Ph2P CH2CH2P Research Articles

Reactions of a novel quadruply chelated molybdenum–silyl complex with β-dicarbonyl compounds

The novel molybdenum–silyl complex [MoH 3{[Ph 2PCH 2CH 2P(Ph)–C 6H 4- o] 2(Ar)Si -P,P,P,P, Si}] ( 1) reacted with 2,4-pentanedione to give eight-coordinate dihydrido complex 2 ( a, Ar=Ph; b, Ar= o-tolyl) with a chelated 2,4-pentanedionato ligand as a result of repelling one of four Mo–P bonds in 1. On the other hand, the reaction between 1 and dialkyl malonates gave an η 1- O-enolato type complex in which the quadruply chelated P–P–Si–P–P framework was found to be kept intact. The structure of 2a was confirmed by X-ray crystallographic structure analysis.

Quadruply bonded complexes containing η2- or η3-tridentate phosphine ligands; syntheses, structures and 31P{ 1H} NMR spectra of Mo 2Cl 4( η3-etp)(L) and Mo 2Cl 4( η2-etp) 2 (L = CH 3OH, PMe 3 and PEt 3; etp = Ph 2PCH 2CH 2P(Ph)CH 2CH 2PPh 2)

The reactive complex Mo 2Cl 4( η 3-etp)(CH 3OH) (etp = Ph 2PCH 2CH 2P(Ph)CH 2CH 2PPh 2) ( 1) was synthesized by reacting (NH 4) 5Mo 2Cl 9 with 1 equiv. of etp in CH 3OH. Reactions of 1 with PMe 3 and PEt 3 in THF gave Mo 2Cl 4( η 3-etp)(PMe 3) ( 2) and Mo 2Cl 4( η 3-etp)(PEt 3) ( 3) respectively. The complex α-Mo 2Cl 4( η 2-etp) 2 ( 4) was synthesized by refluxing Mo 2Cl 4( η 3-etp)(CH 3OH) with 1 equiv. of etp in CH 3OH, where η 3-etp is transformed to η 2-etp. Complex 4 can also be prepared by reacting (NH 4) 5Mo 2Cl 9 with 2 equiv. of etp in refluxing CH 3OH. Their UV-Vis and 31P NMR spectra were recorded and the structures of 3 and 4 were determined. Crystal data for 3·C 7H 8: space group P2 1/n, a = 11.846(2), b = 29.349(3), c = 15.429(3) A ̊ , β = 112.52(1)°, V = 4955(2) A ̊ 3, Z = 4 , with final residuals R = 0.0797 and R w = 0.0811. Crystal data for 4·2C 7H 8: space group P2 1/c, a = 14.555(2), b = 14.988(2), c = 20.220(3) A ̊ , β = 106.80(1)°, V = 4222(1) A ̊ 3, Z = 2 , with final residuals R = 0.0882 and R w = 0.0893. The etp ligands in 1–3 are coordinated to the Mo centers in tridentate fashion with chelating/bridging bonding modes. The etp ligands in 4 are chelated to the Mo centers in bidentate fashion through the central phosphorus atom and one terminal phosphorus atom. Complex 4 appears to be the first binuclear biligate complex chelated by linear tridentate ligands. Study of the 31P{ 1H} NMR spectrum of 3 leads to the conclusion that the through metal-metal quadruple bonding coupling | 4 J PMoMoP| is in the range from 18.18 to 24.28 Hz for complexes of the type Mo 2Cl 4( η 3-etp)(L) (L = monodentate ligand).

Some rhenium hydride complexes with tetradentate phosphine co-ligands: the crystal structure of Re(H 2BEt 2)( racemic-tetraphos)

