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The gas-phase structure of 1-adamantylphosphine has been determined by electron diffraction, supplemented with data from ab initio and DFT calculations. The adamantyl fragment was modeled with local C 3v symmetry and the phosphino group was found to be in a position almost bisecting a mirror plane of the adamantyl group, giving the molecule overall approximate C s symmetry. There is a small displacement of the C–P bond from the local threefold axis of the adamantyl group. Geometry optimizations were also performed for bis-(1-adamantyl)phosphine (C 1 point-group symmetry) and tris-(1-adamantyl)phosphine (C 3 symmetry), demonstrating extremely crowded environments around the phosphorus atoms leading to adamantyl groups that were much less symmetric. The adamantyl groups were also found to twist by a significant amount to minimize the strain.

The reaction of linear push–pull enamines bearing a methyl group at the α-position with a set of trifluoromethylated carbonyl compounds was investigated. It has been found that the reaction proceeds at the methyl group of the enamines. The first computational study of the reaction between push–pull enamines and strong electrophilic reagents was reported. Out of three pathways considered DFT and MP2 calculations support ene-mechanism previously suggested based on experimental results only.

19F and 31P NMR spectroscopy were used to study the kinetics of the hydrolysis of LiPF6 in the homogenous solvent system propylene carbonate (PC)—dimethyl carbonate (DMC)—H2O. It was found that the main products of the hydrolysis are HF, LiPO2F2 and Li2PO3F. The content of POF3 and PF5 was negligibly low. We set up a hypothesis that the main factor determining the rate of the process is the so-called ‘secondary’ catalytic effect, caused by solvated H+ ions.

Bis(dimethylphosphino)naphthalene, 1,8-(PMe 2 ) 2 C 10 H 6 (dmpn), reacts readily with Ru 3 (CO) 12 or Ru 3 (μ-dppm)(CO) 10 with replacement of one of the PMe 2 groups by H to give Ru 3 (CO) 12 − n {PMe 2 (nap)} n ( n = 1 2 , 2 3 ) or Ru 3 (μ-dppm)(CO) 9 {PMe 2 (nap)} 4 ; the complex Ru 3 (CO) 10 (dmpn) 1 is obtained only in small amount. Thermolysis of 2 or 4 gives Ru 3 (μ-H) 2 {μ 3 -PMe 2 (C 10 H 5 )}(μ-dppm) n (CO) 8-2n ( n = 0 5 , 1 6 , respectively) containing μ 3 -naphthalyne groups.

Reactions of Os3(CO)12 with 1,8-bis(diphenylphosphino)naphthalene (dppn) are described. Crystallographically characterised complexes isolated from a reaction carried out in refluxing toluene are Os3(μ-H)2{μ-PPh2(nap)PPh(C6H4)}2(CO)6 (1), Os3(μ-H){μ3-PPh2(nap)PPh(C6H4)}(CO)8 (2) and Os2(μ-PPh2){μ-PPh2(nap)}(CO)5 (3) (nap=1,8-C10H6), while at r.t. in the presence of ONMe3, only Os3(CO)11{PPh2(1-C10H7)} (4) was isolated. While 1 and 2 contain ligands formed by metallation of a Ph group of dppn, as found also in complexes obtained from dppn and Ru3(CO)12, ligands in 3 and 4 are formed by cleavage of a P-nap bond, not found in the Ru series.

Michael I. Bruce, Paul A. Humphrey, Sakir Okucu, Reinhard Schmutzler, Brian W. Skelton and Allan H. White

Chiral racemic 1,8-bis( tert -butylphenylphosphino)naphthalene oxide ( 2a ) was resolved into enantiomers by fractional crystallization of its diastereomeric adducts 3a with (+)-(2 S ,3 S )-di- O -benzoyl tartaric acid (DBTA), followed by neutralization. Racemic 1,8-bis( tert -butylphenylphosphino)naphthalene ( 1a ) was oxidized with sulfur to two isomers of 1,8-bis( tert -butylphenyl-phosphino)naphthalene monosulfide, rac - 4a and rac - 4a ′, or 1,8-bis( tert -butylphenylphosphino)naphthalene disulfide, rac - 5a . The compounds were characterized by NMR spectroscopy ( 1 H, 31 P, 13 C). Crystal structures were determined by the X-ray method for (−)- 3a, rac - 4a , rac - 4a ′ and rac - 5a ; this allowed the determination of the absolute configuration ( S , S ) for the more soluble adduct (−)- 3a . It was found that rac - 1a undergoes partial epimerization in boiling xylene to give the meso form.

The conformations and vibrational spectra of 2-benzylphenol have been analysed within the framework of scaled quantum mechanics. It is shown that the solid-state conformation of the 2-benzylphenol molecule corresponds to one of four potential energy minima predicted by non-empirical quantum chemical calculations for the isolated molecule. In the molten state and in diluted CCl4 solutions of the title compound this conformer coexists with another two spectroscopically detected conformations. The presence of several conformers gives rise to the observation of the corresponding number of vsCH2 and vasCH2 bands in the IR spectra, thus providing experimental evidence of the conformational sensitivity of the vCH2 frequencies. It is shown that vCH2 wavenumbers of different kinds of molecules, containing diphenylmethane fragments, are determined by the dihedral angles between the planes of the aromatic rings and the plane of the connecting methylene bridges, except for the case of short intramolecular contacts with the participation of the methylene protons.

Chemical shifts, δ( 19 F ), were recorded for solutions of LiBF4 in diethyl carbonate (DEC), dimethyl carbonate (DMC), tetrahydrofuran (THF), 1,2-dimethoxyethane (DME), γ-butyrolactone (GBL), propylene carbonate (PC) and water. The δ( 19 F ) values of the tetrafluoroborate anion were obtained by extrapolation to infinite dilution. A correlation between δF and both dielectric constants and dipole moments of the solvents has been found.

