tetraphosphabenzenes Obtained via a Triphosphacyclobutadiene Intermediate

Abstract

An acyl triphosphirene ligand transfers an O atom to Nb to liberate the putative triphosphacyclobutadiene intermediate [RCP3{W(CO)5}2], which engages in [2+4]‐cycloaddition reactions with an organic diene and a phosphaalkyne (see scheme; P orange, O red, W violet, C white). The latter reaction yields the Dewar isomer of a tetraphosphabenzene, which can be converted to a tetraphosphabenzvalene containing a Z‐diphosphene.

Shuttling P3 from Niobium to Rhodium: The Synthesis and Use of Ph3SnP3(C6H8) as a P3− Synthon

“…[1][2][3][4] While it is well documented that a common result of P 4 activation by transition-metal complexes is replacement of a single vertex of the P 4 tetrahedron by an ML n fragment, such cyclo-P 3 complexes were not recognized until recently for their potential as phosphorus transfer agents. 2-6 Accordingly, anionic cyclo-P 3 complexes of niobium have been shown to serve as sources of P 3 3− upon stoichiometric treatment with suitable tripositive electrophiles, including acid chlorides leading to triphosphabutadiene intermediates, 2,3 or AsCl 3 leading to AsP 3 .…”

“…[1][2][3][4] While it is well documented that a common result of P 4 activation by transition-metal complexes is replacement of a single vertex of the P 4 tetrahedron by an ML n fragment, such cyclo-P 3 complexes were not recognized until recently for their potential as phosphorus transfer agents. [2][3][4][5][6] Accordingly, anionic cyclo-P 3 complexes of niobium have been shown to serve as sources of P 3 3− upon stoichiometric treatment with suitable tripositive electrophiles, including acid chlorides leading to triphosphabutadiene intermediates, 2,3 or AsCl 3 leading to AsP 3 . 4,7 With the present work we illustrate a new approach to phosphorus transfer chemistry by way of a P 3 1− synthon, the Ph 3 SnP 3 (C 6 H 8 ) molecule, that is both nucleophilic at phosphorus and capable of losing neutral 1,3-cyclohexadiene upon treatment with an appropriate P 3 1− acceptor.…”

A Phosphorus Analogue of p‐Quinodimethane with a Planar P4 Ring: A Metal‐Free Diphosphorus Source

“…The incorporation of phosphorus atom into p-conjugated frameworks offersu nique opportunitiesf or controlling the properties of derived species. A phosphorus analogueo fp-quinodimethane (pQDM), (IPrC) 2 P 4 [5,I Pr = C{N(Ar)CH 2 } 2 ;A r= 2,6-iPr 2 C 6 H 3 ]f eaturinga planar P 4 ring, was readily accessible by KC 8 -reduction of (IPrC)(PCl 2 ) 2 (2). Base-mediatedC ÀHf unctionalizationo f IPrCH 2 (1)w ith PCl 3 afforded 2.T he formation of 5 was expected to occur through ad imerization of the transient 3H-diphosphirene (IPrC)P 2 (4), which was theoretically suggested to have an intermediate diradical character.C ompound 5 underwentp hoto-induced ring-contraction reaction to form the singlet diradicaloid (IPrCP) 2 VI and white phosphorus (P 4 ).…”

“…Thef ormationo fa nd VI andP 4 suggested the formald iphosphorus( P 2 )e limination from 5. Indeed,p hotolysis of am ixture of 1,3-cyclohexadiene (CHD) and 5 led to the formation of P 2 -entrapped product (CHD) 2 P 2 (6). The compound 5 represents the first organophosphorus speciesthat functions as aP 2 source.…”

“…In 2009, Cummins and co-workersr eported the cyclic bis-phosphaalkene III stabilized by W(CO) 5 moieties. [6] Like benzene, para-quinodimethane (pQDM, A)i s ak ey structural unit in various p-conjugated molecules and materials. [7] The parent pQDM A is however extremelyr eactive and has been studied only at very low temperature.…”