ReH 5(PMePh 2) 3 reacts with P(CH 2CH 2PPh 2) 3 (PP 3) in the absence of solvent at 180° to give ReH(PMePh 2)(PP 3). Under similar conditions, ReCl 3(PMePh 2) 3 reacts with tetraphosphine ligands PP 3 or commercially available P 4 (Ph 2PCH 2CH 2P(Ph)CH 2CH 2P(Ph)CH 2CH 2PPh 2) to produce ReCl 3(PP 3) and ReCl 3(P 4), respectively. Treatment of ReCl 3(PP 3) with NaBH 4 yielded ReH 3(PP 3), which is converted into [ReH 4(PP 3)] + when protonated. Treatment of ReCl 3(P 4) with NaBH 4 in MeOH/benzene produced a mixture of ReH 3( meso-P 4) and ReH 3( rac-P 4). On the other hand, a mixture of ReH 3( meso-P 4) and the novel complex Re(BH 2Et 2)( rac-P 4) was obtained when ReCl 3(P 4) was treated with an old sample of LiBHEt 3 (actually containing LiBEt 4/LiBH 2Et 2) in THF. Protonation of ReH 3( meso-P 4) produced [ReH 4( meso-P 4)] +. The T 1 values of the hydride resonances of the hydride complexes suggested that all are classical rhenium hydride complexes as the Re centres are too basic to form η 2-dihydrogen complexes. Re(H 2BEt 2)( rac-P 4) crystallized in the space group C2/ c with cell parameters a = 17.651(3), b = 13.874(2), c = 17.694(4) Å, β = 102.22(2)°, V = 4235(3) Å 3, Z = 4 R = 0.028 and R w = 0.029 for the 3343 reflections with I > 3σ( I). The BH 2Et 2 − unit is bound to rhenium via the two bridging hydrides.

Multinuclear ( 31P, 195Pt) magnetic resonance and electrospray mass spectrometric studies of the reactions between platinum bis(dithiolates) and two potentially tetradentate phosphine ligands

The reactions of platinum(II) bis(dithiolates) Pt(SS) 2 ((SS)=S 2P(OEt) 2 (dtp), S 2CO nPr (xan), S 2CNEt 2 (dtc)) with two potentially tetradentate phosphine ligands have been investigated by multinuclear magnetic resonance spectroscopy and electrospray mass spectrometry (ESMS). The phosphines used were P(CH 2CH 2PPh 2) 3 (P 3P′) and Ph 2PCH 2CH 2P(Ph)CH 2CH 2P(Ph)CH 2CH 2PPh 2 (P 2P′ 2). 31P and 195Pt NMR spectroscopies show that P 3P′ reacts in dichloromethane solution with Pt(dtp) 2 and Pt(xan) 2 to give five-coordinate [(η 4-P 3P′)Pt(η 1-SS)] + and with Pt(dtc) 2 to give a temperature dependent mixture of [(η 4-P 3P′)Pt(η 1-dtc)] + and [(η 3-P 3P′)Pt(η 2-dtc)] +. All these formulations were confirmed by observation of the intact ions in the ES mass spectra directly from the solutions. [(η 4-P 3P′)Pt(η 1-xan)] + slowly reacts with the free xan ion to give the dithiocarbonate complex (η 3-P 3P′)Pt(η 2-S 2CO). The pendant phosphine in [(η 3-P 3P′)Pt(η 2-dtc)] + undergoes various chemical reactions such as methylation and reaction with sulfur, and the cation behaves as a monodentate phosphine towards Pt(dtp) 2 to give [(η 1-dtp)(η 2-dtp)Pt(η 1-μ 2-η 3-P 3P′)Pt(η 2-dtc)] + which was fully characterised by multi-NMR spectroscopy and confirmed by observation of the intact ion by ESMS. P 2P′ 2 reacts with Pt(dtp) 2 to give [(P 2P′ 2)Pt] 2+, but with Pt(xan) 2 and Pt(dtc) 2 the products are [(η 4-P 2P′ 2)Pt(η 1-SS)] +, but the xanthate complex slowly de-alkylates to give (η 3-P 2P′ 2)Pt(η 2-S 2CO). The identities of the cationic P 2P′ 2 species in solution were confirmed by direct observation of the intact ion by ESMS.

Synthesis and characterization of the molybdenum(IV) oxo-selenolate complex [MoO(Ph 2P(O)CH 2CH 2P(Ph)CH 2CH 2PPh 2)(Se-2,4,6-(CH 3) 3C 6H 2) 2

The presence of adventitious oxygen in the reaction of [(Triphos)MoCl 3] (Triphos = Ph 2PCH 2CH 2P(Ph)CH 2CH 2PPh 2) with NaSeC 6H 2Me 3-2,4,6 in THF leads to the formation of [ fac-MoO(Ph 2P(O)CH 2CH 2P(Ph)CH 2CH 2PPh 2)(SeC 6H 2Me 3-2,4,6) 2). This is the first example of a structurally characterized molybdenum(IV)oxo-selenolato complex. It contains a chelating triphosphine mono-oxide ligand. The formation can be understood in terms of an oxidative addition of dioxygen to the metal centre followed by oxygen atom transfer to the triphos ligand and reduction of molybdenum to molybdenum(IV).