This paper describes the preparation of 1,8-bis[bis(dimethylamino)phosphino]naphthalene (2a) and the attempted preparation of its isopropyl analogue 2c, which led to the formation of 1-naphthyl-bis(diisopropylamino)phosphine (4), and to other unidentified products. The X-ray structures of 2a and 4 are discussed in comparison to those of 1,8-bis[bis(diethylamino)phosphino]naphthalene (2b) and 1-naphthyl-di-tert-butylphosphine (5), respectively. In the structures of 2a, 2b and 4 the (R2N)2P groups (R=alkyl) are eclipsed with respect to the naphthalene plane, whereas the R2P groups (R=alkyl or aryl) in 5, as in 1,8-bis(diorganophosphino)naphthalenes in general, adopt a conformation between bisecting and eclipsed. Furthermore, the reactions of 2a and 2b with BX3 ether adducts (X=F, Cl) are described, which furnished the heterocyclic [σ3P–σ4P+]-diphosphorus compounds, 1-dimethylamino-2-bis(dimethylamino)-, 1-diethylamino-2-bis(diethylamino)- and 1-chloro-2-bis(diethylamino)-1-phospha-2-phosphonium-acenaphthene (6a, 6b and 7b); the first examples of the 1,2-dihydro-1,2-diphospha-acenaphthene ring system. The X-ray structures of 6a and 7b display a relief of strain compared to the parent bis-aminophosphines 2a and 2b, quantified by negative splay angles [−7.89° (6a) and −9.40° (7b); cf. +12.16° (2a) and +12.0° (2b)] and the bonded [225.38 (6a) and 223.16 (7b) pm] compared to the non-bonded phosphorus–phosphorus distances [311.9 (2a) and 311.7 (2b) pm]. A mechanism is discussed for the formation of 6b and 7b from 2b and gaseous hydrogen chloride.

The synthesis and characterization of the cis complexes L 2 Mo(CO) 4 with L = Ph 3 CPF 2 , Ph 3 CPH 2 , Ph 3 CP(H)Cl, Ph 3 CP(H)F, Ph 3 CP(NH 2 ) 2 and Ph 3 CP(H)Ph is described. The compounds were formed when norbornadiene tetracarbonylmolybdenum was allowed to react with two equivalents of L at room temperature, while, presumably due to their increasing steric hindrance, in the case of the ligands Ph 3 CP(H)t-Bu and Ph 3 C(H)PP(H)CPh 3 no reaction had taken place. The PC-bond of the unstable phosphine Ph 3 CPH 2 showed stabilization and, in contrast, the PC-bond of the stable phosphine Ph 3 CPCl 2 showed destabilization when the PMo-bond was formed. An X-ray structure determination of (Ph 3 CPF 2 ) 2 Mo(CO) 4 revealed short P–Mo bonds.

Syntheses and characterizations are described for C−H insertion products derived from 1,3-dimesityldihydroimidazol-2-ylidene (1) with acetylene, acetonitrile, methyl phenyl sulfone, and chloroform. In the reaction with acetylene, both acetylenic H-atoms are reactive so that 1 : 1 and 2 : 1 adducts can be obtained. The acetylene and methyl-phenyl-sulfone adducts are structurally characterized by means of single-crystal X-ray structure determinations. The reactions of 1,3,4,5-tetramethylimidazolidin-2-ylidene (8) with chloroform or chlorodifluoromethane are shown to yield 2-(dihaloalkyl)imidazolium salts that arise from a failure of the intermediate 2-protioimidazolium salt to capture the initially formed halocarbanion.

Triphenylmethyl fluoride 1 will effect chlorine–fluorine exchange in certain phosphorus chlorides. Exchange of chlorine for fluorine was observed only in σ 3 λ 3 (P)- and σ 5 λ 5 (P)-compounds, while phosphorus oxychloride as an example of a σ 4 λ 5 (P)-compound was unreactive towards 1 .

Chiral symmetric di- and trialkylphosphites, derivatives of (−)-borneol, (−)-menthol and (−)-1,2:5,6-di-O-isopropylidene-α-D-glucofuranose, were studied as starting reagents for the preparation of chiral organophosphorus compounds. The reaction occurs by asymmetric induction at the α-carbon atom of substituted α-alkylphosphonates. The stereoselectivity of the reaction depends on the structure of the starting compounds and the reaction conditions. The configuration of the alkylphosphonates was established by NMR spectroscopy, by transformation into α-hydroxyalkylphosphonic acids and by X-ray crystal structure analysis.

The E - and Z -isomers ( 1a,1b ) of 1,2-bis(fluorodimethylsilyl)-1,2-diphenylethene have been investigated by 1 H, 13 C and 19 F NMR spectroscopy, mass spectrometry and single crystal X-ray structure analysis. The NMR spectra of both compounds were markedly different, caused by the non-equivalence of all methyl groups and through non-bonding F–F interactions (through-space coupling) in isomer 1b . X-ray investigations reveal a widening of the CC-Si angles at the expense of Si–C–Ph; the CC bond of the Z -isomer is lengthened to 135.4(2) pm.

The reaction of phenyldifluorophosphine 1 with calcium hydroxide is an alternative route to form phenylphosphonous acid fluoride 2 . The reaction of 2 with methyl ketones, MeC(:O)R, leads to addition products of type PhP(:O) (F)C(Me)(R)OH. A single crystal X-ray structure determination is described for the adduct PhP(:O)(F)C(CH 3 ) 2 OH 8 obtained from phenylphosphonous acid fluoride 2 and acetone; hydrogen bonds of the form O-H… O-P are observed.

In the reaction of various 2,3-dihydro-1,3,2-benzodiazaphosphorin-4( 1 H )-ones with perfluorinated a-diketones, CF 3 C(:O)C(:O)R f an oxidative addition reaction with concomitant N -alkylation of the CH 3 (N) atom, and formation of tricyclic phosphoranes was found to take place. In one case no N -alkylation reaction was observed and a perfluoropinacolyl spirophosphorane was formed instead. The course of the reaction mainly depends on the steric demand of R f and the N -3 substituents of the benzodiazaphosphorinones.

The reaction of pentafluorobenzyl magnesium bromide with phosphorus trichloride in a 2:1 molar ratio led to the disubstituted product, bis(pentafluorobenzyl) bromophosphine 1 , which, upon reaction with lithium aluminium hydride, was converted to bis(pentafluorobenzyl) phosphine 3 . The reaction of 3 with oxygen led to bis (pentafluorobenzyl) phosphine oxide 4 . The reaction of 1,3 and 4 with di- μ -chloro-bis-[( η 6 -mesitylene) chloro-ruthenium (II)] 5 yielded the η 6 -mesitylene-phosphinedichloro-rutheniun (II) complexes 6–8 . Single-crystal X-ray structure determinations are described for the phosphinous acid-ruthenium(II) complex 8 and for the by-product 1,2 bis (pentafluorophenyl)ethane 2 , formed during the Grignard reaction of magnesium and pentafluorobenzylbromide. In 8 , the Ru-C bond lengths can be categorised as four short (219–222 pm) and two long (224–228 pm). A weak intramolecular P-OH···Cl contact (O···Cl, 304 pm) is observed.

