Organische Phosphorverbindungen XXXVII. Darstellung und Eigenschaften von Bis-(dialkoxyphosphonyl-methyl)-, Bis-(alkoxyphosphinyl-methyl)-und Bis-(oxophosphoranyl-methyl)-phosphinsäureestern sowie der entsprechenden Säuren [1]

Bis-chloromethyl-alkyl-and - aryl-phosphine oxides, (CICH₂₎₂P(O)R, which are obtained by reaction of (CICH₂₎₂P(O)Cl with GRIGNARD reagents, undergo a MICHAELIS -ARBUSOV reaction when heated for several hours with trivalent phosphorus esters (phosphites, phosphonites, or phosphinites) at 170–180°C. The reaction affords bis-(dialkyloxyphosphonyl-methyl)-, bis (alkyloxyphosphinyl-methyl)-, and bis-(oxophosphoranyl-methyl)-, -alkyl- or -aryl-phosphine oxides, R(O)P[CH₂P(O)R′R″]₂ R = CH₃, C₂H₅, n-C₈H₁₇, n-C₁₂H₂₅, C₆H₅; R′ and R″ = C₂H₅O, C₄H₉O, C₆H₅, CH₃ in good yields. Conversion of the compounds containing alkyloxy groups to the free acids is achieved by refluxing with conc. HCl. Bis-(dihydroxyphosphonyl-methyl)-dodecylphosphine oxide, n-C₁₂H₂₅(O)P[CH₂P(O) (OH)_2]2, obtained by hydrolysis of the all-ethyl ester, titrates in aqueous solution as a tetrabasic acid with breaks at pH = 4 (two equivalents), pH = 6,9 (one equivalent) and pH = 9,6 (one equivalent). This acid, its disodium salt (m. p. 405–410°) and its tetrasodium salt (m.p. > 460°) are surface active and are excellent chelating agents. The ¹H- and ³¹P-NMR. spectra of all the compounds prepared are discussed.     

Bis(trimethylsilyl)-hypophosphit und Alkoxycarbonylphosphonigsäure-bis(trimethylsilyl)ester als Schlüsselsubstanzen für die Synthese von Organophosphorverbindungen

Bis(trimethylsilyl)hypophosphite und Alkoxycarbonylphosphonous Acid Bis(trimethylsilyl) esters as Building Blocks in Organophosphorus Chemistry The oxidation of pure bis(trimethylsilyl)hypophosphite ( BTH ) with chalcogenides forming (Me₃SiO)₂P(X)H (X = O, S, Se, Te) is described as well as its reactions with alkylhalides RX (X = Cl, Br, I) and Cl? C(O)OR (R = Me, Et, Bzl). By reaction with oxygen, sulfur, and selenium the alkoxycarbonylphosphonous acid bis(trimethylsilyl)esters form RO? C(O)? P(X)(OSiMe₃)₂ (X = O, S, Se) whereas with Cl? C(O)OR the bis(alkoxycarbonyl)-phosphinic acid trimethylsilylesters are obtained. After partial hydrolysis the resulting instable RO? C(O)? P(O)H(OSiMe₃) gives RO? C(O)? P(O)(OSiMe₃)? CH₂? NH? A? COOR′ (A = CH₂, CH₂CH₂, CHCH₃, CH₂CH₂SH, CHCH(CH₃)₂,…) when allowed to react with hexahydro-s-triazines of the aminoacid esters. Reactions of the alkoxycarbonyl-P-silylesters with NaOR or NaOH result in the corresponding mono-, di-, or trisodium salts. With mineral acids decarboxylation occurs, but H? P(O)(OH)? CH₂? NH? A? COOH can be obtained, too. The structure of the compounds described are discussed by their n.m.r. data.     

