Search

New diphosphinite ligands based on atropoisomeric diol backbones and (R,R)-2,5-dimethylphospholane moieties have been prepared and fully characterised. For each ligand structure, both diastereomers have been synthesised. These ligands are available through a straightforward procedure in good yields. The solid state structures of two diastereomeric ligands are reported. These ligands have been applied to Rh-catalysed asymmetric hydrogenations and hydroformylations of C C bonds as well as in Ir-catalysed asymmetric hydrogenations of C N bonds. Turnover frequencies in the range of 10,000 h−1 and enantioselectivities of up to 98% ee have been achieved. The different chirality elements within the ligands led to marked cooperative effect in catalysis. Interestingly, there is no general privileged diastereomeric structure but rather a matched diastereomer for each application.

An improved synthesis of (R,R)- and (S,S)-hexane-2,5-diol is presented. The (S,S)-derivative was converted into a cyclic sulfate, which on treatment with NaPH2 in liquid ammonia ultimately gave the secondary (R,R)-2,5-dimethylphospholane. This phospholane can be introduced into the side chain of chiral tricarbonylchromium and ferrocene derivatives to give new bidentate ligands of the Josiphos and Daniphos type. Both the ferrocene- and tricarbonylchromium-based diphosphanes have been characterized by X-ray diffraction analysis. A discussion of their structural features is included. The new ligands were successfully applied to the enantioselective hydrogenation of itaconic acid esters. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Novel P,N chelating ligands with three stereogenic centres in positions α to the donor atoms have been prepared in good yields and high enantiomeric purity by a series of reactions beginning with either (R)- or (S)-1-phenylethylamine. These isomers were first lithiated with tBuLi and converted into aminophosphanes 3a by treatment with (Et2N)2PCl. They were transformed into the enantiomeric primary phosphanes 4 by quantitative solvolysis with ethanol to give the phosphonous acid esters 3b and subsequent reduction with LiAlH4. Stepwise treatment of 4 with nBuLi and the cyclic sulfate of (S,S)-2,5-hexanediol gave the isomeric tertiary phosphanes (R,RR)-5 and (S,RR)-5. Treatment of the aminophosphane (R)-3a with (R)-2,2′-binaphthol yielded the aminophosphonite (R,R)-6 in high yields. Cationic (COD)Rh complexes of 5 were prepared by treatment with [Rh(COD)Cl]2, the PF6− salts 7a being isolated. Analogous (2,5-norbornadiene)Rh complexes 7b were prepared similarly. The chelate nature of the P,N ligands in these salts is indicated by their NMR spectra in solution and is confirmed by the crystal structures of (R,RR)-7a and (S,RR)-7a. With the exception of (S,RR)-7a, the complexes 7a and 7b are shown to catalyse the asymmetric hydrogenation of methyl acetamidocinnamate at room temperature. Differences in the catalytic activity of the complexes are related to the different dynamic behaviour detected by the 1H EXSY spectra for the COD ligands of 7a. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Reaction of 2,2'-difluoro-1,1'-biphenyl with chlorosulfonic acid and subsequent hydrolysis followed by neutralization with potassium or sodium hydroxide affords disodium or dipotassium 5,5'-disulfonato-2,2'-difluoro-1,1'-biphenyl (1a, 1b). On treatment of 1b with diphenyl- or phenylphosphine in the superbasic medium DMSO/KOH, phosphine ligand 2 or 3 with a disulfonated 1,1'-biphenyl backbone or a dibenzophosphole moiety is formed. The structure of the oxide of 5-phenyldibenzophosphole 3, which crystallizes as 4.2.5H(2)O in the monoclinic space group P2(1)/n with a = 13.799(3) A, b = 19.246(4) A, c = 17.764(4) A, beta = 105.63(3) degrees, and Z = 4, has been determined by X-ray analysis. Nucleophilic phosphination of 1a with NaPH(2) in liquid ammonia yields the sodium phosphide 5a which on protonation gives the water-soluble 5H-dibenzophosphole 5. Reaction of 1b with PH(3) in the superbasic medium DMSO/KOtBu affords 5b in addition to the oxidation product 6a. On oxidation of 5a or 5b with H(2)O(2), the sodium or potassium salts of the sulfonated phosphinic acids 6a or 6b, respectively, are formed. Alkylation of the sodium dibenzophospholide 5a with 2,2'-bis(chloromethyl)-1,1'-biphenyl or 1,4-di-O-p-toluenesulfonyl-2,3-O-isopropylidene-D-threitol yields the chiral water-soluble bidentate phosphine ligands 8 and 9, respectively.

Phosphine ligands containing mono- and multiply substituted aromatic substituents (1–13, 19a and 19b) are accessible in high yields by palladium-catalyzed PC coupling reactions between primary, secondary or disecondary phosphines and iodo- or bromoaromatic compounds. The reaction is of broad applicability and compatible with electron donor or electron acceptor substituents in ortho, meta or para position to the halogen in the aromatic ring systems. It may be performed in protic and aprotic solvents. The chiral spirocyclic boronato complex 15a is formed upon reaction of 3 with boric acid, while with benzeneboronic acid 15c with a peripheral Lewis acid group is obtained. The Pd-mediated PC coupling reaction of primary phosphines proceeds stepwise, tailor-made chiral secondary (16) and tertiary phosphines (17) being formed in high yields. Through combination with Suzuki-type CC coupling reactions, the scope of Pd-catalyzed PC coupling may be extended further, with novel ligands (20a, 20b, 21a, 21b) with biphenylyl substituents being accessible. The X-ray structures of the salicylic acid derivative 3 (space group P 1 ) and of ortho-iso-propylphenyl-diphenylphosphine 6 (space group Pbca) have been determined.

