Nils Hoffmann

SYNTHESES, STRUCTURES AND REACTIONS OF NEW AND NOVEL FOUR-, FIVEAND SIX-MEMBERED UNSATURATED N,P-HETEROCYCLE COMPLEXES

Metal-assisted heterocyclic ligand syntheses are reported using 2-H-azaphosphirene complex 1 or 7-phosphanorbornadiene complex 7 as starting material. Thermal decomposition of complex 1 led to 1,2dihydro-1,2,3-azadiphosphete complex 2, which was transformed into 2,6-dihydro-1,3,2,6-diazadiphosphinines 5a, b via ring expansion with carbonitriles 3a, b. Insertion of tert-butyl isonitrile into the P─ P bond of 2 at ambient temperature furnished the first Δ 1 -1,3,5-azadi-phospholene complex 6─P bond of 2 using 7 failed. The 1,2,3,4-azatriphospholene complexes 9a, b were obtained by thermolysis of complex 2 in the presence of functionalized carbonitriles 8a, b.

Synthesis of the first 1,2,3,4-azatriphospholene complex

Synthesis of the first 1,2,3,4-azatriphospholene complex was achieved by heating a solution of a P-phenyl-substituted 7-phosphanorbornadiene tungsten complex and triphenylphosphonio cyanomethylide, whereby CH-insertion products were formed in a competing reaction; these results also provide first evidence for the ability of electrophilic terminal phosphanediyl complexes to react at the ylide carbon atom and at the carbonitrile nitrogen atom of Wittig-ylides having a nitrile functional group; the structures of both complexes were established through X-ray single-crystal diffraction studies.

Strong evidence for stereoselective 1,3-additions of transient nitrilium phosphane-ylide complexes: synthesis of the first 1-aza-3-phosphabuta-1,3-diene complexes

Synthesis of the first 1-aza-3-phosphabuta-1,3-diene complexes was achieved by heating solutions of 2H-azaphosphirene tungsten complexes, 1-piperidinonitrile and [bis(trimethylsilyl)methylene]chlorophosphane; X-ray structure analysis of one new complex revealed a cisoid position of the chlorine atom and the phosphaalkene unit at the C,N,P-core of the trapped nitrilium phosphane-ylide complex and a distorted heterobutadiene π-system.