Synthese von N-Di(alk-, ar-)oxyphosphoryl-tri(alk-, ar-)-oxyphosphazenen, (RO)2P(O)?NP(OR)3, durch P?N-Bindungsknüpfung

Synthesis of N-Di(alk-, ar-)oxyphosphoryl-tri(alk-, ar-)oxyphosphazenes, (RO)₂P(O)? N?P(OR)₃, by P? N-Bond Formation The title compounds can be prepared from di- and triesters of phosphorous acid, sodium azide, and carbon tetrachloride in a single step procedure and in high yields. Due to the combination of the Atherton-Todd and the Staudinger reaction toxic phosphoric acid ester azides are formed only in situ and their concentration is kept very small. As by-products trichloromethane phosphonic acid esters, (RO)₂P(O)CCl₃, esters of phosphoric acid and condensed phosphoric acids as well as N-alkylimidodiphosphoric acid esters, [(RO)₂P(O)]₂NR, are formed. Their formation can be avoided or reduced by choosing suitable reaction conditions. The mechanism of the reaction is discussed.     

Organische Phosphorverbindungen 44 Darstellung und Eigenschaften von Bis-(ß-chloräthyl)-phosphinsäure-Derivaten [1]

Reaction of ClCH₂CH₂PCl₂ with ethylene oxide gives the phosphonous acid ester ClCH₂CH₂P (OCH₂CH₂Cl)₂ which on heating to 120° rearranges to the phosphinic acid ester (ClCH₂CH₂)₂P(O)OCH₂CH₂Cl ( 3 ). Chlorination of 3 with PCl₅ in CCl₄-solution yields the phosphinic chloride (ClCH₂CH₂)P(O)Cl ( 4 ), which on treatment with P₂S₅ at 170° produces the thioderivative, (ClCH₂CH₂)₂P(S)Cl, (₅). Treatment of 4 and 5 with alcohols, mercaptanes, or amines in the presence of an acid binding agent leads to the corresponding phosphinic and thiophosphinic acid derivatives, (ClCH₂CH₂) P (X)Y, (X = O, S; Y = OR, SR, NR₂) ( 6 ). Reaction of 6 with excess base yields the corresponding divinylphosphinic and divinylthiophosphinic acid derivatives (CH₂ = CH)₂P (X) Y (X = O, S; Y = OR, SR, NR₂) ( 7 ). Bis-(ß-chloroethyl)-phosphinates, e. g. (ClCH₂CH₂)₂P (O) OEt, undergo a Michaelis-Arbuzov reaction when heated with phosphites to 160–170° to give bis-(phosphonylethyl)-phosphinates, e.g. (EtO) (O)P[CH₂CH₂CH₂P(O)(OEt)₂]₂ ( 8 ), which on hydrolysis with conc. HCl under reflux yield the corresponding acid HO₂P(CH₂CH₂PO₃H₂)₂.     

Die Reaktion der Zweikomponentensysteme P(OR)3 − x(NR2)x (x = 0–3)/CCl4 und P4/CCl4 mit HF-Donatoren

Reaction of the Two-component Systems P(OR)_{3 ? x}(NR₂)_x (x = 0–3)/CCl₄ and P₄/CCl₄ with HF-Donators The combination of organylammonium fluorides and carbon tetrachloride is a good agent for oxidative fluorination of trivalent phosphorus compounds. As oxidation products [(RO)PF₅]^? and (RO)₂P(O)F are obtained from P(OR)₃, (Et₂N)₂P(O)F and (Et₂N)₂(EtO)PF₂ from P(OEt)(NEt₂)₂ as well as (Et₂N)₃PF₂ and [(Et₂N)₃PF]⁺ from P(NEt₂)₃. In the system R₂NH/CCl₄/Et₃N · n HF P₄ is fast oxidized forming [HPF₅]^?, R₂NH · PF₅ and (R₂N)₂P(O)F. In the case of simultaneous addition of alcohols [(RO)PF₅]^?, (RO)₃PO and (R₂N)₂P(O)F are formed. The reactions are controlled by the nucleophilic power and the concentration of fluoride, the acidity of the system, and the temperature.     