Base catalyzed addition of 1-vinylimidazole to primary and secondary phosphines affords tertiary phosphines with terminal 1-imidazolyl substituents C3H3N2 in high yields. The X-ray structure of the oxide Ph2P(O)–(CH2)2–1-C3H3N2 has been determined (space group P 1 ). By selective N-protonation and protected group N-quaternization novel cationic phosphines, e.g. 2a, 2b, 9 and 10, with peripheral 1-imidazolium groups are obtained. These are interesting ligands for catalytic reactions in biphasic systems containing ionic liquids as polar phase and may be employed in hydroformylation of long-chain olefins like 1-octene.

Phosphino derivatives of serine R2P–CH2–CH(NHBOC)(COOMe) (2 a–2 d) have been obtained in high yield by nucleophilic phosphination of N-(tert.butoxycarbonyl)-3-iodo-L-alanine methylester with secondary phosphines R2PH (R = Ph, 2-tolyl, 3,5-xylyl, cyclohexyl) in DMF using potassium carbonate as the base. Deprotection of 2 b with HCl affords the amino acid ester hydrochloride [2-Tol2P–CH2–CH(NH3)(COOMe)]+Cl– (3 a). The X-ray structures of 2 a (space group P21/n) and 2 c (space group P 1) have been determined. The two enantiomers of 2 a or 2 c are interconnected by N–H…O hydrogen bridges forming dimers in the solid state. Chirale Phosphinliganden aus Aminosauren. II. Eine einfache Synthese von Phosphinoserinen durch nucleophile Phosphinierungsreaktionen – Rontgenstrukturanalysen von Ar2P–CH2–CH(NHBOC)(COOMe) (Ar = Ph, m-Xylyl) Phosphinoderivate von Serin R2P–CH2–CH(NHBOC)(COOMe) (2 a–2 d) sind in hohen Ausbeuten durch nucleophile Phosphinierung von N-(tert.butoxycarbonyl)-3-iod-L-alaninmethylester mit sekundaren Phosphinen R2PH (R = Ph, 2-Tolyl, 3,5-Xylyl, Cyclohexyl) in DMF unter Verwendung von Kaliumcarbonat als Base auf einfache Weise zuganglich. Die Abspaltung der Schutzgruppe BOC mit HCl in 2 b liefert das Aminosaureesterhydrochlorid [2-Tol2P–CH2–CH(NH3)(COOMe)]+Cl– (3 a). Die Rontgenstrukturanalysen von 2 a (Raumgruppe P21/n) und 2 c (Raumgruppe P 1) wurden durchgefuhrt. Im Festkorper sind die beiden Enantiomeren von 2 a bzw. 2 c durch N–H…O-Wasserstoffbrucken unter Bildung von Dimeren miteinander verknupft.

Reaction of 2-(diphenylphosphino)phenylphosphonous acid tetramethyldiamide 1 with (+)-menthol, (1S,2S,3S,5R)-isopinocampheol and (1R,2R)-trans-cyclohexanediol affords enantiopure phosphino-phosphonite ligands 3–5. The X-ray structures of 1 (space group P21/n) and 3 (space group P21) have been determined. The reaction of 1 with (1R,2R,3S,5R)-(−)-pinanediol proceeds diastereoselectively to afford a novel type of enantiopure phosphino-phosphonite ligand 6 with an asymmetric substituted P atom. On reaction of (+)-cedryl alcohol with 1 the adduct 7 of the phosphonous acid 2-Ph2PC6H4P(O)(H)OH 9 and its dimethylammonium salt is formed through elimination of water and subsequent hydrolysis. The structure of 7 (space group P1) was elucidated by X-ray structural analysis. Reduction of the chlorophosphine 8 with LiAlH4 yields the novel primary–tertiary phosphine 10, which is a valuable starting material for the synthesis of the enantiopure C1 symmetric bidentate phospholane ligands 11 and 12.

The dilithium salt 1a formed by ortho-metallation of N-tert-butoxycarbonylaniline (BOC-aniline) 1 with two equivalents of tert-butyllithium reacts with the chlorophosphines Ph3-nPCln (n = 1 -3) to yield the BOC protected ortho-aminophenylphosphines 2 - 4 in high yields. On deprotection of 2 - 4 with trimethylchlorosilane in the presence of phenol the HCl adducts of the ortho-aminophenylphosphines 5 -7 are formed which may be deprotonated with KOH or NaOH to give the neutral phosphines 5a -7a. The novel secondary phosphine 8 with two ortho-aminophenyl groups is accessible by cleavage of the P-C bond in 7a with metallic lithium and subsequent hydrolysis. The bifunctional P,N ligands 6 or 6a are alternatively accessible by Pd-catalyzed P-C coupling of ortho-iodoaniline with phenylphosphine. If a 1:1 stoichiometry is employed in the coupling reaction of ortho-iodoaniline and phenylphosphine the chiral secondary phosphine 9 is formed.

Mono- and bifunctional guanidinium phosphines (3c, 4a, 4b, 5a–5d, 5f) containing para-and meta-guanidiniumphenyl moieties C6H4 NH C(NH2)(NR2)+ (R=H, Me) are accessible in high yields by Pd catalyzed P C coupling reactions between iodophenyl guanidines I C6H4 NH C(NH)NR2 (meta-, para-isomers; R=H, Me) and phenyl- or diphenylphosphine. The X-ray structure of 3c·MeOH (space group P212121) has been determined, showing a planar guanidinium group in a NH O and NH Cl hydrogen bridged arrangement. Pd(II) and Mo(0) complexes of 5c have been synthesized. The influence of the cationic guanidinium group on the electronic and steric parameters of 5c is discussed. A comparative study of 5c, phosphonated and sulfonated phosphine ligands in the biphasic Pd catalyzed Suzuki-type coupling between m-bromophenyldiphenyl phosphine oxide and para-tolylboronic acid shows 5c to be less active than Ph2P C6H4 4-PO3Na2.

