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.

Syntheses of 1,1′-bifunctional aminophosphane complexes 3–10 was achieved by reacting Li/Cl phosphinidenoid complex 2 (R = CPh3) with secondary (Me2NH, Et2NH, Bn2NH, pyrrolidine, and piperidine), primary amines (EtNH2 and allyl amine), and ammonia. Furthermore, regioselective N-silylation of 11 (R = Me) was achieved using MeLi and Me3SiCl to give complex 12. In contrast, treatment of complex 6 with KHMDS in the presence of 18-crown-6 yielded K/NMe2 phosphinidenoid complex 13 subsequently reacted with MeI to give P–Me substituted 14. Complex 5 was deprotonated with KHMDS in the presence of 18-crown-6 and reacted with [Ph3C]­BF4 to yield complex 17 via single-electron transfer reaction and P,C-heterocoupling. Finally, selective P–N bond cleavage was achieved by treating complex 18 (R = t-Bu) with HCl­(g) to afford chlorophosphane complex 19.

The synthesis of 1,2-oxaphosphetane complexes and 1,2-oxaphospholane complex bearing only substituents at phosphorus is reported using the reaction of Li/Cl phosphinidenoid complex with 2-iodoethanol or 3-bromo-propane-1-ol and the subsequent dehydrohalogenation using KHMDS. In contrast, the reaction of complex with (t)BuLi leads selectively to the formation of phosphinito complex .

The first example of a ring opening reaction of a 1,2-oxaphosphetane complex is reported, i.e., water in the presence of [Li(12-crown-4)]Cl furnished a C-OH functional phosphinito complex. Employment of the latter in ring forming reactions with MeECL (E = Si, Ge) using different nitrogen bases is also described.

b S Supporting Information S piroalkanes such as spiropentanes (I) have been intensively studied by experimentalists as well as theoreticians. 1 Although spiroheterocycles are present in a large number of natural products 2 and show physical properties of particular interest, 3 the area of phosphorus-containing spiroheterocycles is deeply underdeveloped and, moreover, the research has been focused on phosphorusÀcarbon ring systems 4 such as the phospha-spiropentanes IIÀIV (Scheme 1). Whereas most derivatives of II 5,6 and III 7 were bound to a transition-metal center, 8 the only known derivative of IV 9 (all tert-butyl substituted) was obtained nonligated. To the best of our knowledge, nothing is known about spiroheterocycles that have another heteratom (as in V) and, therefore, the question of the effect of a (very) polar ring bond on structure and reactivity has not been addressed before.Theoretical investigations on monocyclic oxaphosphirane derivatives revealed a considerable ring strain of 23.2 kcal/mol for the parent system (RI-CCSD(T)/TZVPP), while for trimethyloxaphosphirane pentacarbonylchromium(0) a slightly smaller mean value of 22.0 kcal/mol was obtained (RI-SCS-MP2/ TZVPP); 10 this transition-metal effect was not studied further. Recent experimental studies on acid-induced ring opening 11 of monocyclic oxaphosphirane complexes have demonstrated that they have become valuable new building blocks which deserve further study. On the basis of the convenient methodology for oxaphosphirane complexes that was developed recently, 12 we felt attracted by the idea to establish a method that enables access to spiroheterocycles of type V as new ligand systems, which have various ring sizes and various heteroatoms E.Here, we report the facile synthesis of the first spirooxaphosphirane complexes (E = O) using the Li/Cl phosphinidenoid complex route and cyclic ketones. Furthermore, a first attempt to access a phospha-spiropentene complex derivative using this particular route is described. ' RESULTS AND DISCUSSIONChlorine/lithium exchange in complex 1, 13 using tert-butyllithium in the presence of 12-crown-4 at low temperature, led to the transient Li/Cl phosphinidenoid complex 2, 12a which was reacted in situ with cyclohexanone, cyclopentanone, and cyclobutanone, thus yielding the spirooxaphosphirane complexes 3a,bÀ5a,b (Scheme 2).In all reactions the two isomers a and b were formed (3a,b, 23:77; 4a,b, 55:45; 5a,b, 69:31; determined via integration of the 31 P{ 1 H} NMR spectra); only in the case of complexes 3a,b was the major isomer the b isomer, while in all other cases (4a,b and 5a,b) was the minor isomer. Column chromatography yielded only isomer 3b in pure form (see below), while the other complexes could not be separated and thus were purified and characterized as mixtures. Despite this, the structures of complexes 4a and 5a were unambiguously confirmed by single-crystal X-ray analysis; for selected data see Figures 1 and 2. Scheme 1. Spiropentane (I), Phospha-Spiropentane Derivatives IIÀIV, and Phospha-S...