Organische Phosphorverbindungen XXXVIII. Darstellung und Eigenschaften von Tris-(dialkoxyphosphonyl-methyl)-, Tris-(alkoxyphosphinyl-methyl)-und Tris-(oxophosphoranyl-methyl)-phosphinsäureestern sowie der entsprechenden Säuren [1]

Tris-chloromethyl-phosphine oxide, (ClCH₂₎₃ P?O(I), is obtained by chlorination of (HOCH₂₎₃P?O with PCl₅ or (C₆H₅₎₃PCl₂, and also by oxidation of (CICH₂₎₃P?O and (ClCh₂₎₂(CH₃)P?O. High yields of tris-(dialkyloxyphosphonly-methyl)-phosphine oxides, [RO₂(O)PCH_2]2P?O (II) (R?CH₃, C₂H₅, iso-C₃H₇, n-C₄H₉, 2- ethyl-hexyl), tris (alkyloxyphosphinyl-methyl)-phosphine oxides, [R₂(O)PCH_2]3P?O(R = C₆H₅, CH₃) are obtained by heating tris-chloromethyl-phosphine oxides, [(RO) (R′) (O)PCH_2]3P?O (R = C₄H₉, R′? C₆H₅) and tris-(oxophosphoranyl-phosphine oxides with phosphites, phosphonites and phosphinites, respectively, at 170–180°C for several hours. Compounds II possess an extraordinarily high absorption capacity. Thus a warm. 2% solution of II (R = C₂H₅) in benzene solidifies completely on cooling so that no benzene can be poured off. Tris-dihydroxyphosphonyl-methyl)-phosphine oxide, [(HO)₂(O)PCH_2]3P?O, obtained by hydrolysis of II (R ? C₂H₅) with refluxing conc. HCl or by thermal decomposition of II (R ? iso-C₃H₇) at 190°, titrates in aqueous solution as a hexabasic acid with breaks at pH = 4,4 (three equivalents) and pH = 10,7 (three equivalents). It forms crystalline salts with amines, alkali and alkaline earth metals, and is an excellent chelating agent. The ¹H- and ^31?P-NMR. spectra of all the compounds prepared are discussed.     

[1,3]-Carbanionische Umlagerungen – Synthese von Bis-(o-hydroxyphenyl)silicium-Verbindungen

[1.3]-Carbanionic Rearrangements. Synthesis of Bis-(o-hydroxyphenyl) silane Derivatives Bis-(o-halophenoxy)silanes react via metallation in a fast two step [1.3]-carbanionic rearrangement to the sodium salts of the bis-(o-hydroxyphenyl)silanes (R¹R²Si(o-C₆H₄ONa)₂; R¹ = Me, OMe…). These are protolyzed to the free phenols or are giving ethers and esters by reacting with reactive halogen compounds in an one pot reaction.     

1,3,4-Oxa- und 1,3,4-Thia-diphospholane aus Diphosphorsubstituierten 2-Oxa- und 2-Thia-propanen

1,3,4-Oxadiphospholanes and 1,3,4-Thiadiphospholanes from Diphosphorus-substituted 2-Oxa- and 2-Thia-propanes The synthesis of phosphonates and phosphinates of the type (RO)₂(O)PCH₂ZCH₂P(O)(OR)₂, R¹(RO)(O)PCH₂ZCH₂P(O)(OR)₂ and R¹(RO)(O)PCH₂ZCH₂P(O)(OR)R¹ (with Z = O, S; R = Et, Prⁱ; R¹ = Me, Ph) is reported. Acyclic diphosphanes, R¹(H)PCH₂ZCH₂P(H)R² (with Z = O, S; R¹ = R² = H, Me, Ph; R¹ = H, R² = Me), and 1,3,4-Oxadiphospholanes as well as 1,3,4-Thiadiphospholanes are obtained from the esters by reduction.     