Reaction of (R)-(+)-2,3-epoxy-1-propanol with Ph2PH, configuration in the unit cell. Nucleophilic phosphanylation of (R)-(–)-2,3-O-isopropylideneglycerol tosylate with Ph2PH, Ph(Me)PH, or PhPH2 in the superbasic medium KOH/DMSO affords the novel chiral phosphanes 1a–1c. While 1a is Ph(Me)PH, or PhPH2 yields chiral 3a–3d. Compound 3b was obtained enantiomerically pure. The secondary phosphane obtained enantiomerically pure, 1b and the secondary phosphane 1c are formed as mixtures of diastereoisomers 3c has been employed in syntheses of the hydrophilic tertiary phosphanes 3e, 3f and of the novel bidentate phosphane (RPRC, SPRC) with homochiral β carbon atoms. Derivatization of 1a with phenylboronic acid or 2,2-dimethoxypropane ligands 3g, 3h, all of which have homochiral β carbon atoms. PdII complexes PdL2Cl2 of 1a, 2a, 3a (L) are formed as yields 2a and 3a with 1,3,2-dioxaborolane and 1,3-dioxolane ring systems, respectively. The X-ray structure of 2a (space mixtures of cis/trans isomers. RhI complexes of 1a, 3a, and bidentate 3h have also been synthesized. group P21) reveals the presence of four molecules of R

The nickel(II) complex 3 containing a 14-membered macrocyclic triphosphine phosphinate ligand is obtained by regioselective oxidation of the crown phosphine nickel(II) complex 2c with molecular oxygen. The X-ray structure of 3·H2O (space group P21/c) has been determined. Oxidation of the macrocyclic phosphinous acid nickel(II) complex 2a (P4 donor set) with H2O2/HCl or Br2 and subsequent demetallation affords the macrocyclic phosphinic acid 5. Reaction of its methylester 6 with thionyl chloride and subsequent reduction with LiAlH4 gives the novel macrocyclic PH functional tetradentate phosphine 8 in high yields.

Nucleophilic phosphanylation of ortho-fluorophenylacetic acid or ortho-fluorobenzylamine with PhPH2 using KOtBu as the base affords the hydrophilic tertiary phosphanes 3 and 4a with terminal CH2-COOH and CH2-NH2 substituents. The corresponding secondary phosphane ligands 2 or 5 may be obtained by Pd-catalyzed P-C coupling of ortho-iodophenylacetic acid with PhPH2 or selective nucleophilic phosphanylation of ortho-fluorophenylacetic acid. Novel phosphonatomethyl derivatives 7a, 7b of triphenylphosphane have been obtained in a two stage synthesis using ortho-iodobenzylchloride or meta-iodobenzylbromide as starting materials. Arbusov reaction with P(OEt)3 and Pd-catalyzed P-C coupling reactions with Ph2PH gave the esters 7a, 7b. Purification of 7a was achieved via its BH3 adduct 8a. Deprotection, hydrolysis and neutralisation with NaOH affords the water soluble sodium salts 9a,9b. α-Hydroxy and α-benzylamino derivatives 12 and 14 of ortho-diphenylphosphanobenzyl phosphonate (e.g. 7a) and the corresponding Me2P(O) analogs 13 and 16 are accessible in a straightforward manner by addition of (MeO)2P(O)H or Me2P(O)H to ortho-phosphanobenzaldehyde 11a or its benzaldimino derivative 15, respectively. An improved synthesis for 11a -11c has been developed. Reaction of 11a with the Wittig reagent Ph3P=C(H)COOEt and subsequent hydrolysis of the intermediate ester 17a affords ortho-diphenylphosphano cinnamic acid 17. The catalytical activity of 1,9a, 9b and related ligands in Suzuki-type coupling reactions has been investigated.

The triphenylphosphane derivatives 2a and 5, bearing one and two phosphonic ester groups, are accessible in high yields by consecutive Pd-catalyzed P–C coupling reactions of p-bromoiodobenzene with Ph2PH and PhPH2, respectively, and then with diethyl phosphite. Ester hydrolysis yields the highly water-soluble sodium salts of mono- and bis-phosphonated triphenylphosphane, 3a and 6, respectively. On reaction of the p- and m-fluorophenylphosphonic diethyl esters 7a, 7b with Ph2PK and subsequent ester hydrolysis the isomeric disodium (diphenylphosphano)phenylphosphonates 3a, 3b were obtained. The X-ray structure of Ph2P(C6H4–m-PO3Na2) · 5.5 H2O · iPrOH (space group Cmc21) has been determined. In the solid state, it forms a layer structure with hydrophilic (PO32–, H2O, iPrOH) and hydrophobic (Ph2P) compartments, in which the PO32– anionic groups are not engaged in coordination of the sodium cations.

On reaction of chloromethylchlorophosphines Cl(R)P–CH 2 –Cl with Pd(Ph 3 P) 4 the C–Cl bond is selectively activated by oxidative addition to Pd(0), unusual dipalladium complexes with P–Cl functional η 2 , μ 2 -{CH 2 -P(R)Cl} bridges being formed with high diastereoselectivity. The X-ray structure of 3a (R= t Bu) reveals a chair-shaped Pd 2 P 2 C 2 six-membered ring system with the substituents (Cl, t Bu) at the two m 2 -P atoms in cis -position.

