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tert‐Butylthiophosphinidene complex [tBuSP‐W(CO)5] was generated by dissociation of 1‐(tert‐butylthio)phosphirane–W(CO)5 complex under mild conditions. The formation of transient [tBuSP‐W(CO)5] was indicated by trapping reactions with 2,3‐dimethyl‐1,3‐butadiene, alkynes, phenanthrene‐9,10‐dione, and methanol. The LUMO of [MeSP‐W(CO)5] is significantly lower in energy than those of [Me2NP‐W(CO)5], [MeOP‐W(CO)5], and [Me2PP‐W(CO)5]. The HOMO of [MeSP‐W(CO)5] contains a significant contribution from the in‐plane lone pair of P and the LUMO shows a typical π* characteristic. Since stabilized by sulfur lone pair and coordinated by W(CO)5, [tBuSP‐W(CO)5] undergoes facile and reversible cycloadditions with alkenes and alkynes. [ABSTRACT FROM AUTHOR]

Nucleophilic substitution results in inversion of configuration at the electrophilic carbon center (SN2) or racemization (SN1). The stereochemistry of the nucleophile is rarely considered, but phosphines, which have a high barrier to pyramidal inversion, attack electrophiles with retention of configuration at P. Surprisingly, cyclization of bifunctional secondary phosphine alkyl tosylates proceeded under mild conditions with inversion of configuration at the nucleophile to yield P‐stereogenic syn‐phosphiranes. DFT studies suggested that the novel stereochemistry results from acid‐promoted tosylate dissociation to yield an intermediate phosphenium‐bridged cation, which undergoes syn‐selective cyclization. [ABSTRACT FROM AUTHOR]

method for the preparation of three-membered phosphoric heterocycles--phosphi-ranes by reaction of dilithium derivatives of tertiary phosphines with tetrachloromethane is described. The reaction is stereoselective and leads to the formation of anti-cis(meso)-2,3-diphenylphosphiranes. Phosphiranes were isolated as individual compounds and their structure was confirmed by ¹, 13, and 31 NMR spectra, and mass spectra. The present method is simple and can be successfully used for the preparation of some types of phosphiranes that are inaccessible by other methods. [ABSTRACT FROM AUTHOR]

Aluminum trichloride catalyzes the ring opening of a 1-chlorophosphirane W(CO)5 complex and its reaction with thiophene and ferrocene to give the corresponding 1-(2-thienyl)- and 1-ferrocenylphosphirane derivatives. The W(CO)5 complex of the 1-ferrocenylphosphirane is an efficient precursor of the phosphinidene complex [FcP-W(CO)5], which is trapped by tolan, trans-stilbene, and water. [ABSTRACT FROM AUTHOR]

Abstract: Reaction pathways for the formation of zirconocene phosphinidene complex Cp2Zr(PR3)p2ZrCl2 and LiH and LiPRH and its reactivity to 1,2-dichloroethane are explored with density functional theory using model structures that are devoid of substituents. After the initial Cp2Zr(Cl)PH2 is generated with LiPH2 reaction with LiH is likely to eliminate HCl in a single step to give directly the 16-electron complex Cp2Zr is stabilized by the PH3 phosphine ligand. The intermediate formation of a phosphine hydride complex, Cp2Zr(H)PH2 resulting from hydride substitution, is unlikely both on the basis of unfavorable reaction energies and calculated 31P NMR chemical shifts that indicate that such a species cannot have been observed experimentally. It is likely that a diphosphine complex, Cp2Zr(PH2)2, results on using an excess of the lithium phosphide, which on H-transfer gives directly the phosphine-stabilized phosphinidene complex. The reactivity of this species is dominated by the release of its stabilizing phosphine ligand to give a highly reactive 16-electron phosphinidene complex, Cp2Zr reacts with 1,2-dichloroethane after coordination to one of the chlorine atoms in two asynchronous metathesis steps to the three-membered phosphirane ring. In this process, ZrCl2 is reformed enabling its recycling to regenerate the phosphinidene complex. This study highlights the special reactivity of the 16-electron Cp2Zrggests that related complexes may be generated similarly, thereby expanding the synthetic potential of these nucleophilic reagents. [Copyright &y& Elsevier]

BABAR-Phos is a very stable polycyclic phosphirane which is easily synthesized in few steps from dibenzosuberenone. BABAR-Phos is remarkably stable and is not oxygenated with O2 nor does it react with sulfur in boiling toluene. BABAR-Phos can be used as a ligand in homogenous catalysis. Substituents at the carbon of the PC2 heterocycle can be introduced and asymmetric BABAR-Phos were prepared. The coordination chemistry of rhodium complexes containing these as ligands was investigated.

BABAR-Phos is a very stable polycyclic phosphirane that readily forms complexes with rhodium and platinum. Depending on the oxidation state and further co-ligands, either phosphirane complexes or metallaphosphetanes (as products of a metal insertion) prevail. However, these insertion reactions are reversible. These rhodium BABAR-Phos complexes are active catalysts for the selective hydroboration of olefins. [ABSTRACT FROM AUTHOR]

The dibenzo[a,d]cycloheptatrienyl residue is introduced as platform for the high-yield synthesis of new rigid phosphanes (tropp ligand system) and phosphiranes (BABAR-phos); strained three-membered heterocycles. With tropp as ligands, transition metal complexes with unusual low oxidation states at the metal center could be prepared and isolated. Especially mononuclear paramagnetic rhodium(O) and iridium(O) complexes could be studied in detail. The BABAR-phos compounds show very high thermal and chemical stability, i.e. they are remarkably stable against oxygen, sulfur, strong alkylating agents, and aqueous acid and base. Rhodium(l) complexes with BABAR-phos proved to be highly stable active catalyst precursors for hydroborations.

The bis-condensation of [MeP-W(CO)5] with 3-methyl-1,2-butadiene yields two stereoisomers of the corresponding 1,4-diphosphaspiropentane, one of which has been characterized by X-ray crystal structure analysis. [Copyright &y& Elsevier]

tert-Butylthiophosphinidene complex [tBuSP-W(CO) 5 ] was generated by dissociation of 1-(tert-butylthio)phosphirane-W(CO) 5 complex under mild conditions. The formation of transient [tBuSP-W(CO) 5 ] was indicated by trapping reactions with 2,3-dimethyl-1,3-butadiene, alkynes, phenanthrene-9,10-dione, and methanol. The LUMO of [MeSP-W(CO) 5 ] is significantly lower in energy than those of [Me 2 NP-W(CO) 5 ], [MeOP-W(CO) 5 ], and [Me 2 PP-W(CO) 5 ]. The HOMO of [MeSP-W(CO) 5 ] contains a significant contribution from the in-plane lone pair of P and the LUMO shows a typical π* characteristic. Since stabilized by sulfur lone pair and coordinated by W(CO) 5 , [tBuSP-W(CO) 5 ] undergoes facile and reversible cycloadditions with alkenes and alkynes., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)