Halogenation behaviour of bidentate ligand-bridged derivatives of [Ru3(CO)12] and [Os3(CO)12]

Reaction of the ligand-bridged derivatives [M₃(CO)₁₀{μ-(RO)₂PN(Et)P(OR)₂}] and [M₃(CO)₈{μ-(RO)₂PN(Et)P(OR)₂}₂] (M = Ru or Os; R = Me or Prⁱ) with halogens leads to the formation of cationic products [M₃(μ-X)(CO)₁₀{μ- (RO)₂PN(Et)P(OR)₂}]⁺ and [M₃(μ-X)(CO)₈{μ-(RO)₂PN(Et)P(OR)₂}₂]⁺ (X = Cl, Br or I) in which the halogen bridges an opened edge of the metal atom framework; the crystal structure of [Ru₃(μ-I)(CO)₈{μ-(MeO)₂PN(Et)P(OMe)₂}₂]PF₆ is reported.     

Metallkomplexe mit biologisch wichtigen Liganden. CLVII [1] Halbsandwich‐Komplexe mit Isocyanoacetylaminosäureestern und Isocyanoacetyldi‐ und tripeptidestern („Isocyano‐Peptide”︁)

Metal Complexes of Biologically Important Ligands, CLVII [1] Halfsandwich Complexes of Isocyanoacetylamino acid esters and of Isocyanoacetyldi‐ and tripeptide esters (?Isocyanopeptides”?) N‐Isocyanoacetyl‐amino acid esters CNCH₂C(O) NHCH(R)CO₂CH₃ (R = CH₃, CH(CH₃)₂, CH₂CH(CH₃)₂, CH₂C₆H₅) and N‐isocyanoacetyl‐di‐ and tripeptide esters CNCH₂C(O)NHCH(R¹)C(O)NHCH(R²)CO₂C₂H₅ and CNCH₂C(O)NHCH(R¹)C(O)NHCH (R²)C(O)NHCH(R³)CO₂CH₃ (R¹ = R² = R³ = CH₂C₆H₅, R² = H, CH₂C₆H₅) are available by condensation of potassium isocyanoacetate with amino acid esters or peptide esters. These isocyanides form with chloro‐bridged complexes [(arene)M(Cl)(μ‐Cl)]₂ (arene = Cp*, p‐cymene, M = Ir, Rh, Ru) in the presence of Ag[BF₄] or Ag[CF₃SO₃] the cationic halfsandwich complexes [(arene)M(isocyanide)₃]⁺X^? (X = BF₄, CF₃SO₃).     

Metallabis(phosphonate) als Chelatliganden. II. Synthese und Reaktivität ein- und zweikerniger Palladiumbis(phosphonat)-Komplexe mit OHO- und OBF2O-Brückenbindungen

Metallabisphosphonates as Chelating Ligands. II. Synthesis and Reactivity of Mono- and Binuclear Palladiumbisphosphonate Complexes Containing OHO and OBF₂O Bridges The complexes C₅H₅Pd[{P(OR)₂O}₂H] ( 1 : R = Me; 2 : R = Et) are formed either by reaction of C₅H₅Pd(2-MeC₃H₄) with dimethyl- and diethylphosphite or by reaction of [ClPd{P(OR)₂O}₂H]₂ ( 3 : R = Me; 4 : R = Et) with TlC₅H₅. With excess HP(O)(OMe)₂, the π-allyl complex (2-MeC₃H₄)Pd[{P(OMe)₂O}₂H] ( 5 ) is also formed (besides 1 ) from C₅H₅Pd(2-MeC₃H₄). The ¹H and ³¹P n.m.r. spectra indicate that in 1 – 5 the PdP₂O₂H chelate ring presumably contains a symmetrical OHO-hydrogen bond. The reaction of 3 with BF₃ etherate leads to the binuclear complex [ClPd{P(OMe)₂O}₂BF₂]₂ ( 6 ) which reacts with TlC₅H₅ to yield C₅H₅Pd[{P(OMe)₂O}₂BF₂] ( 7 ). From C₅H₅Pd[{P(OR)₂O}₂H] ( 1 , 2 ) and NH₃ the bisamminepalladium bisphosphonates(NH₃)₂Pd[P(OR)₂O]₂ ( 8 , 9 ) are formed which probably possess a trans-configuration. The reaction of 8 , 9 with CF₃COOH does not lead to a corresponding Pd[{P(OR)₂O}₂H] chelate complex but instead gives by elimination of NH₃ polymeric palladium bisphosphonates [Pd{P(OR)₂O}₂]_n ( 10 , 11 ). 1 reacts with thallium acetylacetonate to give C₅H₅Pd[P(OMe)₂O]₂Tl ( 12 ).     

