The redox behaviour of di-, tri-, penta- and hexaphospha ferrocene complexes and of five transition metal carbonyl complexes of the triphospha ferrocene [Fe(η5-C2tBu2P3-(η5-C5Me5)] 2 has been investigated by cyclic voltammetry. The oxidation potential of the phospha ferrocene complexes is determined by the number of electron-donating alkyl groups and phosphorus atoms, the latter showing electron-withdrawing properties. Electrochemical investigations on metal carbonyl complexes of 2 revealed an anodic shift of the oxidation potential of 2. The data allow conclusions to be drawn about the overall σ-donor-π-acceptor properties of 2.

Synthesis and structural studies of the iron “sandwich” complex [Fe(η5-C5Me5(η-C3tBu3P2)] 1 are described. The lone pair electrons of the two adjacent phosphorus atoms of the C2tBu2P3 ring in the triphospha-ferrocene complex [Fe(η5-C5Me5)(η5-C2tBu2P3)] 2 can ligate to other metal centres. The results of single crystal X-ray structural studies of the molybdenum and tungsten pentacarbonyl η1-complexes [Fe(η5-C5Me5)(η5-C2tBu2P3)M(CO)5] (4: M = Mo, 5: M = W) are discussed; they form an isostructural series with the previously reported chromium complex. The starting material 2 reacts with [(C5H4Me)(CO)2Mn(THF)] to form the adduct [Fe(η5-C5Me5)(η5-C2tBu2P3)Mn(CO)2(η5-C5HH4Me)] 6. The phenyl-substituted di- and triphosphacyclopentadienides [Na(DME)3][C3Ph3P2] and [Na(DME)3][C2Ph2P3] (DME = 1,2-dimethoxyethane) react with ferrous chloride and Li[C5Me5] to give the ‘sandwich’ compounds [Fe(η5-C5Me5)(η5-C3Ph3P2)] 9 and [Fe(η5-C5-C5Me5(η5-C2Ph2P3)] 10. The The latter reacts with W(CO)5(THF) to yield the η1-complex [Fe(η5-C5Me5)(η5-C2Ph2P3)W(CO)5] 11.

Reaction of (t)Bu-C=P with [Ru-3(CO)(12)] or [Os-3(CO)(12)] afforded the novel phosphinidene complexes [Ru-3(CO)(9){PC(CO)(t)Bu}(2)] 1 or [Os-3(CO)(9){PC(CO)(t)Bu}(2)] 2, respectively. A crystal structure analysis re vealed a nido structure for both complexes in agreement with a contribution of four electrons to the cluster framework by each phosphinidene ligand. A minor product of the reaction with [Os-3(CO)(12)] is the complex [Os-3(CO)(9){P(C(CO)(t)Bu)C((t)Bu)P(Os-3(CO)(11))}] 3, consisting of two triosmium units Linked by a P-C-P framework resulting from coupling of phosphinidene and phospha-alkyne fragments. Complex 3 was also characterized by means of a crystal structure analysis.

Syntheses and structures of penta- and hexaphosphorus analogues of ferrocene have been described recently1. Unlike their simple ferrocene analogues, these complexes have further ligating potential towards other transition metal centres by virtue of the availability of the ring phosphorus lone-pair electrons that are not involved in the η5-coordination. We now describe the first examples of coordination compounds of the triphospha-ferrocene [Fe(η5-C5Me5) (η5-C2 tBu2P3]. In the ruthenium complex [Fe(η5-C5Me5)(η5-C2 tBu2P3) Ru3(CO)9] 2 two adjacent phosphorus atoms of the η5-C2 tBu2P3 ring are interlinked by a ruthenium carbonyl cluster in which all three ruthenium atoms interact with the phosphorus atoms. The tetrametallic nickel complex [Fe(η5-C5Me5)(η5-C2 tBu2P3)Ni(CO)2]2 3 represents the first example of intermolecular interlinkage of two phospha-ferrocene systems by two metal centres.