Diprimary and disecondary bis(phosphinoethyl)amines RN[(CH2)2–PHR′]2 (R=H, nBu, p-Tol; R′=H, Ph) (1a–1c, 2a) in addition to azaphosphorinanes (1d, 1e) are accessible by alkylation of PH3 or primary phosphanes with bis(chloroethyl)amines in the superbasic medium DMSO/KOH. Sequential P-methylation and N,P-silylation of 1a yields H–N[(CH2)2–PHMe]2 (2b) and the N- and P-trimethylsilyl derivatives Me3Si–N–[(CH2)2–PHMe]2 (3a) and Me3Si–N[(CH2)2–P(SiMe3)Me]2 (3c). With C7H8Mo(CO)3 the potentially tridentate P2N hybrid ligands 1a, 1b (L) form kinetically labile complexes fac-Mo(CO)3(L) (4a, 4b). Eight membered chelate complexes cis-Mo(CO)4(L) (4c, 5a) are obtained on reaction of 1b and 2b (L) with C7H8Mo(CO)4, the ligands L acting as P,P-bidentates. The X-ray structure of 4c (space group Pbca) reveals a distorted eight membered chelate ring system. By periphery reactions (P-metallation, N-protonation and complexation with borane) a series of derivatives (4d, 5b–5d) of 4c and 5a are accessible. A complex of a bidentate ligand with terminal azaphosphorinane units (6b) is obtained by alkylation of 4d with nBuN[(CH2)2Cl]2. Attempts to form a twelve membered tetradentate macrocycle by template mediated PH/CC addition of divinylphenylphosphine to 4a, 4b failed, however. The X-ray structure of the template 7a (space group P21/c) formed initially from 4a shows the PhP(CHCH2)2 ligand to be in cis-position to the diprimary phosphine which is coordinated to molybdenum via its P-atoms forming a folded eight membered ring system.

Chiral- and multiply-carboxylated phosphanes and phosphanyl derivatives of benzoic and phthalic acids (1−9) are accessible in high yields by nucleophilic phosphanylation of potassium or lithium salts of commercially available fluorobenzoic and 3-fluorophthalic acids with Ph2PH, Ph2PK, PhPLi2 Ph(K)P−(CH2)3−P(K)Ph in superbasic media (DMSO/KOH) or in THF and DME. The hitherto unknown phosphanylphenylacetic acids (10−13) and phosphanylbenzylamines RR′P−C6H4−CH2− NH2 (14−19, R, R′ = H, Me, Ph) with unsubstituted amino groups were also synthesized by this method. The diphenylphosphanyl derivatives 14−16 (R, R′ = Ph) are accessible by an alternative method involving LiAlH4 reduction of the phosphanylbenzonitriles (20−22), which were obtained in high yields by nucleophilic phosphanylation of the corresponding fluoro- or chlorobenzonitriles. The novel bidentate phosphanylbenzonitrile 23 has also been obtained using this synthetic route. All compounds were completely characterized by elemental analysis, NMR spectroscopy, and mass spectrometry.

Reaction of the chloromethylchlorophosphines R(Cl)P-CH2-Cl (R = Cl, tBu, C6H11, NEt2, NPh2) (L) with C7H8Mo(CO)4 or (CO)5W(Py), (CO)6W and (CO5W(THF) yields the complexes cis-Mo(CO)4L2(2a - 2e) or (CO)5 WL (3a - 3c), respectively, in high yields. The palladium(II) complexes PdCl2L2 (4a - 4c) are obtained on treatment of 1a, 1b and 1e with 1,5-cyclooctadiene palladium(II) chloride or anhydrous palladium(II) chloride in a homogeneous or heterogeneous reaction, respectively. 4a - 4c are formed as a mixture of cis- and trans-isomers. The 13C {1H} NMR and 1H NMR spectra of 2a - 4c have been analysed, the trans-structure of 4c could be assigned to the predominant isomer. The X-ray structural analysis of 4c (triclinic, space group Pl̅) reveals a trans-square planar coordination at palladium with an antiperiplanar arrangement of the bulky tBu substituents at the phosphorus atoms. Electronic (ƩXi Mo) and steric ligand parameters (θ) are given for the chloromethylchlorophosphines R(Cl)P-CH2-Cl (R = Cl, tBu, C6H11, NEt2, NPh2).

Chloromethylchlorophosphines R(Cl)P-CH2-Cl (R = C6H11, sec-C4H9, 2,4,6-R′3C6H2; R′ = tBu, iPr) with bulky substituents (1a - 1d) have been prepared by treatment of Cl2P-CH2-Cl with organolithium compounds RLi (R = 2,4,6-R′3C6H2) or Grignard reagents RMgX (R = C6H11, sec-C4H9). For the less bulky phenyl derivative Ph(Cl)P-CH2-Cl (1i) a protected group two stage synthesis has been developed employing Et2N(Cl)P-CH2-Cl as an intermediate. Si-N cleavage reactions between Cl2P-CH2-Cl and R2N-SiMe3 or nucleophilic substitution with Ph2NH yield the amino derivatives R′2N(Cl)P-CH2-Cl (R′ = Ph, Et, iPr) (1e, 1g, 1h). The chloromethylbromophosphines R(Br)P-CH2-Cl (R = Br, C6H11) have been obtained by halogen exchange in 1 and 1a with MgBr2 etherate. 1a, 1e, 1g and 1h exist preferably in an antiperiplanar conformation with respect to the P-C(H2) bond as inferred from the analysis of the 1H(CH2)-NMR spectra. Temperature dependent 1H and 13C {1H} NMR spectra indicate restricted rotational processes in 1h. On reaction of 2a with Fe2(CO)9 the η2,μ3-phosphaalkene cluster 3 is obtained, while with 2b (R = 2,4,6-iPr3C6H2) the μ3-phosphinidene cluster 4 is formed. Reductive dehalogenation of 1c (R = 2,4,6-tBu3C6H2) affords the phosphaalkene complex 6 in addition to the 2,3-dihydrobenzo[b]phosphole complex 5. Treatment of the iron carbonyl complex 7c with Fe2(CO)9 in a 1:1 molar ratio at elevated temperatures leads to a novel μ2-phosphido complex 7b with an ortho-metallated Ph2N substituent.