Über die Struktur von Bis-(dihydroxoboroxalendiamiddioximato)-nickel(II)-tetrahydrat

The space group of the sparingly soluble brown coloured bis-(dihydroxobor-oxalene-diamide-dioximato)-nickel(II)-tetrahydrate (C₄H₁₂N₈O₈B₂Ni · 4 H₂O) is P21/c with a = 9.25, b = 13.27, c = 6.61 Å and β = 92.7°. The structure was solved on single crystals. There are two molecules in the unit cell. Within the square planar complex the nickel atom is bonded to the four nitrogen atoms of the plane system of the two dioximato ligands (Ni? N = 1.84 ± 0.02 Å). Each of the boron atoms is tetrahedrally surrounded by two oxygen atoms belonging to the oxime groups and two hydroxyl groups (B? O = 1.50 ± 0.06 Å). Thus the complex has the conformation of a chair form. The water molecules participate in intermolecular hydrogen bonds. There is no interaction between Ni atoms.     

Bildung und NMR-spektroskopische Charakterisierung von Alk-(ar-)oxyderivaten von Trichlorphosphazen-N-phosphoryldichlorid,Cl3PN?P(O)Cl2, Imido- und N-Methylimidodiphosphoryltetrachlord,Cl2P(O)NHP(O)Cl2 bzw. Cl2P(O)N(CH3)P(O)Cl2

Formation and N.M.R.-Spectroscopic Characterization of Alk-(ar-)oxy Derivatives of Trichlorophosphazene-N-phosphoryldichloride, Cl₃P?N? P(O)Cl₂, Imido- and N-Methylimidodiphosphoryltetrachloride, Cl₂P(O)NHP(O)Cl₂ and Cl₂P(O)N(CH₃)P(O)Cl₂ The ester chlorides and esters P₂NOCl_5?x(OR)_x (x = 1?5), P₂(NH)O₂Cl_4?x(OR)_x (x = 1–4) and P₂(NCH₃)O₂Cl_4–x(OR)_x (x = 1–4) derived from the title compounds by substitution of chlorine atoms by alk- or aroxy groups are characterized by their ³¹P-n.m.r. data. The possibilities for forming these compounds by alcoholysis, chloridolysis, dealkylation and P? N-bond formation are discussed.     

μ-Oxo-bis[trimethylantion(V)] – Derivate von Dithiocarbamin-, Xanthogen-und Dithiophorsäuren

μ-Oxy-bis[trimethylantiomony(V)] Derivatives of Dithiocarbaminic-, Xanthogenic-, and Dithiophoric Acids u-Oxy-bis[trimethylantimony(V)] derivatives of the type [Me₃SbL]₂O (L = S₂CNR₂, S₂COR, S₂P(OR)₂) are obtained by the reaction of [Me₃SbBr]₂O with sodium dithiocarbamtes, xanthogentates and dithiophosphates. The products are characterized by elementary analysis molecular weight determination, IR, ¹H-NMR, and ¹³C-NMR spectroscopy.     