Multinuclear magnetic resonance studies on the interactions of platinum bis(dithiolates) with potentially tridentate phosphine ligands

The reactions of platinum(II) dithiolates Pt(S-S) 2 (S-S=S 2P(OEt) 2, S 2CO nPr, S 2CNEt 2) with two potentially tridentate phosphine ligands have been investigated by multinuclear magnetic resonance spectroscopy. The phosphines used were Ph 2PCH 2CH 2P(Ph)CH 2CH 2PPh 2 (P 2P′) and CH 3C(CH 2PPh 2) 3 (P 3). P 2P′ reacts with all the dithiolates to give complexes of the type [(η 3-P 2P′)Pt(S-S)] + which are thought to be square planar. A square planar complex (η 2-P 2P′)Pt(η 2-S 2P{O}OEt) can be identified at low temperature. In contrast, P 3 acts only as a bidentate ligand in these systems to give square planar complexes of the type [(η 2-P 3)Pt(η 2-S-S)] + which are fluxional at room temperature. Various reactions can be carried out with the pendant phosphine, such as reaction with sulfur and methylation, and these stop the ligand exchange reactions.

Synthesis, structure and structural dynamics of ruthenium(II) bis(2-diphenylphosphinoethyl)phenylphosphine dichloride

Treatment of RuCl 2(PPh 3) 3 with Ph 2PCH 2CH 2P- (Ph)CH 2CH 2PPh 2 (TRIPHOS) yields yellow RuCl 2- (TRIPHOS) 2. RuCl 2{[Ph 2P(CH 2) 2] 2PPh} 2·CHCl 3· (C 2H 5) 2O crystallizes in the triclinic space group P 1 (No. 2) with a = 12.850(3), b = 16.131(5), c = 16.990(5) Å, α=95.77(2)°, β=98.56(2)°, γ=94.96 (2)°, V = 3446(2) Å 3 and Z=2 at 130 K. Refinement yielded R=0.05 for 6635 reflections with I> 2σ( I) and 781 parameters. The ruthenium atom is octahedral with trans chloride ligands, one meridional chelating phosphine, and one monodentate TRIPHOS which bonds through the central phosphorus. 31P NMR data shows hindered rotation of the monodentate TRIPHOS about the RuP bond.

Hydrogenation and hydroformylation catalysis with polydentate phosphine ruthenium complexes

Rhuthenium complexes of the type RuCl 2(tripod) (tripod = N(CH 2CH 2PPh 2) 3, P(CH 2CH 2PPh 2) 3, H 3C-C(CH 2PPh 2) 3) and RuCl 2(tetraphos-1), (tetraphos-1 = (Ph 2PCH 2CH 2P(Ph)CH 2) 2) catalyze the hydrogenation of unsaturated organic substrates such as olefins, aldehydes and ketones at 100° C and 80 atm pressure in ethanol. The hydrogenation rates increase in the presence of ammonium and silver salts, and with increases in temperature and pressure. These complexes also catalyze the hydroformylation of ethylene and 1-hexene at 150 °C and 100 atm of H 2 + CO(H 2:CO = 1) in dioxane with good selectivity for the production of linear aldehydes, but with simultaneous reduction products.

Reactions of metal carbonyl complexes : V. Reactions of Mn(CO) 5X (X = Br, I) with hexaphenyl-1,4,7,10-tetraphosphadecane

The reactions of the potentially tetradentate ligand Tetraphos, [Ph 2PCH 2CH 2P(Ph)CH 2] 2, with Mn(CO) 5X (X = Br, I) are described. The main products of these reactions are fac-Mn(CO) 3 (Tetraphos)Br (two isomers), cis-Mn(CO) 2(Tetraphos)X and [Mn(CO) 3Br] 2(Tetraphos). These products were characterized by elemental analyses, molecular weight determinations, IR spectra and chemical reactions. The possibility that the two isomers of fac-Mn(CO) 3(Tetraphos)Br contain the meso form of the Tetraphos ligand is discussed.