The diorganophosphinous-N-(N′, N′, N″, N″-tetramethyl) guanidinides 1a and 1b and the organophosphonous-bis-N-(N′, N′, N″, N″-tetramethyl)guanidinides 2 and 3 are used as ligands towards carbonyls of zerovalent transition metals. In most cases coordination via phosphorus is observed. 1b and 2 act as PN-donors towards the (tetracarbonyl)molybdenum fragment, forming chelate complexes involving one five-membered ring. 3 acts as a PNN′-donor towards molybdenum carbonyls, forming a bicyclic chelate complex. X-ray structure determinations were performed for the octacarbonyldimanganese compound 7, the tricarbonylnickel complex 8 and the tetracarbonyliron derivative 10. The dimanganese compound 7 was found to be diaxially substituted with short MnC bonds but standard MnP bond lengths. The nickel compound 8 exhibited short PNi bonds, long NiC bonds and short CO bonds, consistent with enhanced π-back donation from metal to phosphorus. The coordination geometry at the iron atom in 10 was found to be trigonal bipyramidal with phosphorus in the axial position, strongly distorted towards square pyramidal.

For a series of (1-hydroxyalkyl)dimethylphosphine sulfides Me2P(S)C(OH)R1R2 the molecular structures have been determined. The crystallographic results obtained are as follows. Me2P(S)C(OH)Me2; monoclinic, P21/n, a = 10.910(3) A, b = 6.340(2) A, c = 11.886(3) A, β = 96.47(2)°, V = 816.9 A3, Z = 4. Me2P(S)C(OH)(CH2)5: orthorhombic, P212121, a = 8.683(3) A, b = 9.474(3) A, c = 12.730(3) A, V = 1047.2 A3, Z = 4. Me2P(S)C(OH)(Me)C(O)Me: orthorhombic, P212121, a = 7.664(3) A, b = 10.354(2) A, c = 11.838(3) A, V = 939.4 A3, Z = 4. Me2P(S)C(OH)(Ph)C(O)Ph: monoclinic, P21/n, a = 8.400(3) A, b = 10.343(3) A, c = 17.784(4) A, β = 101.97(3)°, V = 1511.5 A3, Z = 4. Me2P(S)C(OH)(H)C(O)(OH): triclinic, P1, a = 6.145(2) A, b = 11.268(4) A, c = 12.126(3) A, α = 110.64(2)°, β = 103.64(2)°, γ = 94.88(2)°, V = 750.4 A3, Z = 4. The principal values of the phosphorus nuclear magnetic shielding tensor have been determined by 31P solid-state CP MAS NMR spectroscopy. The similar structures of the compounds around the P atom...

The reaction of [Ru3(CO)10(μ-dppm)] (1) with secondary phosphines R2PH (R  tBu, 1-Ad) in heptane under reflux leads to th electron-deficient metal cluster complexes [Ru3(μ-CO)(CO)4(μ3-H)(μ-H)(μ-PR2)2(μ-dppm)] (R  tBu 4; R  1-Ad 5) in good yields. The reactions yield first the monosubstituted compounds [Ru3(CO)9(R2PH)(μ-dppm)] (R  tBu, 2; R  1-Ad 3), which could be isolated in yields up to 85% after 1 h in refluxing THF. The related reaction of 1 with the less bulky phosphine Cy2PH in heptane under reflux gave the new electronically saturated complex [Ru3(CO)6(μ-H)2(μ-PCy2)2(μ-dppm)] (7). In this case the intermediate [Ru3(CO)9(Cy2PH)(μ-dppm)] (6) could also be isolated. Compounds 4 and 5 seem to be coordinatively saturated, in that no reaction with carbon monoxide or dihydrogen was observed, either under normal conditions or under elevated pressure. The molecular structures of 4 and 7 were determined by single-crystal X-ray studies (dppm  Ph2PCH2PPh2; Ad  Adamantyl).

Synthesis and structural studies of the iron “sandwich” complex [Fe( η 5 -C 5 Me 5 ( η -C 3 t Bu 3 P 2 )] 1 are described. The lone pair electrons of the two adjacent phosphorus atoms of the C 2 t Bu 2 P 3 ring in the triphospha-ferrocene complex [Fe( η 5 -C 5 Me 5 )( η 5 -C 2 t Bu 2 P 3 )] 2 can ligate to other metal centres. The results of single crystal X-ray structural studies of the molybdenum and tungsten pentacarbonyl η 1 -complexes [Fe( η 5 -C 5 Me 5 )( η 5 -C 2 t Bu 2 P 3 )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 [(C 5 H 4 Me)(CO) 2 Mn(THF)] to form the adduct [Fe( η 5 -C 5 Me 5 )( η 5 -C 2 t Bu 2 P 3 )Mn(CO) 2 ( η 5 -C 5H H 4 Me) ] 6 . The phenyl-substituted di- and triphosphacyclopentadienides [Na(DME) 3 ][C 3 Ph 3 P 2 ] and [Na(DME) 3 ][C 2 Ph 2 P 3 ] (DME = 1,2-dimethoxyethane) react with ferrous chloride and Li[C 5 Me 5 ] to give the ‘sandwich’ compounds [Fe( η 5 -C 5 Me 5 )( η 5 -C 3 Ph 3 P 2 )] 9 and [Fe( η 5 -C 5 -C 5 Me 5 ( η 5 -C 2 Ph 2 P 3 )] 10 . The The latter reacts with W(CO) 5 (THF) to yield the η 1 -complex [Fe( η 5 - C 5 Me 5 )( η 5 -C 2 Ph 2 P 3 )W(CO) 5 ] 11 .

While the secondary phosphines (1-Ad) 2 PH (1) (l-Ad = adamantyl) and Trt(Ph)PH (2) (Trt = triphenylmethyl) reacted readily with trifluoroacetic anhydride (TFAA) to give the trifluoroacetylphosphines 7 and 8 . (1-Ad) 2 P(:O)H (6) could not be converted into the corresponding trifluoroacetylphosphine oxide 10 by treatment with TFAA. Compound 10 was observed by 19 F and 31 P NMR spectroscopy in the reaction of (1-Ad) 2 PC(:O)CF 3 (7) with (H 2 N) 2 C(:O) · H 2 O 2 . Two pathways were observed for the reaction of 1 with excess hexa-fluoroacetone (HFA), starting from the primary HFA adduct (1-Ad) 2 PC(CF 3 ) 2 OH (13) . Oxidation of 13 led to the tertiary phosphine oxide 14 which was also available from (1-Ad) 2 P(:O)H (6) and HFA. Isomerization of 13 gave (1-Ad) 2 POCH(CF 3 ) 2 (15) whose oxidation with excess HFA furnished the phosphorane 16 . Hydrolysis of 16 led to the phosphinic ester 17 . As is known for Ph 2 PH (3) , Ph(C 6 F 5 )PH (4) reacted with HFA to give the α-hydroxyphosphine 19 . No reaction was observed when Trt(Ph)PH (2) and (C 6 F 5 ) 2 PH (5) were treated with HFA.

