Synthesis of 1,1'-bifunctional aminophosphane complexes 3 a-e was achieved by the reaction of Li/Cl phosphinidenoid complex 2 with various primary amines (R=Me, iPr, tBu, Cy, Ph). Deprotonation of complex 3 a (R=Me) with potassium hexamethyldisilazide yielded a mixture of K/NHMe phosphinidenoid complex 4 a and potassium phosphanylamido complex 4 a'. Treatment of complex 3 c (R=tBu) and e (R=Ph) with KHMDS afforded the first examples of K/NHR phosphinidenoid complexes 4 c and e. The reaction of complex 3 c with 2 molar equivalents of KHMDS followed by PhPCl afforded complexes 5 c,c', which possess a P N-ring ligand. All complexes were characterized by NMR, IR, MS, and microanalysis, and additionally, complexes 3 b-e and 5 c' were scrutinized by single-crystal X-ray crystallography.

While 1,2σ5λ5-oxaphosphetanes are well known intermediates from the Wittig-reaction, no 1,2σ3λ3-oxaphosphetanes have been described, so far. Herein, we present the first synthesis of 1,2σ3λ3-oxaphosphetanes derived from their κP-Mo(CO)5 complexes and first investigations towards metal coordination and P-oxidation. Bonding, ring strain energy and potential retro-[2+2] cycloaddition reactions of the 1,2-oxaphosphetane ring were studied by DFT methods.

Synthesis of phosphinite complexes 12-14a-c, 15a and 16a was achieved via reaction of transient Li/Cl phosphinidenoid complexes 6-10, prepared from dichloro(organo)phosphane complexes [(OC)5M{RPCl2}] 1-5 (1,6: R = CPh3, 2,7: R = C5Me5, 3-5, 8-10: R = CH(SiMe3)2, 1-3, 6-8: M = W, 9: M = Mo, 10: M = Cr), with different alcohols 11a-c (a: R = allyl, b: R = methyl, c: R = isopropyl). Deprotonation of complexes 12b, 13b with MeLi or (t)BuLi in the presence of two equivalents of 12-crown-4 led to the selective formation of phosphinidenoid complexes [Li(12-crown-4)2] [(OC)5W{RP(OCH3)}] (18a R = CPh3 and 18b R = C5Me5) which were stable in solution at ambient temperature, in contrast to Li/OMe phosphinidenoid complexes without 12-crown-4. To our surprise attempts to crystallise complex 18b yielded complex 21 having a Li-O-P subunit. The reaction of complex 17c with [Ph3C]BF4 yielded the P-C coupling product 26 and, hence, the first evidence for an oxidative SET reaction. All isolated products were characterised by multinuclear NMR spectroscopy, IR, MS and single-crystal X-ray crystallography in the case of complexes 12a,b, 13b, 14a-c, 15a, 16a and 21.

While P(V) 1,2-oxaphosphetanes are well known from the Wittig reaction, their P(III) analogues are still unexplored. Herein, the synthesis and reactions of the first 1,2-oxaphosphetane complexes are presented, which were achieved by reaction of the phosphinidenoid complex [Li(12-crown-4)(solv)][(OC)5W{(Me3Si)2HCPCl}] with different epoxides. The title compounds appeared to be stable in toluene up to 100 °C, before unselective decomposition started. Acid-induced ring expansion with benzonitrile resulted in selective formation of the first complex bearing a 1,3,4-oxazaphosphacyclohex-2-ene ligand.