Scott B. Clendenning

Reaction of a complexed phosphinidene with 2,4,6-tri-tert-butyl-1,3,5-triphosphabenzene.

The terminal phosphinidene complex PhPW(CO)5 reacts with 2,4,6-tri-tert-butyl-1,3,5-triphosphabenzene to give two unexpected multicyclic organophosphorus compounds. One of them results from an initial 1,2-addition, followed by an intramolecular rearrangement. B3LYP/6-31G* calculations on simplified parent systems suggest that the reaction follows a unique concerted reaction pathway. The second, and major, product is a tetraphosphaquadricyclane derivative, which presumably results from an intramolecular [2+2] cycloaddition of an intermediate tetraphosphanorbornadiene complex. Single-crystal X-ray structures are presented for both products.

[1+4]-Cycloadditions of silylenes to 2,4,6-tri-tert-butyl-1,3,5-triphosphabenzene

2,4,6-Tri-tert-butyl-1,3,5-triphosphabenzene 1 undergoes [1 + 4]-cycloaddition with the stable bis(amino)silylenes Si[(NCH2But)2C6H4-1,2] 3, Si[(NBut)2C2H2] 4 and Si[(NBut)2C2H4] 7 to afford the structurally characterised 5, 6 and 11. The intermediate aminosilylsilylene resulting from the dissociation of the disilene [Si{(NBut)2C2H4}]49 was trapped as its [1 + 4]-cycloadduct with 1, nwhich was also structurally characterised. The reversibility of the cycloaddition was demonstrated for 5 through reaction with [Mo(CO)4(nbd)] to afford [Mo(CO)3(η6-P3C3But3)] (13) and a mixture of cis- (14a) and trans-[Mo(CO)4(3)2] (14b) of which 14b has been structurally characterised by a single crystal X-ray diffraction study.

Remarkable carbene-induced transformation of 2,4,6-tri-tert-butyl-1,3,5-triphosphabenzene, P3C3But3, to the 1,2,4-triphosphole, P3C2But2CBut(carbene). Crystal and molecular structure of the planar triphosphole complex [Mo(CO)3(η5-P3C2But2CBut(carbene))] [carbene = C(N(Me)C(Me)=C(Me)N(Me))]

Treatment of 2,4,6-tri-tert-butyl-1,3,5-triphosphabenzene, P3C3But3, with the stable carbene 1,3,4,5-tetramethylimidazol-2-ylidene affords the planar 1,2,4-triphosphole, P3C2But2CBut(carben e), [carbene = C(N(Me)C(Me)C(Me)N(Me))] which has been structurally characterised as its η5- ligated [Mo(CO)3] complex; theoretical calculations are presented on the mechanism of this novel reaction.

A comparison of C3R3P3 and C6R3H3 as ligands using photoelectron spectroscopy and density functional theory

Photoelectron spectra have been recorded for [M(CO)3(η6-C3But3P3)] (Mxa0=xa0Cr, Mo or W) and [Mo(CO)3(η6-C3But3H3)]. They are assigned by comparison with analogous spectra and density functional calculations. The phospha-arene complexes show a higher first IE than carbocyclic analogues. Electronic structure analysis indicates stronger bonding in the former as a result of greater metal–ligand back donation to the lower lying LUMOs of the P substituted ring.

First η1-ligated 2,4,6-tri-tert-butyl-1,3,5-triphosphabenzene complexes and the remarkable trihydration reaction of trans-[PtCl2(PMe3)(P3C3But3)] to cis-[PtCl(PMe3)(P3O3C3H5But3)], containing the novel CH(But)PH(O)C(But)PH(O)CH(But)P(O) ring system

The first examples of η1-complexes of 2,4,6-tri-tert-butyl-1,3,5-triphosphabenzene are described, namely trans-[PtCl2(PR3)(P3C3But3)] (PR3 = PMe3, PEt3, PMe2Ph or PMePh2) and their structures established by 31P and 195Pt NMR spectroscopy. The unusual molecular structure of cis-[PtCl(PMe3)(P3O3C3H5But3)], containing the novel CH- (But)PH(O)C(But)PH(O)CH(But)P(O) ring system, which is formed by the trihydration of trans-[PtCl2(PMe3)(P3- C3But3)] is also reported.

[1 + 4]-Cycloaddition of a stable silylene to 2,4,6-tri-tert-butyl-1,3,5-triphosphabenzene

The stable bis(amino)silylene Si[(NCH2But)2C6H4-1,2] 1 undergoes [1 + 4]-cycloaddition with 2,4,6-tri-tert-butyl-1,3,5-triphosphabenzene 2 to afford compound 3: the molecular structure of 3 is supported by NMR spectroscopic data and confirmed by a single crystal X-ray diffraction study.