5,6-Benzo-1,3-dimethyl-2 H -2-oxo-1,3,2λ 4 -diazaphosphorinan-4-one (1) and 1,3,5-trimethyl-2 H -2-oxo-1,3,5-triaza-2λ 4 -phosphorinan-4,6-dione (2) were allowed to react with perfluoro-isobutylmethyl ketone (4), perfluoro-1-methyl-2-isopropyl diketone (5) and perfluoro-1-methyl-2-n-propyl diketone (6), leading to the products 7-12 by formation of a P-O-C bond and migration of the hydrogen atom from phosphorus to the carbonyl carbon atom as a result of an O-addition reaction. In the reaction of 2 with 6, the formation of two isomers 12a and 12b was observed. Reaction of a mixture of 12a and 12b with water led to 2-hydroxy-2-oxo-triazaphosphorinan-4,6-dione (15) and two further perfluorinated products 13 and 14. Dimethylphosphine oxide (3) reacted with perfluoro-isobutylmethyl ketone (4) to give the perfluoroalkyl-substituted α-hydroxyphosphine oxide 16. In contrast to 7-12, compound 16 was shown to contain the P-C-OH fragment rather than a P-O-C bond. The existence of 7-9 in diastereomeric pairs and of 16 as an enantiomeric pair has been established by 1 H, 13 C and 19 F NMR spectroscopy. All compounds were characterized by NMR spectroscopy, mass spectrometry and elemental analysis. X-Ray crystal structure analyses have been carried out for the substituted diaza- and triaza-phosphorinanones 9 and 11. Compound 9 crystallizes as two independent molecules, which are, however, closely similar. Hydrogen bonds of the form C-H····O are observed for 9 and (weakly) in 11; the fluorine substituents presumably make the chain H atoms more positive.

Whereas no reaction occurred when the organophosphonous acids RP(:O)(H)OH (R = Ph, Ph 3 C) were treated with hexafluoroacetone trihydrate, the addition of excess pyridine to the reaction mixture led, with evolution of heat, to the formation of adducts of the type [C 5 H 5 NH] + [RP(:O)(H)O) − 2 ·3F 3 CC(OH) 2 CF 3 [R = Ph (1), CPh 3 (2)]. The structure of 1 has been determined by X-ray analysis; it consists of bands of hydrogen-bonded residues.

The reactions of the 5,6-benzo-2-chloro-1,3-dimethyl- or 1-methyl-3-(2-chloroethyl)-1,3,2λ 3 -diazaphosphorinan-4-ones 1 and 2 with the triethylamine · 3HF adduct in a molar ratio 3:1 in the presence of excess triethylamine furnished the 2-fluorosubstituted 1,3,2λ 3 -diazaphosphorinanones 3 and 4 in good yield. In the reactions of 1 and 2 with trimethylsilylmethyl ether or methanol in the presence of free triethylamine, the 2-methoxy-substituted-1,3,2λ 3 -benzodiazaphosphorinan-4-ones 5 and 6 were formed. Oxidation of 3 and 4 to the 2-fluoro-2-oxo-1,3,2λ 4 -benzodiazaphosphorinanones 7 and 8 was effected either by aqueous hydrogen peroxide or by the hydrogen peroxide-urea 1:1 adduct. Furthermore, substitution of the 2-chloro-2-oxo-1,3,2λ 4 -benzodiazaphosphorinanones 9 and 10 with the triethylamine·3HF adduct in a molar ratio of 3:1 in the presence of excess triethylamine furnished the corresponding derivatives 7 and 8, involving λ 4 -phosphorus. The phosphoryl chloride derivatives 9 and 10 were obtained in the reaction of the 2-P-methoxy derivatives 5 and 6 with sulfuryl chloride. Compounds 9 and 10 were allowed to react with the amine derivatives, 2-chloroethylamine hydrochloride and bis(2-chloroethyl)amine hydrochloride, in the presence of triethylamine in a molar ratio of 1:2, forming the λ 4 -phosphorus derivatives 11-13. Characterization of 3-13 was based on their NMR spectra and mass spectra. X-Ray structure determinations of 7 and 8 are described. In both structures the phosphorus atom has a distorted tetrahedral coordination geometry. The six-membered heterocycle of 7 displays an envelope conformation with the phosphorus atom out of plane, whereas the heterocycle of 8 displays a distorted envelope conformation with the phosphorus atom and one nitrogen atom out of plane.

5,6-Benzo-1-methyl-3-(2-chloroethyl)-2-hydro-2-oxo-1,3,2 λ 4 -diazaphosphorinan-4-one ( 2 ) reacts with p -benzoquinone in a 1:1 molar ratio in the presence of triethylamine as a catalyst to give as the sole addition product 5,6-benzo-1-methyl-3-(2-chloroethyl)-2-(2,5-dihydroxyphenyl)-2-oxo-1,3,2 λ 4 -diazaphosphorinan-4-one ( 3 ). No reaction occurred betwwen 2 and acetone, methyl t-butylketone or acetophenone in the presence of triethylamine, even at elevated temperature. The reaction of the 5,6-benzo-1,3-diorgano-2-hydro-2-oxo-1,3,2 λ 4 -diazaphosphorinan-4-ones 1 and 2 with hexafluoroacetone furnished the 2-hexafluoroisoproposy-substituted compounds 4a and 5a . In both cases, the 2-bis(trifluoromethyl)hydroxymethyl-substituted structural isomers 4b and 5b were formed in low yield. Analogous reactions of 1 and 2 with trifluoroacetophenone, catalysed by triethylamine, furnished as the main products the 2-trifluoromethylphenylmethoxy-substituted compounds 6a and 7a , together with small amounts of the 2-trifluoromethylphenylhydroxymethyl-substituted isomers 6b and 7b . The unusual reaction of the acetylaminophosphorinanone 8 with hexafluoroacetone in a 1:2 molar ratio led to the formation of the 2-hexafluoroisopropoxy-substituted compound 4a with N-acetyl-bis(trifluoromethyl)imine ( 11 ) as a by-product. A pathway for the formation of 4a is proposed. Characterization of 3 and 4a–7a was based on 1 H, 13 C, 19 F and 31 P NMR and mass spectra. The existence of 4a, 5a, 4b and 5b as enantiomeric pairs was established mainly by 19 F NMR spectroscopy. The diasteromeric pairs 6a and 7a, 6b and 7b were not observed in the 19 F and 31 P NMR spectra. X-ray structure analyses were carried out for 4a, 5b and 7a . Compound 7a crystallizes with two independent molecules, which are however closely similar. Intermolecular hydrogen bonds of the form P(:O)…H are observed for all compounds, leading to centrosymmetrical dimers. In 4a the two trifluoromethyl substituents presumably make the carbon H atom more positive. The existence of hydrogen bonds is confirmed by infrared spectroscopic studies. In all structures the phosphorus atom exhibits a distorted tetrahedral coordination. The six-membered heterocycle of 4a displays an envelope conformation with the phosphorus atom out of plane.