The dimethylamino-substituted phosphaalkene 1 reacts with hexafluoroacetone (HFA) with addition at the P=C bond to form the 1,5,2-dioxaphosphorinane 2. The structure of 2 was confirmed by an X-ray crystal structure analysis. The six-membered ring displays an envelope conformation with the phosphorus atom out of the plane, but the phosphorus is disordered over two sites. Reaction of P-trimethylsilyl-substituted phosphaalkenes with HFA proceeds with retention of the P=C double bond and insertion of HFA into the P-Si bond. Two isomeric products are obtained and are characterized by H-1-, C-13-, F-19-, and P-31-NMR spectroscopy, IR spectroscopy, mass spectrometry, and elemental analysis.

The reaction of N,N′‐dimethyl‐N,N′‐bis(trimethylsilyl)urea (1) or N‐methyl‐N′‐phenyl‐N,N′‐bis(trimethylsilyl)urea (2) with p‐toluenesulfenyl chloride furnished N,N′‐dimethyl‐N‐(p‐tolylthio)‐N′‐

The reactions of 1,3,5-trimethylbiuret with dicyclohexylaminodichlorophosphine and with pyrrolidinodichlorophosphine furnished the triazaphosphinane-diones 1 and 2. Oxidation reactions of the 2-diorganoam ino-1,3,5-triorgano-1,3,5-triaza-2 λ3-phosphinane-4,6-diones 1, 2, and 4-9, as well as 2-fluoro-1,3,5-trimethyl-1,3,5-triaza-2λ3-phosphinane-4,6-dione 10 with hydrogen peroxide, elemental sulphur, phenyl azide, 1-adamantyl azide,p-nitrobenzoyl azide, tetrachloro-orthobenzoquinone, tetrabromo-orthobenzoquinone, 3,5-di-t-butyl-orthobenzoquinone, and hexafluoroacetone led to the respective oxidation products, 12-32, involving either λ4P or λ5P. In the reaction o f the P(III)C1 derivative 11 with 3-m ethyl-l,5-diphenyl-l,5- bis(trimethylsilyl)biuret the bifunctional compound 33 was produced. The new com pounds 1,2 and 12-33 were characterized via their 1H, 13C and 31P and, where appropriate, 19F NMR spectra. In the case o f the four compounds, 3 (previously described in the literature [2]), 13, 31, and 33, single crystal X-ray diffraction studies were conducted. Unusually for this type of heterocycle 3 displays a 1,4-diplanar ring conformation because o f the bulky aromatic substituents. 13 shows an envelope conformation. The hydrogen peroxide solvent molecule has crystallographic inversion symmetry, but may be disordered. In 31 the coordination geometry at phosphorus is trigonal bipyramidal. The five-membered ring shows a twist conform ation associated with the bulky trifluoromethyl groups. The exocyclic P-N bonds in 33 are unusually long.

The lone-pair electrons of one or two directly bonded phosphorus atoms of the C2tBu2P3 ring in the triphospha-ferrocene complex [Fe(η5-C5Me5)(η5-C2tBu2P3)] can coordinate to one or three ruthenium atoms to afford the novel triruthenium carbonyl cluster complexes [Fe(η5-C5Me5)(η5-C2tBu2P3)Ru3(CO)11] and [Fe(η5-C5Me5)(η5-C2tBu2P3)Ru3(CO)9], respectively. The structures of the triruthenium carbonyl cluster fragments were determined by single crystal X-ray diffraction studies.

The cyclic zwitterionic lambda(6)P,lambda(4)P-diphosphorus compound F5P-N(MeP+ [N(Me)C(=O)](2)NMe (3), which contains a biuret system, was synthesized by the reaction of (MeNPF(3))(2) (1) with MeNCO (2). Compound 3 was characterized by means of H-1-, C-13-, F-19- and P-31-NMR spectroscopy, IR spectroscopy, and mass spectrometry. A single-crystal X-ray structure determination revealed the presence of two independent formula units, in which the -N(Me)PF5 side chains display widely differing conformations.