Zur Umsetzung des Zweikomponentensystems Trialkylphosphit/ Tetrachlorkohlenstoff mit wasserstoffhaltigen Nucleophilen 2. Die Reaktion mit Ammoniak und Aminen

Reaction of the Two-component System Trialkylphosphite/Carbon Tetrachloride with Nucleophiles Containing Hydrogen. 2. Reaction with Ammonia and Amines Ammonia and primary amines react with the two-component system trialkylphosphite/carbon tetrachloride yielding diester-amides of phosphoric acid, (RO)₂P(O)NHR′. If an excess of amine is used compounds of the type ROP(O)(NHR′)₂ and OP(NHR′)₃ are formed too. By the reaction of (RO)₃P/CCl₄ in presence of secondary and tertiary amines the first reaction product is (RO)₂P(O)CCl₃ which yields with the amine [NRR′R″R″′]⁺[Cl₃CP(OR)O₂]^?; (R = Et, Bu).     

Oligomere μ-Imidophosphorsäurechloride und -amide

Oligomeric μ-Imidophosphoric Acid Chlorides and Amides Oligomeric μ-imidophosphoric acid chlorides. Cl₂(O)P? [NH? P(O)Cl]_n? Cl, (n = 1, 2, 3) are obtained by solvolysis of the linear phosphorylchlorphosphazenes, Cl₂(O)P? [N?PCl₂]_n? Cl, with the stoichiometric amount of anhydrous formic acid. The chlorides react with ammonia forming the amides. The amides are characterized by paper and gel chromatography. Course and rate of hydrolysis of diimidotriphosphoric acid pentaamide depend on pH.     

Unexpected Reaction of Fe3(CO)12 with Dialkyldithiophosphate: The Case of P–S Bond Activation

The reaction of Fe₃(CO)₁₂ with O,O′‐dialkyldithiophosphate diethylamine salts (RO)₂P{S}SH · Et₂NH (R = CH₃, CH₂CH₃) resulted in the formation of trinuclear cluster complex {μ‐SP(OR)₂Fe[S₂P(OR)₂)]S‐μ]}Fe₂(CO)₆ [R = CH₃ ( 1 ), CH₂CH₃ ( 2 )]. The two complexes were characterized by elemental analysis, FT‐IR, NMR (¹H, ³¹P and ¹³C) spectroscopy, as well as by X‐ray diffraction analyses. Crystal structures reveal that one P–S bond is cleaved during the reaction, yielding the [2Fe2S] unit together with FePS₃(CO)₂. The other dialkyldithiophosphate coordinated with iron by S, S chelating model. The trinuclear cluster was observed with the P‐Fe and S–Fe bond formed by the P‐S activation. In addition, the electrochemical properties for complex 2 as an illustration was also studied by cyclic voltammetry in MeCN.     

Contributions on thermal behaviour and crystal chemistry of anhydrous phosphates. XIX. Tri-chromium(II)-bis-phosphate Cr3(PO4)2 (≙ Cr6(PO4)4) – A transition metal(II)-orthophosphate with new structure type

Deep blue-violet single crystals of hitherto unknown chromous orthophosphate have been obtained reducing CrPO₄ by elemental Cr at temperatures above 1050°C in evacuated silica ampoules (NH₄I or I₂ as mineraliser). The complex structure of Cr₃(PO₄)₂ (P2₁2₁2₁, Z = 8, a = 8.4849(10) Å, b = 10.3317(10) Å, c = 14.206(2) Å) contains six crystallographically independent Cr²⁺ per unit cell. Five of them are coordinated by four oxygen atoms which form a distorted (roof shaped) square plane as first coordination sphere at interatomic distances 1.96 Å ? d(Cr? O) ? 2.15 Å. Their coordination is completed by additional oxygen atoms (2 or 3) at distances 2.32 Å ? d(Cr? O) ? 3.21 Å. The sixth Cr²⁺ shows six-fold octahedral coordination with strong radial distortion (d(Cr? O): 1.97, 2.04, 2.15, 2.28, 2.29, 2.53 Å). The four different [PO₄] groups exhibit only minor deviations from ideal tetrahedral geometry (1.51 Å ? d(P? O) ? 1.57 Å, 104.3° ? ∠(O? P? O) ? 114.4°). An unusually low magnetic moment μ_exp = 4.28(2) μ_B (θ_P = ?54.8(5) K) has been observed for Cr²⁺.     