N,N′-Disubstituted derivatives of 5,6-benzo-2H-2-oxo-1,3,2-diazaphosphorinan-4-one (2–6), 1,3,5-trimethyl-2H-2-oxo-1,3,5-triaza-2λ4-phosphorinan-4,6-dione (12), phenylphosphinic acid (14) and dimethylphosphine oxide (16) have been added across the CN double bond of phenyltrifluoromethylketimine (1) in the presence of catalytic quantities of triethylamine, leading to the formation of N,N′-disubstituted derivatives of 5,6-benzo-2-(1-amino-1-phenyl-2,2,2-trifluoroethyl)-2-oxo-1,3,2-diazaphosphorinan-4-one (7–11), 2-(1-amino-1-phenyl-2,2,2-trifluoroethyl)-1,3,5-trimethyl-2-oxo-1,3,5-triaza-2λ4-phosphorinan-4,6-dione (13), phenyl-(1-amino-1-phenyl-2,2,2-trifluoroethyl)phosphinic acid (15) and dimethyl-(1-amino-1-phenyl-2,2,2-trifluoroethyl) phosphine oxide (17), respectively. Addition of N,N′-disubstituted derivatives of 5,6-benzo-2H-2-oxo-1,3,2-diazaphosphorinan-4-one (2–4) and (21) and of 1,3,5-trimethyl-2H-2-oxo-1,3,5-triaza-2λ4-phosphorinan-4,6-dione (12) across the CN double bond of bis(trifluoromethyl)ketimine (20) resulted in N,N′-disubstituted derivatives of 5,6-benzo-2-(1-amino-1-trifluoromethyl-2,2,2-trifluoroethyl)-2-oxo-1,3,2-diphosphorinan-4-one (22–25) and 2-(1-amino-1-trifluoromethyl-2,2,2-trifluoroethyl)-1,3,5-trimethyl-2-oxo-1,3,5-triaza-2λ4-phosphorinan-4,6-dione (26), respectively. The compounds were characterised by 1H, 13C, 19F and 31P NMR spectroscopy, mass spectrometry, elemental analysis and a single-crystal X-ray structure analysis in the case of compound 22. The heterocycle displays an envelope conformation. The structure shows one intermolecular hydrogen bond, leading to the formation of centrosymmetric dimers.

The reactions of chlorophosphines 1 with (S)- or (R)-1-methylbenzylamines 2 proceed stereoselectively to give N-(1-methylbenzyl)aminophosphines 3, which were isolated as crystalline borane complexes with 100% diastereomeric purity. The absolute configuration of the new chiral compounds was established by X-ray analysis and chemical extrapolation.

This review is concerned with the role of the N , N ′, N ′-trimethylethylenediamine group as a substituent at phosphorus atoms in different coordination and/or oxidation numbers. A few examples for silicon are also presented. Intramolecular donor-acceptor interactions between the nitrogen atom of the dimethylamino group and Si or P as the central atom were first noted in some N , N ′, N ′-trimethylethylenediamine-substituted fluorosilanes (LSiF 3 , PhSiF 2 L) and P(III)Cl systems, e.g. LPCl 2 and PhP(Cl)L (L = N , N ′, N ′-trimethylethylenediamine group). These observations gave rise to a more detailed study of the coordinating behavior, especially of further phosphorus compounds of different substitution pattern. Spontaneous intramolecular coordination with formation of salt-like products was observed, especially, for compounds in which a phosphorus-bonded halogen atom is available to dissociate as an anion. A dependence both on the nature of the halogen atom and on the nature of other ligands at P(III) [or P(V)] was noted and will be discussed. Through the action of Lewis acids, e.g. AlCl 3 of PF 5 , or in the reaction with tetraphenylborate as a non-coordinating anion, halide abstraction and consequent formation of the Me 2 N → P coordinative bond from cyclic N , N ′, N ′-trimethylethylenediamine-substituted halophosphines or trimethylethylenediamine-substituted fluorophosphoranes could be induced. No such Me 2 N → P coordination took place during oxidation of N , N ′, N ′-trimethylethylenediamine-substituted phosphorus(III) compounds with oxidizing agents, e.g. sulfur, selenium, o -quinones or hexafluoroacetone. Numerous oxidation reactions were conducted on intramolecularly stabilized phospholidin-1-ium salts. They furnished the expected oxidation/addition products. This was accompanied in some cases (depending on the nature of the substituents at P(III)) by a scission of the coordinative Me 2 N → P bond. The reaction of phospholidin-1-ium salts with phenyl azide, dimethyl sulfoxide and sulfur furnished phosphonic acid diamides and substituted λ 4 -phospholidin-1-ium salts, as well as substituted diazadiphosphetidines, as a result of the dimerization of PN species. Intramolecular donor-acceptor interaction in N , N ′, N ′-trimethylethylenediamine-substituted fluorophosphoranes was only observed in the presence of the Lewis acid, phosphorus pentafluoride leading to the formation of hexafluorophosphate salts. The reaction of dialkylamino-substituted tetrafluorophosphoranes with N , N ′, N ′-trimethylethylenediamine took an unusual course. Instead of the expected PF cleavage and formation of an N , N ′, N ′-trimethylethylenediamine-substituted dialkylaminotrifluorophosphorane, cyclic tetrafluorophosphates with a λ 6 P atom, and dialkylaminotrimethylsilane were formed. The reaction of phosphorus(III)- N , N ′, N ′-trimethylethylenediamine compounds with transition metal compounds [Fe(0), Cr(0), Mo(0), Pt(II)] furnished mono-, di- or trisubstituted coordination compounds, depending on the nature of the metal. The P(III) ligand was bonded in some cases via P(III) only (as a monodentate ligand) and in other cases as a chelating ligand coordinated via P(III) and N. A variety of variable-temperature NMR experiments have examined the dynamic processes occurring at room temperature in solution, and X-ray single-crystal structure determinations have been conducted in many cases to characterize these new and unusual compounds.