Tertiary phosphines Ph 2 OAr and PhP(Ar) 2 containing mono- and disubtituded aromatic ring systems Ar (ArC 6 H 4  and C 6 HXY; X, YMe, OH, NH 2 , COOH, COOMe and SO 3 Na) are accessible in good yields by Pd(O)-catalyzed cross coupling reactions between diphenylphosphine or phenylphosphine and substituted aryliodeds IC 6 H 4 -X or IH 3 -XY in organic solvents (dimethylacetamide, acetonitrile, methanol) using organic amines or potassium and sodium acetate as bases. If the primary phosphine is employed in the appropriate stoichiometric ratio, functionalized secondary phosphines, e.g. Ph(H)PC 6 H 4 - p -SO 3 Na, may be obtained selectively.

The secondary phosphines R(Ar*)PH(R = Me, iPr, Ph, Mes, Ar*) (2a-2h) with bulky aromatic substituents Ar* (Ar* = 2,3,6-R′ 3C6H2, R′ = iPr, tBu) are obtained in good yields by reaction of RPCl2, PCl3, PBr3 or Ar*P(Cl, Br)2 with 2,4,6-tBu3C6H2Li or 2,4,6- iPr3C6H2MgBr and subsequent reduction of the intermediate halophosphines R(Ar*)PX(X = Cl, Br) with LiAlH4. The X-ray structural analysis of Ph(2,4,6-iPr3C6H2)PH (2g), space group P1, shows P-C-distances of 1.824(1) and 1.838(1)Å. The lithium derivatives of 2a-2c are monomeric in solution as indicated by the 1 :1 :1 : 1-quartet 7L i - 31P fine structure of the 31P {1H} NMR signals at low temperatures. 2a-2c and 2f-2h form Ni(0) and Fe(0) complexes (CO)3NiL (6a-6f) and Fe(CO)4L (7a-7d), respectively. The Tolman electronic parameters of the bulky ligands are almost identical. Within the series 2a-2h the spatial shielding of the P atoms has been estimated using advanced molecular modeling techniques. The bulky ligand 2c forms coinage metal complexes [C u(CH3CN)2(2c)2] [PF6] (8), Cu2Cl2(2c)2 (9) and Cl-Au(2c) (10). While 10 is monomeric in solution, in the solid state it forms pairs of head to tail oriented monomers with almost linear Cl - Au - P skeletons (Cl - Au - P 175.47(9)°) as shown by an X-ray structural analysis.

Reaction of P-H or P-Cl functional methylenebisphosphanes X (R )P - CH2-P(R)X (X = H, Cl; R = Ph, tBu) with cyclopolyphosphanes (R′P)„ (R′ = Ph, tBu, Me; n = 4, 5) affords cyclocarbatetraphosphanes CH2(RP)2(R′P)2 (2-6 ). The cyclopolyphosphanes (R′P)„ em ployed may be synthesized in situ by reaction of chlorophosphanes R′PCl2 with primary phosphanes R′PH2, LiH or magnesium, respectively, providing a single stage synthesis for unsymmetrically substituted cyclocarbatetraphosphanes.

Monocationic amphiphilic tertiary phosphines [RMe2N-(CH2)n-PR′2]+ X− (1–3) obtained by P-alkylation of the corresponding primary phosphines (R′  H) form stable tungstencarbonyl-, Rh(I)-olefin- and square planar Pd(II)-complexes (4–8a). Stepwise protonation of [Me2N-(CH2)2]3P (9) by Ph3P · HBr or aqueous HCl affords tricationic tertiary phosphine ligands, e.g. {[HMe2N-(CH2)2]3P}3+ 3X− (13, 13b) and the phosphonium salt {[HME2N-(CH2)2]3P-H}4+ 4Cl− (13a). The pKa-values 9.67, 8.86, 7.92 and 1.9 have been obtained by titration of 13a with NaOH in aqueous solution. Highly charged Pd(II)-complexes (16a, 16b) with extreme water solubilities were obtained from 13 and PdBr2 or by N-protonation of cis-PdCl2(9)2 with HCI. The crystal structures of 13 · 0.5H2O and {trans-{[HMe2N-(CH2)2]3P})2PdCl2}6+ 6Cl−· 2MeOH (16b) (space group C2/c) have been determined. While the P( … N)3 skeleton of the trication in 13 is almost flat, it is folded back on coordination to palladium(II) in 16b.

Primary and secondary aminoalkylphosphanes R2N-(CH2)m-PH2 (R2 = Me2, nBu2, C5H10, C4H8O, 2-(1-Methyl-2-pyrrolidinyl); m = 2, 3, 6, 10, 11; 1-6) or [R2N-(CH2)m]2PH (7, R2 = C5H10; m = 2) are accessible by aminoalkylation of PH3 with ω̃ -chloroalkylamines R2N-(CH2)m-Cl in the superbasic medium DMSO/KOH (DMSO = dimethylsulfoxide). By selective N-quaternization of 1, 2, 4-6 with R'I (R' = Me, CnH2n+1; n = 6-8, 12, 16, 18) in the two-phase system CH2Cl2/H2O novel primary phosphanes [R'R2N-(CH2)m-PH2]+I- (11-16f) with quaternary ammonium groups in the alkyl side chain are obtained. The water solubility of 11-16f decreases with increasing chain length (n) of R′ 11 (R = R' = Me; m = 2) shows a trans conformation at the C2H4 bridge according to an X-ray structural analysis. Protonation of 1, 2, 4, 5 with HCl affords the water-soluble hydrochlorides [HR2N-(CH2)m-PH2]+Cl- (19-22). The cationic primary phosphanes 11-16f are stable towards oxygen. By oxidation of 11 with one or two equivalents of H2O2 the primary phosphane oxide [Me3N-(CH2)2-P(O)H2]+I- (23) or the phosphonous acid [Me3N-(CH2)2- P(O)(OH)H]+I- (23a) are formed. Hofmann degradation of 11 or 16c with KOH yields phosphirane in good yields. Reaction of 1, 2, 4-6 (L) with Fe2(CO)9 at ambient temperature yields stable complexes (CO)4FeL (26-30). Under more rigorous conditions Fe3 clusters (31, 32) with free R2N groups are obtained.

