An Efficient Photochemical Route Towards Triplet Ethynylphosphinidene, HCCP.

While the archetypal free phosphinidene, H-P, has been studied for over a century, reports on uncomplexed, univalent phosphorus compounds are very sparse. Here we demonstrate production of HCCP in solid argon through the UV-induced rearrangement and subsequent dehydrogenation of phosphapropyne, CH3 CP. Migration of H atoms along the CCP backbone of CH3 CP resulted in production of the previously unobserved species 1-phosphapropadiene, CH2 =C=PH, followed by ethynylphosphine, HCCPH2 .