The spirocyclic N , N ', N '-trimethylethylenediamine-substituted phosphorane 2 was formed in the reaction of 2-[2-( N , N -dimethylamino)ethylmethylamino]-1,35-trimthy-1,3,5- triaza-2λ 3 -phosphorinane-4,6-dione ( 1 ) with hexa-fluoroacetone. Surprisingly, both thermolysis in vacuo and hydrolysis of 2 led to the phosphoryl compound 3 . Compound 3 was also formed in the reaction of 1 with aqueous H 2 O 2 or with the hydrogen peroxide/urea 1:1 adduct. Compound 3 crystallizes with one molecule of H 2 O 2 per formula unit (→ 3a ). The single crystal X-ray analysis of 3a shows an extended 2-[2-( N , N -dimethylamino)ethylmethylamino] substituent with a short P-N bond. Hydrogen peroxide is involved in hydrogen bonds of the type P=O⋯H and Me 2 N⋯H. The reaction of 5,6-benzo-1,3-dimethyl-2-[2-( N , N -dimethylamino)ethylmethylamino]-1,3,2-diazaphosphorinane-4-one ( 4 ), related to 1 , with H 2 O 2 furnished an oily product, 5,6-benzo-1,3-dimethyl-2-[2-( N , N -dimethylamino)ethylmethylamino]-2-oxo-1,3,2-diazaphosphorinane-4-one ( 5 ) which could not be crystallized, and which (according to IR spectroscopic evidence) did not display intermolecular interactions in a similar manner to 3a .

The reactions of the 1,3-dimethyl-1,3-diaza-2-P-substituted-(2-chloroethyl)- or bis(2-chloroethyl)amino-2λ 3 -phosphorinan-4-ones 1 and 4 with hexafluoroacetone in a molar ratio of 1:2 furnished the spirophosphoranes 2 and 5 . In the reaction of 1 with hexafluoroacetone, small amounts of the by-product 3 , involving λ 4 phosphorus were formed and characterized by 19 F and 31 P NMR spectroscopy. The 1,3-dimethyl-1,3-diaza-2-oxo-5,6-benzo-2λ 4 -phosphorinan-4-ones 6 and 7 were obtained from the spirophosphoranes 2 and 5 , either by reaction with water or on heating; in the latter case, the elimination of tetrakis(trifluoromethyl)oxirane is suggested as occurring. Characterization of 2 and 5–7 was on the basis of their 1 H-, 13 C-, 19 F- and 31 P-NMR spectra, and their mass spectra.

The λ3P,λ5P-fluorophosphorane (1) involves a λ3 phosphorus atom directly linked to a λ5P phosphorus atom. It is therefore of interest whether the coordinating ability of the λ3 phosphorus atom in1 is affected by the directly bonded λ5 phosphorus atom. A number of complexes of1 were prepared with rhodium(I), iridium(I), and platinum(II).1 Was found to display normal ligand behaviour. Compounds were characterized especially by NMR-spectroscopy (1H,19F,31P) and, in the case of the complex (nBu3P)·(1)·PtCl2,8b, by a single-crystal X-ray diffraction study. The P P bond length is 226.6 pm, compared to 226.7 pm in the free ligand. Slight distortions from square planar coordination of platinum are observed.

The reaction of (E)-bis(2,4,6-tri-tert-butylphenyl)diphosphene with Ru-3(CO)(12) results in cleavage of the P=P bond with concomitant C-H activation of one of the t-butyl groups to form Ru-3(mu-H)(2)(CO)(8)(mu-P-C6H2-2,4-Bu-t(2)-6-CMe2CH2)(2). The H-atoms have transferred from the ligand to the metal core. (C) 2002 Elsevier Science B.V. All rights reserved.

The reactions between (1-Ad)nPH3-n (1-Ad = 1-adamantyl; n = 1,2) and M(CO)6 (M = cr; Mo, W), Fe2(CO)9 and Ni(CO)4 led to mononuclear derivatives of the type (OC)mM[(1-Ad)nPH3-n] (m = 5, M = Cr, Mo, W; m = 4, M = Fe; m = 3, M = Ni; n = 1, 2). Although rather unreactive, as a result of the 1-adamantyl substitution, some of these compounds were employed for further synthesis under more vigorous conditions. Thus, pyrolysis of (1-AdPH2)Fe(CO)4 (7) furnished the binuclear cluster (1-AdPH)2Fe2(CO)6 (11), whereas substitution of a PH proton in the chromium complex (1-AdPH2)Cr(CO)5 (1) by a diisopropylphosphino group led to the diphosphine complex (OC)5Cr(1-AdPHPiPr2) (15), which isomerized at elevated temperatures to (1-AdPHPiPr2)Cr(CO)5 (15a) with liberation of the diphosphine 1-AdPHPiPr2 (16). The crystal structure of 15 is described; the PP bond length is 223.6(1) pm. 1-AdPH2 reacted with Fe3(CO)12 with the formation of a mixture of bi- and trinuclear iron carbonyl clusters.

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.

Addition of [Et4N]F to Me2SnF2 suspended in CH2Cl2 or CH3CN caused the formation of the organofluorostannate [Et4N][Me4Sn2F5]− which was isolated in pure, crystalline form. The X-ray crystal structure analysis of this compound provides the first example of a linear, fluorine-bridged polyfluorostannate. The structure involves two types of tin (both with octahedral coordination), three types of fluorine atoms (two bridging, one terminal, all equatorial) and two types of methyl groups (both axial). The structure can be formally derived from a so far unknown linear polymeric [Me2SnF3]− anion with four equatorial fluorines (two bridging, two terminal), by bridging of the terminal fluorines of neighbouring monomers via additional Me2SnF2 molecules. Even at low temperatures no NMR spectroscopic signals involving fluorine couplings could be observed, which indicates a rapid exchange of fluorine atoms.