On reaction of disecondary methylenebisphosphanes H (R)P-CH2-P(R)H and H(tBu)P-CH2-P(R)H(R = Ph, 2,4,6-R'3C6H2, R' = Me, Et, iPr, tBu) with excess Fe2(CO)9, Ru3(CO)12 and Os3(CO)12 the hydrido clusters M3(CO)9(μ2-H )[μ2-P(R, tBu)-CH2-P(R,tBu)H] (M = Fe, Ru, Os) (3a -3j) are formed in addition to bimetallic phosphido com plexes (5a -5g) and clusters (4a - 4f) with [μ2-P(R,tBu)]2CH2 bridges. At higher temperatures cleavage of the P-C-P skeleton in 3a, 3b, 3d and 3h is accompanied by activation of the terminal C-H bonds of ortho-substituents R' (Et, iPr, tBu), phosphinidene clusters (8a, 8b, 8d and 8e) containing 2,3-dihydrobenzo[b]phosphole ligands being formed. Cluster com pounds Fe3(CO)9[μ3-P(R, tBu)][MeP(H)R] (7a - 7c) with secondary phosphane ligands could be identified as intermediate products. The X-ray structural analysis of Fe3(CO)8(μ2-H)2L(L = 1,3,3-trirnethyl-6,8-di-tert-butyl-2,3-dihydrobenzo[b]phosphole) (8e) shows a trigonal pyramidal Fe3P skeleton with the 2,3-dihydrobenzo[b]phosphole ligand in axial position. Metal-assisted fragmentation of the methylenebisphosphanes H(R )P-CH2-P(R)H(1f, 1g) with less bulky aromatic substituents (R = Ph, 2,4,6-Me3C6H2) affords bis-μ3-phosphinidene clusters Fe3(CO)9(μ3-PR)(μ3-PR') 11e (R = R' = 2,4,6-Me3C6H2) or 11f (R' = Ph, R = Me) and the phosphaalkene cluster Fe3(CO)9(μ3-PPh)(μ3, η2-P(Ph)=CH2) (13b), respectively. If 1g is treated with Fe2(CO)9 in an 1:2 molar ratio at elevated temperatures cleavage of the P-C-P skeleton leads to 14, a bimetallic complex with different phosphido bridges [μ2-P(R )H and μ2-P(R)Me]

Water soluble tertiary phosphanes 2, 7, 10–17 with sulfonated aromatic substituents p- C6H4-SO3K and 2,4-C6H3(SO3K)2 can be obtained in good yields by nucleophilic aromatic substitution of fluorine in p-F-C6H4-SO3K (1) or F-C6H3-2,4-(SO3K)2 (5) with PH3 or primary and secondary phosphanes in the superbasic medium dimethyl sulfoxide (DMSO)/KOH(solid). The first water-soluble secondary phosphane HP[C6H3-2,4-(SO3K)2]2 (6) having sulfonated aromatic substituents can be obtained if 5 is reacted under similar conditions with PH3. Highly sulfonated phosphanes (7–9) with remarkable solubilities in water are formed upon reaction of 6 with F-C6H5, nBuBr or C6H5-CH2-Br, respectively, in the superbasic medium. The resulting compounds have been identified by their 1H, 13C(1H and 31P(1H)NMR spectra. X-Ray structural analysis of P(p- C6H4-SO3K)3 · KCl · 0.5H2O shows C3 symmetry for the trianion of 2 with the P CP bond angles (103.5(2)°) and PC bond lengths (1.843(4) A) being almost identical to those in Ph3P.

Synthesis and Coordination Chemistry of Hemilabile P,N-Hybride Ligands with Terminal 2-Pyridyl Donor Groups* P,N-hybride ligands 1–7 containing terminal 2-pyridyl donor groups have been obtained by base-catalyzed addition of diphenylvinylphosphane or 2-vinylpyridine to primary or secondary phosphanes [2-Py-(CH2)2-PR′H (R′ = H, Ph), HMeP-(CH2)3-PMeH] or by alkylation of organolithium phosphides, R2P-(CH2)3-PMeLi or 2-Py-(CH2)2-PR′Li (R = Ph, iPr; R′ = H, Ph), with 2-(2-chloroethyl)pyridine or di-tert-butylphosphetanium bromide. Upon reaction with NiBr2 3 H2O or K2MCl4 (M = Pd, Pt) the phosphanes (L) of type 2-Py-(CH2)2-P(R′)-(CH2)m-PR2 (1, 3, 6) form square planar Ni(II), Pd(II), and Pt(II) complexes of composition MX2(L) (10–14). With NiBr2 and K2MX4 the tripod type phosphane 2 forms square pyramidal complexes [MX(2)]X (M = Ni, Pd; X = Cl, Br; 15, 16). An X-ray structural analysis of [NiBr(2)]+Br− (15) reveals a distorted square pyramidal coordination geometry at Ni(II), the 2-Py donor being in apical position with a long NiN bond [2.270(15) A]. The tetradentate ligand 7 forms Ni(II), Pd(II), and Pt(II) complexes MX2(7) which for M = Pd, Pt show dynamic behaviour by exchange of the terminal Py donor groups. With [RhCl(COD)]2 the tridentate ligands L (1 and 3) yield complexes of composition RhCl(L) (20, 21). The structure of 20 has been determinated by X-ray diffraction. The ligand 3, acting in a tridentate manner, is coordinated to Rh(I) in a distorted square-planar arrangement with a normal RhN distance [2.145(3) A].

