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

Abstract
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.