In the reaction of bis(trimethylsilyl)carbodiimide ( 1 ) with excess PF 2 Cl only the monosubstituted carbodiimide 2a was obtained. The carbodiimide structure is suggested by 15 N and 29 Si NMR spectra. Two equivalents of 2a were found to react with (COD)PtCl 2 ( 3 ) (COD = 1,5-cyclooctadiene) with the displacement of COD and the formation of 4 , which underwent rapid loss of trimethylchlorosilane forming the trimer 5 and the polymer 6 , which was an insulator. When 6 was doped with SbF 5 , TTF (tetrathiafulvalene), [(C 4 H 9 ) 4 N] + [BF 4 ] − , [NO] + [BF 4 ] − or [(C 4 H 9 ) 4 N] + [PF 6 ] − , its electrical conductivity increased by about 13 orders of magnitude.

The reaction of the N-trimethylsilyl-substituted heterocycles, trimethylsilyl- pyrazole. 1,-imidazole, 3,-5,6-dimethylbenzimidazole, 7, and 1,3,4-triazole, 8 with phosphorus pentafluoride was studied. The reaction proceeded via the initial formation of 1:1 Lewis acid-base adducts between phosphorus pentafluoride and the nitrogen atom bearing the Me3Si group. In the reaction of 1 with PF5 the unusual bis-tetrafluorophosphate complex. 2 was directly formed by cleavage of Si-N bonds and elimination of Me3SiF. The reaction of the trimethylsilylated triazole. 8 with PF5 produced a mixture of substances. The dimer 5 was formed during thermolysis of 4. The products were characterized by 1H, 13C, 19F, and 31p n.m.r spectroscopy. A single crystal X-ray structure determination was conducted for the pyrazole- bridged bis-tetrafluorophosphate complex. 2, in which the central six- membered ring (P2N4) adopts a boat conformation.

2-Dimethylaminomethyl-6-methoxyphenyldifluorophosphine, 1 was prepared from 2-dimethylaminomethyl-6-methoxyphenyllithium and PF 2 Cl. The 19 F and 13 P NMR parameters of 1 showed significant differences from those of other aryldifluorophosphines, and it is suggested that an intramolecular donor-acceptor interaction exists between the nitrogen atom of the NMe 2 group and the trivalent phosphorus atom. Strong non-bonding PN-interactions have also been observed for a coordination compound of 1 with platinum(II), [2-Me 2 NCH 2 -6-MeOC 6 H 3 PF 2 ] 2 PtCl 2 , 7 , for which a single crystal X-ray diffraction study is reported.

The reaction of λ 3 -phospha-diazetidin-thione, 1 with hexafluoroacetone (HFA) furnished not only the expected addition product, the λ 5 P-perfluoropinacolyl phosphorane, 2 . In addition, HFA was observed to cause exchange in 2 , and exclusive formation of a urea derivative, 3 , was noted upon prolonged interaction of HFA with 2 . Likewise, N,N,N′,N′,-tetramethylthiourea, 1 , was found to be converted to N,N,N′,N′-tetrarmethylurea, 5 , by HFA. The reactions were followed by 1 H−, 13 C−, 19 F− and 31 P-n.m.r. spectroscopy.

Bis[2,4-bis(trifluoromethyl)phenyl]fluorophosphine, 1 , and 2,4-bis(trifluoromethyl)phenyl-[2,6-bis(trifluoromethyl)phenyl]fluorophosphine, 2 , were found amongst the products of the reaction of 1,3-bis(trifluoromethyl)benzene with n-butyllithium, followed by chlorodifluorophosphine. The mixture of 1 and 2 was a stable, distillable oily liquid, which crystallized on standing. The reaction of the mixture of 1 and 2 with dichloro-(η4-1.5-cyclooctadiene)platinum(II) led to the formation of cis-dichloro-bis(bis(2,4-bis(trifluoromethyl)phenyl)fluorophosphino)platinum(II), 3 . The products 1 , 2 and 3 were characterized by their 1H-.19F- and 31P-NMR and mass spectra. The long-range coupling constants 4J(PF) and 5J(FF) are discussed. The structure of 3 was confirmed by a single crystal X-ray investigation. 3 crystallizes in the monoclinic space group C 2/ c with cell constants a = 1331.8(3). b = 2392.5(4), c = 1263.1(2) pm, β = 93.75(2)° and Z = 4 (the complex possesses crystallographic twofold symmetry). The bond lengths Pt-P 221.7, Pt-Cl 232.6, P-F 155.9 pm all lie in the expected range for platinum fluorophosphine complexes.

The 1H NMR spectrum of the spirophosphorane 1 at room temperature indicates dynamic behaviour of the cation. From high and low temperature 1H NMR spectra it is concluded that exchange between the N(CH3)2 groups and between the NCH3 groups in the four-membered ring takes place. The free enthalpy of activation for this dynamic process was determined (62.4±2.5 kJ mol−1). In the reaction of 1 with sodium tetraphenylborate the crystalline compound, 2, involving the non-coordinating anion, [B(C6H5)4]−, was obtained. The X-ray crystal structure analysis of 2 reveals the presence of a five-membered ring, formally as a result of intramolecular donor-acceptor interaction between the nitrogen atom of the N(CH3)2 group and phosphorus.

The diphosphorus compounds R1R2PPR1R2 (R1 = R2 = Me or Et; R1 = Me, R2 = But) and Me2P(:O)PMe2 were found to react with hexafluoroacetone (HFA) to give 1,2-λ5-oxaphosphetanes, phosphonates and phosphinates. For R1 = R2 = Et and R1 = Me, R2 = But 1,3,2,-λ5-dioxaphospholanes were obtained. For R1 = R2 = Et, in addition, a 1,3,4-λ5-dioxaphospholane was found. With tetramethyldiphosphine a thermally stable compound was formed containing a P(III)C(CF3)2OP(V) moiety which could be bound to a (OC)4Mo fragment. No reaction has been observed between HFA and But2PPBut2 and Ph2PPPh2.

A series of phosphoranes containing the hexafluoroisopropoxy group has been synthesized and characterized by 1 H, 19 F, and 31 P n.m.r., and by mass spectrometry. Some variable temperature n.m.r. studies are reported and the results are discussed in terms of possible ground state structures of the phosphoranes.