On reaction of the chloromethylchlorophosphines R(Cl)PCH2Cl (R  Cl, iPr, tBu, NEt2, N(iPr)2, NPh2, O-2,6-iPr2C6H3; 1–7) with diiron enneacarbonyl the iron carbonyl complexes 8–14 are formed in good yields. Dehalogenation of the phosphine complexes 9–14 with Fe2(CO)9 affords the phosphaalkene clusters [μ3,η2-RP CH2]Fe3(CO)10 (15–19). If Fe3(CO)12 is used instead of Fe2(CO)9 for the dehalogenation of 10- 13 phosphinidene phosphaalkene clusters [μ3,η2-RPCH2][μ3-PR]Fe3(CO)9 (25–28) and binuclear complexes with bridging RPCH2 ligands (21–24) or α-metallated phosphido-phosphine bridges (20) (μ2-P(R) CH2P(R)CH2 (R  tBu)) are obtained. The crystal structure of 18 (R  Ph2N; space group P21/n) shows the phosphaalkene ligand to be twisted about the P C bond (dihedral angle N(1)P(1)C(31)Fe(3) 177.5(1)°) the CH2 group being pyramidalized (H(31)C (31)H(32) 104.0°). In the binuclear complex 20 (space group P21/c phosphinoalkyl unit of the μ2,η3-P (R)CH2P(R)CH2 ligand spans the FeFe bond forming a distorted four-membered FePCFe ring with a short PC bond (P(2)C(12) 176.5(4) pm). The PCP donor set is coordinated to Fe(1) within a strained four-membered P2CFe chelate ring. Then η1,η2-RPCH2 ligand (R  N(iPr)2) in 23 with a short PC bond (P(1)C(1) 173.4(4) pm) bridges two iron atoms, a distorted, almost planar Fe2P2 ring being formed.

On reaction with diironenneacarbonyl the tertiary primary phosphine Ph 2 PCH 2 PH 2 yields the hydrido cluster (μ 2 -H)(μ 2 -PHCH 2 PPh 2 )Fe 3 (CO) 9 ( 4 ). If excess of Fe 2 (CO) 9 is employed in this reaction the PCP-bridged Fe 4 -cluster 5 is formed with loss of hydrogen. At higher temperatures rearrangement of the Fe 3 (Fe)P-skeleton and phosphinidene fragmentation of the PCP backbone of 5 affords the Fe 4 P spiro compound (μ 4 -P)(μ 2 ,η 2 -PPh 2 CH 2 )Fe 4 (CO) 14 ( 6 ) with an edge bridging Ph 2 CH 2 unit. X-ray structural analysis of 6 (space group P 2 1 / n ) reveals a distorted Fe 4 P spiro type arrangement. The iron atoms Fe(1) and Fe(3) and the Ph 2 PCH 2 ligand with a short PC bond (P(1)C(1) 178.6(7) pm) form a distorted almost planar four-membered Fe 2 PC ring system.

On treatment of the Me 3 Si-functional 1,3,2σ 5 λ 5 -dioxaphospholane ( 1 ) with boron trichloride the novel mixed boric–phosphinic acid ester ( 3b ) of perfluoropinacol is formed in a ring-opening reaction, instead of the expected mixed anhydride ( 3a ) with pentacovalent phosphorus.

Cationic phosphine ligands containing m-guanidinium phenyl substituents {Ph3-nP[C6H4-m-NHC(NH2)(NMe2)]n}n+ nCl- (n = 1−3) (17a−c) have been obtained by addition of dimethylcyanamide to the amino gr...

Reaction of halogen functional methylenebisphosphines 1 XRP–CH2–PRX (X = Cl, Br) with excess Fe2(CO)9 affords μ3-phosphinidene clusters (5) containing phosphaalkene ligands R–P=CH2. The fragmentation of the P–C–P skeletons in 1 proceeds stepwise, phosphide complexes 2 and novel Fe3 clusters 3 with RP–CH2–PR bridging units being formed as intermediates of the oxidative addition reductive elimination process. The X-ray structural analysis for 5b (R = NEt2) reveals an Fe3(CO)9PR butterfly core to which the phosphaalkene ligand R–P=CH2 (P=C bond length 1.766(4) A) is coordinated in a μ3,η2-manner. In case of methylenebisphosphines 1 with bulky substituents (R = 2,4,6-iPr3C6H2) the phosphinidene fragmentation of the P–C–P skeleton is accompanied by the formation of 2,3-dihydrobenzo[b]-phosphole ligands.

Novel Syntheses and Reactions of Phosphetanium Salts with a Planar Skeleton Cleavage of the P–Si bond of silylphosphanes R2P-SiMe3 (R = iPr, tBu, 2,4,6-Me3C6H2) with excess 1,3-dihalogenpropanes X–[CH2]3–X (X = Br, I) affords phosphetanium salts (3) in good yields. These strained four-membered ring systems are also obtained by alkylation of secondary phosphanes R2PH with X–[CH2]3–X followed by deprotonation of the intermediate phosphonium salts [R2P(H)—[CH2]3–X]+ X- (R e.g. tBu; X = Br, 7b). Silylphosphanes and secondary phosphanes with less bulky substituents preferably form open-chain phosphonium salts with [CH2]3–X or allyl substituents in these reactions. X-ray structural analysis of (3h) reveals planar geometries for the PC3 skeletons of the cations. The reactivity of 3b towards different types of nucleophiles [F-, NH2-, OH-, OR-, Fe(CO)2Cp-, NaN(SiMe3)2, RR′PLi] has been studied. Reaction with CsF or NaNH2, leads to a stable monofluoro or monoamino phosphorane, respectively, with cyclic four-membered PC3 skeletons. In all other cases opening of the phosphetanium ring system occurs leading to derivatives with R2P—[CH2]3 terminal groups. Bidentate and polydentate ligands, e.g. 19–25, with bulky substituents in terminal position have been synthesized in high yields by cleavage of 3b with mono- and bifunctional lithium phosphides. By deprotonation of 3b with MeLi the cyclic ylide 14 is formed. Treatment with acetone or benzaldehyde leads to the unsaturated open-chain phosphane oxides 15a or 15b in a Wittig-type reaction.