Synthesis and X‐Ray Crystal Structure Analysis of a Novel Mixed‐Valent Zwitterionic Diphosphorus Fluoro CompoundThe cyclic zwitterionic λ6P,λ4P‐diphosphorus compound F5P–N(Me)P+ [N(Me)C(=O)]2NMe (3), which contains a biuret system, was synthesized by the reaction of (MeNPF3)2 (1) with MeNCO (2). Compound 3 was characterized by means of 1H‐, 13C‐, 19F‐ and 31P‐NMR spectroscopy, IR spectroscopy, and mass spectrometry. A single‐crystal X‐ray structure determination revealed the presence of two independent formula units, in which the –N(Me)PF5 side chains display widely differing conformations.

The lone pair electrons of the two adjacent phosphorus atoms of the C2But2P3 ring in the triphospha0-ferrocene complex [Fe(η5-C5Me5)(η5-C2But2P3)] can ligate to other metal centres to afford novel bi- and tetrametallic complexes, whose structures have been elucidated by NMR and single-crystal X-ray studies. In the reaction of [Fe(η5-C5Me5)(η5-C2But2P3)] with Ni(CO)4 the tetrametallic complex [Fe(η5-C5Me5)(C2But2P3)Ni(CO)2]2 is formed. This complex is of particular interest because it represents the first example of the intermolecular interlinkage of two phospha-ferrocene units by two metal centres. A six-membered ring consisting of four phosphorus and two nickel atoms forms the core of the molecule and exhibits a boat configuration. The starting material [Fe(η5-C5Me5)(η5-C2But2P3)] reacts with Cr(CO)5(thf), W(CO)5(thf) and Fe2(CO)9 to yield the η5-complexes [Fe(η5-C5Me5)(η5-C2But2P3)M(CO)n] (M = Cr, W, n = 5; M = Fe, n = 4). Variable-temperature η31P{1H} NMR studies reveal that these complexes are fluxional in solution.

Acylphosphines of the type (1-Ad)nP[C(:O)R]3-n (n = 1,2; R = (t)Bu, 1-Ad, Ph) were synthesized via the reaction of 1-AdPH2 or (1-Ad)2PH with the corresponding carboxylic acid chlorides/NEt3. Tle reaction of 1-AdPH, with phtaloyl dichloride/NEt3 led to the five-membered heterocycle 4. In the case of n = 1, R = 1-Ad the monosubstitution product 1-AdP(H)C(:O)(1-Ad) lb was also observed. 1-AdP(H)C(:O)Ph le was selectively formed when 1-AdPH, was allowed to react with PhC(:O)Cl/K2CO3, whereas the remaining PH-proton in le could be substituted by C(:O)(t)Bu in its reaction with (t)BuC(:O)CI/NEt3 to give 2d. The action of trifluoroacetic acid anhydride on 1-AdPH2 or (1-Ad)2PH led to the trifluoroacetyl phosphines 2c and 3c. The reaction of I-AdP[C(:O)(t)Bu]2 2a with aqueous H2O2 or elemental sulfur furnished the corresponding chalcogenides 5 and 6, with a large excess of methyl iodide [1-AdPMe3]I 7 was formed. The carbonyl complexes (L)M(CO)n (L = 2a; M = Ni, n = 3: 8; M = Fe, n = 4: 9) were obtained upon reaction of 2a with Ni(CO), and Fe2(CO)9, respectively. Tris-1-adamantoylphosphine 10 was formed as a by-product in the reaction of P(SiMel)3 with 1-AdC(:O)Cl and was converted to the chalcogenides [(1-AdC(:O)]3P(:X) (X = 0: 13; X = S: 14).

In the reaction of phenylisocyanate, 1, with 1,3-dimethylurea, 2, and 1,3-diphenylurea, 4, 1,3-dimethyl-5-phenyl biuret, 3, and 1,3,5-triphenylbiuret, 5, respectively, were obtained. The reaction of 3, 5 and of 1,3,5-trimethylbiuret 6 with a range of P(III) chloro compounds has furnished the new 4,6-dioxo-1,3,5,2 λ3-triazaphosphinanes, 7-16. The characterization of 7-16 rests, especially, on their 1H, 13C and 31P NMR, and mass spectra.