The cyclic trifluorophosphoranes, (CH2)nPF3(n = 4, 5; 1c and 1d) were found to react with 8-trimethylsiloxyquinoline (2) with cleavage of the SiO bond and formation of the mono-substituted derivatives, (CH2)nPF2(Ox), 4 and 5 (Ox = 8-oxyquinolyl). In the case of 4, intramolecular coordination between the nitrogen atom of the quinolyl group and phosphorus rendering phosphorus hexa-coordinate (λ6P) has been established by NMR spectroscopy (31P, 19F). By contrast, this type of interaction between N and P is not observed in the case of 5 which is, therefore, a normal substituted fluorophosphorane with λ5P. Intramolecular coordination, involving λ6P, is observed, however, in the case of the products originating from the reaction of the trimethylsilyl ester of N,N-dimethylglycine, Me2NCH2C(:O)OSiMe3 (6) with both PF5 and PhPF4; it has been indicated for both 7 and 8 by NMR spectroscopy. In the case of 8, a single crystal X-ray structure determination has confirmed the intramolecular coordination between P and N, with the formation of hexa-coordinate phosphorus.

With several chloro ruthenium phosphine complexes, allyldifluorophosphite, F2POC3H5, displaces triphenylphosphine to form new compounds in which it acts as a phosphorus donor ligand. The new complexes [PPh3]2[F2POC3H5]Ru[CO][Cl][H], I, and [(PPh3)2(F2POC3H5)2RuCl2]n II, hav characterized by chemical, spectroscopic, and, in the case of I, crystallographic means. This behaviour of F2POC3H5 contrasts to its reactions with several platinum and palladium chloro complexes where it undergoes Arbuzov-type rearrangements.

Durch Umsetzung von N,N′-Dimethyl-N,N′-bis(trimethylsilyl)harnstoff mit MePCl2 ist das Chlor-substituierte Diphosphin 1 zuganglich. 1 reagiert mit uberschussigem Hexafluoraceton unter Abspaltung von MePCl2 zum Spirophosphoran 3, dessen Struktur durch Rontgen-Struktur-analyse bestimmt wurde. Am Phosphor liegt annahernd trigonal-bipyramidale Geometrie vor. – Durch Umsetzung von 1 mit Tetrachlor-o-benzochinon (TOB) wird ein zu 3 analoges Phosphoran 4 erhalten. Enthalogenierung von 1 liefert das Diphosphin 7, das mit einem Aquivalent TOB quantitativ zur λ3P – λ5P-Diphosphorverbindung 10 umgesetzt werden kann. Der Versuch, 10 am λ3-Phosphor mit TOB weiter zu oxidieren, fuhrt zur Spaltung der P–P-Bindung unter Bildung von 4 und eines weiteren Spirophosphorans 9, das formal durch oxidative Addition von zwei Aquivalenten TOB an eine PMe-Einheit entsteht. 4 und 9 werden auch bei der Umsetzung von 7 mit mehr als einem Aquivalent TOB erhalten. Reaktion von 1 mit Me2NSiMe3 liefert quantitativ die Diphosphorverbindung 11, die je ein λ3- und λ4-Phosphoratom in direkter Bindung enthalt. N,N′-Dimethylurea-bridged Diphosphorus Compounds; Structure of a Spirophosphorane with λ5-Phosphorus as a Bridging Atom Reaction of N,N′-dimethyl-N,N′-bis(trimethylsilyl)urea with MePCl2 yields the chloro-substituted diphosphine 1. With excess hexafluoroacetone 1 reacts with loss of one equivalent of MePCl2 and formation of the spirophosphorane 3 whose structure has been determined by X-ray diffraction. The geometry at phosphorus is approximately trigonal-bipyramidal. A spirophosphorane analogous to 3 is obtained by reaction of 1 with tetrachloro-o-benzoquinone (TOB). Dehalogenation of 1 furnishes the diphosphine 7 which reacts quantitatively with one equivalent of TOB to give the λ3–λ5P-diphosphorus compound 10. Attempted further oxidation of 10 with TOB at the λ3P atom leads to cleavage of the P–P bond with formation of 4 and a further spirophosphorane 9 which results, formally, from the oxidative addition of two equivalents of TOB to a PMe unit. Formation of 4 and 9 is also observed upon reaction of 7 with more than one equivalent of TOB. In the reaction of 1 with Me2NSiMe3 the P–P-bonded compound 11 is obtained, containing one λ3-and one λ4-phosphorus atom directly bonded.

The preparation of the ortho-substituted aryldifluorophosphines 2-MeOC6H4PF2 and 2-Me2NC6H4PF2 by chlorine-fluorine exchange from the corresponding dichlorophosphines using sodium fluoride in acetonitrile in the presence of a crown ether is described. The ortho-substituted aryldichlorophosphines 2-MeOC6H4PCl2 and 2-Me2NC6H4PCl2 were prepared from the respective bis(N,N-dimethylamino) phosphines by cleavage of the PN bonds with hydrogen chloride. The reaction of 4-fluoroanisole and 2-methoxy-phenyllithium with phosphorus trichloride did not yield the expected chlorophosphines, i.e. 2-MeO-5-F-C6H3PCl2 and 2-MeOC6H4PCl2, but led to formation of 4-fluorophenyldichlorophosphite in the former, and to tris(2-methoxyphenyl)phosphine in the latter case. The difluorophosphine 2-MeOC6H4PF2 was found to undergo a spontaneous oxidation-reduction reaction with formation of the tetrafluorophosphorane 2-MeOC6H4PF4, and the cyclotetraphosphine (2-MeOC6H4P)4. A single-crystal X-ray structure determination of the latter indicated the presence of a strongly puckered four-membered ring with PP bond lengths ranging between 222 and 223 pm, and endocyclic bond angles of 84°. Vicinal MeOC6H4 groups were found arranged trans to each other. Dichloroplatinum(II) complexes were prepared, involving the two new fluorophosphines, 2-XC6H4PF2 (X = MeO or Me2N), as ligands. In neither case was any evidence found for coordination between platinum and oxygen or nitrogen, and the fluorophosphines were found to function solely as phosphorus donors. The absence of interaction between platinum and the oxygen atom in the ortho position of the ligand 2-MeOC6H4PF2 was confirmed in a single-crystal X-ray determination of the complex Cl2(2-MeOC6H4PF2)2Pt. The compound was found to exist as a planar, cis-coordinated species with PtCl bond lengths between 232 and 234 pm, and a PtP bond length of 218 pm. All compounds were characterized by NMR spectroscopy (1H, 31P and 19F, where applicable).