Dehalogenation and Regioselective Phosphinidene Fragmentation of Unsymmetrically Substituted Methylenebisphosphanes RXP-CH2-PXR′ with Fe2(CO)9 Reductive dehalogenation of the unsymmetrically substituted methylenebisphosphanes RXP–CH2-PR′X [X = Cl, Br; R = tBu, NEt2; R′ = 2,4,6-R”3C6H2 (R” = Me, tBu), NEt2, 2,6-iPr2C6-H3O, 2,6,4-tBu2MeC6H2O] with Fe2(CO)9 affords, depending on the reaction conditions employed, phosphido complexes [μ2-(RP-CH2-PR′)]Fe2(CO)6 (2) or phosphaalkene clusters (μ3-PR′)(η2,μ3-PRCH2)Fe3(CO)9(6) or [(μ-PR)(η2,μ3PR′CH2)]Fe3-(CO)9 (7), respectively, by regioselective phosphinidene fragmentation of the RP–CH2-PR′ skeletons. The unstable cluster compounds [μ3-PR′–CH2–PR)]Fe3(CO)9 (4) are formed as intermediate products. X-ray structural analysis of 6c (R = tBu; R′ = NEt2) reveals a flat butterfly (μ3-PR)Fe3 structure bridged by the phosphaalkene ligand tBuP = CH2 with a short P = C distance [177.2(4) pm].

Treatment of the bifunctional chlorophosphine R2P-CH2-PRCl (R = tBu) with diironenneacarbonyl affords the binuclear complex Fe2(CO)6[μ2,η3-P (tBu )-CH2-P(tBu)-CMe2-CH2] (2) by oxidative addition reaction and metallation of one of the tBu groups within the tBu2P - CH2 unit. At elevated temperatures 2 eliminates isobutene, the phosphido complex Fe2(CO)6[(μ2-P(tBu))2CH2] (3) being formed. The crystal structure of 2 (space group P1̄ with a = 8.663(3), b = 10.849(4), c = 14.618(6) Å, α = 103.02(2), β = 96.32(3), γ = 112.77(2)°, Z = 2) reveals a binuclear complex with a P(tBu) - CH2- P(tBu) - CMe2- CH2 ligand backbone spanning the Fe - Fe bond via a phosphido (μ2-P(tBu)(CH2)) and a phosphinoalkyl (μ2-P(tBu)-CMe2-CH2) bridge. A strained, four-membered P2CFe ring is formed through coordination of the P - C - P donor set to Fe(2).

Reductive dehalogenation of the bifunctional methylene bridged halogenphosphines XRP-CH2—PRX (X = Cl, Br; R = iPr, tBu, 2,4,6-R′3C6H2 (R′ = Me, iPr, tBu), N(SiMe3)2 and 2,6,4-tBu2MeC6H2—O) with diironenneacarbonyl affords phosphido complexes with strained RP—CH2—PR backbones, Fe2(CO)6[(μ2-PR)2CH2] (8a-8g). X-Ray structural analyses of the 2,4,6-iPr3C6H2 (8d) and 2,6,4-tBu2MeC6H2—O derivatives (8g) reveal that the Fe2P2C skeletons have remarkably small P—C—P angles (83,7(4)° (8d), 78,6(1)° (8g)). The dehalogenation of XRP—CH2—PRX with Fe,(CO)9 is preceded by the formation of iron carbonyl complexes (RXP—CH2—PRX)[Fe(CO)4]n (n = 1, 2). For derivatives with bulky substituents R complex formation proceeds diastereoselectively. In case of 3 b the diastereoisomers could be separated and a crystallographic examination of the racemic form showed that the P—C—P backbone possesses C2 symmetry with an approximately trans conformation of the P—C—P fragment. The P-atoms occupy the equatorial position within the Fe(CO)4P units. The chloro-phosphido bridged complex Fe2(CO)6(μ2-Cl)(µ2-PR—CH2—PRCl—Fe(CO)4) (4a), formed by oxidative addition of a P—Cl bond to Fe(0), or diphosphiranes and their complexes [(RP)2CH2][Fe(CO)4]n (n = 0-2; 5-7) have been isolated as intermediates of the XRP-CH2—PRX dehalogenation. The diphosphiranes 5 were synthesized independently by reduction of the halogenphosphines XRP—CH2—PRX with lithium or magnesium. An X-ray examination of 4a showed that it contains a μ2-PR—CH2—PRCl backbone which bridges Fe2(CO)6(μ2-Cl) and Fe(CO)4 units, the P—C—P angle being remarkably large, 127,3(1)°.

The reaction of N-trimethylsilylphosphine imines, Me3SiN=PR1R2R3, and Me3SiN=P(R1R2)—N=PR1R2R3 (R1, R2, R3 = hydrocarbon or NR, groups) with the fluorophosphoranes PhPF4 and Ph2PF3 and with phosphorus trichloride has furnished phosphine iminophosphonium organofluorophosphates, involving the anions [PhPF5]- or [Ph2PF4]-, and mono- or dichlorophosphino diphosphazenes, respectively. The characterization of these compounds by 1H, 19F and 31P NMR spectroscopy is described.