Darstellung und Bildungsmechanismus von π-Cyclopentadienyl-nickel-(tert.-phosphit)-dialkylphosphonat-Komplexen – eine metallorganische Variante der Michaelis-Arbuzov-Reaktion

Synthetic routes for complexes of the type π-C₅H₅Ni[P(OR)₃]X have been developed. Nickelocene reacts with tertiary phosphites P(OR)₃ in the presence of CX₄ to give the complexes for which R = Me, Ph; X = Cl, and R = Ph; X = Br. π-C₅H₅Ni(CO)I reacts with P(OR)₃ to give the complexes for which R = Me, Et, Ph. [π-C₅H₅Ni(P(OMe)₃)₂]Cl is also formed in the preparation of π-C₅H₅Ni[P(OMe)₃]Cl from nickelocene; the corresponding [π-C₅H₅Ni(P(OEt)₃)₂]I is obtained from π-C₅H₅Ni[P(OEt)₃]I and P(OEt)₃. π-C₅H₅Ni[P(OMe)₃]X (X = Cl, I) react with P(OMe)₃ to give π-C₃H₅Ni[P(OMe)₃] [P(O)(OMe)₂] in quantitative yields, but with P(OEt)₃ and P(OPh)₃ π-C₅H₅Ni[P(OEt)₃] [P(O)(OMe)₂] respectively π-C₅H₅Ni[P(OPh)₃] [P(O)-(OMe)₂] are obtained as the main products. The complex (t-C₄H₉C₅H₄)Ni[P(OMe)₃] [P(O) (OMe)₂] can be synthesized by the same route. The course of the reactions of π-C₅H₅Ni[P(OR)₃]X and P(OR′)₃ has been investigated in some detail. Intermediate compounds {C₅H₅Ni[P(OR)₃] [P(OR′)₃]X} with a π-bonded cyclo- pentadienyl ligand have been detected at low temperatures by ¹H- and ¹³C-NMR.-spectroscopy. They are stable up to about ?10° and react at higher temperatures smoothly to π-C₅H₅Ni[P(OR)₃] [P(O) (OR′)₃] and R′X. The structure proposed for the intermediates suggests that the mechanism of formation of the nickel phosphonate complexes is quite similar to that of the Michaelis-Arbuzov reaction.     

Stabilisation of [Fe2(CO)9] and [Ru2(CO)9] bu substitution with bridging diphosphorus ligands

Reaction of [Fe₂(CO)₉] with a half molar amount of R₂PYPR₂ (Y = CH₂, R = Ph, Me, OMe or OPrⁱ; Y = N(Et), R = OPh, OMe or OCH₂; Y = N(Me), R = OPrⁱ or OEt) leads to the ready formation of a product which on irradiation with ultraviolet light rapidly decarbonylates to the heptacarbonyl derivative [Fe₂(μ-CO)(CO)₆{μ-R₂PYPR₂}]. Treatment of the latter with a slight excess of the appropriate ligand results, under photochemical conditions, in the formation of the dinuclear pentacarbonyl complex [Fe₂(μ-CO)(C))₄{μ-R₂PYPR₂}₂] but under thermal conditions in the formation of the mononuclear species [Fe(CO)₃{R₂PYPR₂}]. Reaction of [Ru₃(CO)₁₂] with an equimolar amount of (RO)₂PN(R′)P(OR)₂ (R′ = Me, R = Prⁱ or Et; R′ = Et, R = Ph or Me) under either thermal or photochemical conditions produces [Ru₃(CO)₁₀{μ-(RO)₂PN(OR)₂}] which reacts further with excess (RO)₂PN(R′)P(OR)₂ on irradiation with ultraviolet light to afford the dinuclear compound [Ru₂(μ-CO)(CO₄{μ-(RO)₂PN(R′)P(OR)₂}₂]. The molecular structure of [Ru₂(μ-CO)(CO)₄{μ-(MeO)₂PN(Et)P(OMe)₂}₂], which has been determined by X-ray crystallography, is described.