The 1,1,3-tris(diisopropylamino)diphosphirenium salt 1 diphosphirene 9, which can be subsequently converted into the 1-diisopropylamino-, 1-azido, or 1-phenyl-3-diisopro-reacts with lithium aluminium hydride leading to the Phydrogeno-C-phosphinophosphaalkenes 2, which on treat-pylamino-1H-diphosphirenes 6, 10 and 11 by nucleophilic substitution with diisopropylamine, azidotrimethylsilane or ment with a catalytic amount of BF 3 •OEt 2 afford the 1,3bis(diisopropylamino)-1H-diphosphirene 3. The corres-sodium tetraphenylborate, respectively. The [η 2 -(3diisopropylaminodiphosphirenylium salt)•W(CO) 5 ] complexes ponding η 1 -coordinated 1H-diphosphirene 6 can be prepared by treatment of 2 or 3 with one equivalent of 12a-c can be prepared by reaction of 9 with silver trifluoromethanesulfonate, aluminium or gallium trichloride [W(CO) 5 (thf)]. Alternatively, the diphosphirenium salt 1 reacts with an excess of [W(CO) 5 (thf)], affording the or, alternatively, by treatment of 6 with two equivalents of trifluoromethanesulfonic acid. Reaction of 12a with corresponding η 1 -coordinated diphosphirenium salt complex 4, which is converted into the P-hydrogenophosphaalkene diisopropylamine, water, bis(triphenylphosphoranylidene)ammonium chloride or tetrabutylammonium fluoride gives complex 5 with lithium aluminium hydride. The dinuclear tungsten complexes 7 and 8 are obtained by treatment of the the corresponding 1H-diphosphirene complexes 6, 13, 9, or 14, respectively. Compound 12a also reacts with one or two free 1H-diphosphirene 3 with two equivalents of [W(CO) 5 (thf)] or one equivalent of [W(CO) 4 (thf) 2 ], respec-equivalents of [W(CO) 5 (thf)], leading to the di-and trinuclear complexes 15 and 16, respectively. tively. Compound 6 reacts with two equivalents of hydrogen chloride, giving the 1-chloro-3-diisopropylamino-1H-Although no complexes featuring 1H-diazirines B or di-[a] Laboratoire d'He ´te ´rochimie Fondamentale et Applique ´e, Universite ´Paul Sabatier,