Annette Ostrowski

Synthesis and Spectroscopic Data ofpara-Substituted (3-Phenyl-2H-azaphosphirene)tungsten Complexes

High-yield synthesis of para-substituted pentacarbonyl(3-phenyl-2H-azaphosphirene)tungsten complexes is reported, using a multi-step rearrangement reaction. Spectroscopic and mass-spectrometric data of these heterocyclic complexes are discussed; the 31P-NMR-chemical shifts clearly reflect the electronic influence of the para-phenyl substituents and the correlation with Hammett σp-constants is almost linear.

Syntheses, Structures, and Reactions of C-Methoxycarbonyl-Functionalized Small- and Medium-Sized P-Heterocycle Complexes

Thermal ring-opening of [{2-bis(trimethylsilyl)methyl-3- phenyl-2H-azaphosphirene-ĸP}pentacarbonyltungsten(0)] (8a) in the presence of dimethyl acetylenedicarboxylate (DMAD) led to the 2,3-bifunctionalized 1H-phosphirene complex 9a and the 4-phenyl-substituted 2H-1,2-azaphosphole complex 10a, the latter as a by-product. If a small amount of benzonitrile was added, complex 10a was obtained as the main product, along with a small amount of the decomplexed 2H-1,2-azaphosphole 11, which could not be isolated. Reaction of complex 10a with elemental sulfur furnished the corresponding PV sulfide 13. When the ring-opening of complex 8a was performed in the presence of two equivalents of DMAD and two equivalents of dimethyl cyanamide, we obtained the 4-dimethylamino-substituted 2H-1,2-azaphosphole complex 10b, together with the diastereomeric Δ3-1,3,2-oxazaphospholene complexes 14a,b. On reaction of [{2-pentamethylcyclopentadienyl-3-phenyl-2H-azaphosphirene-ĸP}pentacarbonyltungsten(0)] (8b) and DMAD in toluene, the corresponding 1H-phosphirene complex 9b was only formed as a transient species and the P-coordinated P,C-cage compound 15 was the final product. Using benzonitrile as solvent, the 4-phenyl-substituted 2H-1,2-azaphosphole complex 10c was obtained, together with the 7-aza-1-phosphanorbornadiene complex 16, the latter through partial decomposition of 10c coupled with rearrangement and a Diels–Alder reaction; the ratio 10c/16 was found to depend strongly on the molar ratio of complex 8b to DMAD. A cycloaddition reaction of the 2,3-bifunctionalized 1H-phosphirene complex 9a with 2,3-dimethylbutadiene furnished the bicyclic phosphirane complex 19, along with a small amount of the noncoordinated bicyclic phosphirane 20. Reaction of complex 9a with diethylamine yielded the phosphirane complex 21 as a 1,2-addition product, the diorganophosphane complex 22 through ring-opening of 9a, and the 3,4-functionalized 1,2-dihydro-1-phosphet-2-one complex 23 through an unprecedented ring-expansion reaction; the products 21, 22, 23 were formed in a ratio of ca. 1:1:1. The structures of the 1H-phosphirene complex 9a, the 4-dimethylamino-substituted 2H-1,2-azaphosphole complex 10b, the bicyclic phosphirane complex 19, the phosphirane complex 21, and the 1,2-dihydro-1-phosphet-2-one complex 23 have been determined by single-crystal X-ray diffraction analysis.

Easy access to C,C′-bifunctionalized 1H-phosphirene–tungsten complexes: evidence for ambiphilic reaction behaviour of a phosphanediyl–tungsten complex

The 2H-azaphosphirene–tungsten complex 1 reacts with ethoxyacetylene 2a or dimethyl acetylenedicarboxylate 2b to yield C,C′-bifunctionalized 1H-phosphirene–tungsten complexes 4a,b; compounds 4a,b are characterized by NMR spectroscopy (13C, 31P) and complex 4a by single-crystal X-ray diffraction.

Advances in 2H-Azaphosphirene Complex Chemistry

Abstract: Synthesis of a wide variety of 2H-azaphosphirene pentacarbonyl metal complexes is reported. The overall reaction of this heterocyclic synthesis was determined to be stereospecific, but no asymmetric induction has been observed. Generation, decomposition and trapping reactions of nitrilium phosphane ylide complexes, a zwilterionic acyclic isomer of 2H-azaphosphirene complexes possessing a novel 1,3-dipole system, are presented.

RECENT RESULTS ON SYNTHESIS AND RING CLEAVAGE REACTIONS OF 2H-AZAPHOSPHIRENE DERIVATIVES

Abstract Reactions of [amino(aryl)carbene](pentacarbonyl)metal complexes with chlorophosphane derivatives under basic conditions yield 2H-azaphosphirene complex derivatives. Investigations of thermally induced ring-cleavage reactions of 2H-azaphosphirene tungsten derivatives in the presence of various trapping reagents are presented.