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The tetraphosphine DPPEPM reacts with [PtMe2(cod)] to produce [PtMe2(DPPEPM-PP)] (1) in near quantitative yield. On standing in solution, the free P atoms become oxidized to give [PtMe2(DPPEPM(O)2-PP)] (1a), which has been characterized by X-ray crystallography. In contrast, reactions of DPPEPM with [MCl2(cod)] (M = Pd, Pt) yield ionic products of the form [M(DPPEPM-PP)2]MCl4 (3, 4). When a solution of the platinum complex was allowed to stand, crystals of [Pt(μ-Cl)(μ-DPPEPM)2]Cl3 (5) were obtained. In a third set of reactions, treatment of [PtClR(cod)] (R = Me, Ph) or [PdClMe(cod)] with DPPEPM gives species of the type [MR(DPPEPM-PPP)]Cl (6–8), in which one of the internal P atoms is uncoordinated. Reactions of [PtR2(DPPEPM-PP)] with [ PtR 2 ′ ( cod ) ] or [MCl2(cod)] (M = Pd, Pt), or of [PtR(DPPEPM-PPP)]Cl with [MCl2(cod)], lead to unsymmetrical bimetallic complexes. [PtMe2(μ-DPPEPM)PdCl2] (11) and [PtClPh(μ-DPPEPM)PdCl2] (14) have been characterized crystallographically. Trimetallic complexes of the form [{PtR2(μ-DPPEPM)}2M][MCl4] (M = Pd, Pt, 15–17) are produced by reaction of [PtR2(DPPEPM-PP)] with [MCl2(cod)].

The reaction of Ru(NmCp)(CO)(PPh 3 )I (NmCp = neomenthylcyclopenta-dienyl) with AgSCN occurs with retention of configuration at the ruthenium to give the S-bonded Ru(NmCp)(CO)(PPh 3 )SCN. This was confirmed by determining the X-ray structure of (R) R u -Ru(NmCp)(CO)(PPh 3 )SCN. The reaction of (S) R u -Ru(NmCp)(CO)(PPh 3 )I with AgBF 4 in CH 2 Cl 2 followed by treatment with MeSR gave the following sulfide complexes [(RS) R u -Ru(NmCp)(CO)(PPh 3 ){S(Me)R}]BF 4 (R = CH 2 Ph, Ph and 'Bu). NMR studies have shown that for R = CH 2 Ph the chiral sulfur centre binds to the chiral ruthenium centre with a 33% d.e. and the free energy for inversion of the S-centre is 49 ′ 1 kJ mol - 1 . In contrast, with the bulky phenyl and tert-butyl substituents the chiral ruthenium centre shows an overwhelming preference (≥ 99%) for binding to one enantiomer of the sulfide ligand. Despite this, arguments are presented to show that this ruthenium system is not a suitable chiral auxiliary for use in synthesizing chiral sulfoxides from complexed sulphides.

The chiral ruthenocenes Ru(Cpnm)Cp′ (where Cpnm=neomenthylcyclopentadienyl and Cp′=Cpnm or C5Me5) have been synthesised and oxidised by halogens to the corresponding ruthenium(IV) salts [Ru(Cpnm)Cp′X]Xn (where X=Br or I; Cp′=Cpnm, n=3; Cp′=C5Me5, n=1). These ruthenium(IV) compounds all have, to varying degrees, a tendency to revert back to the ruthenocene(II) compounds (X, Br>I; Cp′, Cpnm>C5Me5). Thus, for [Ru(Cpnm)2Br]Br3 this conversion is complete within two days whereas [Ru(Cpnm)2I]I3 is stable enough for the X-ray structure to have been determined. The electrochemistry and preliminary catalytic studies are reported.

The title homochiral cyclopentadiene ligand C 31 H 30 (i.e., Cp′H, 5 ) has been synthesised from camphor in four steps. The lithium salt of this ligand reacted with [Rh(cod)Cl] 2 to give predominantly racemic ( η 4 -cycloocta-1,5-diene)[ η 5 -1,2,3-triphenyl-4-methyl-7-isopropyl-1H-indenyl]rhodium although the desired RhCp′(cod) complex was formed in 20% yield as an equal mixture of endo 7a and exo 7b isomers. The X-ray structures of 7a and 7b have been determined at room temperature with use of Mo-K α radiation ( λ =0.71069 A). Both compounds crystallise in the orthorhombic space group P 2 1 2 1 2 1 ( D 2 4 , No. 19); for compound 7a , a =13.549(23) A, b =14.490(25) A, c =15.909(14) A, V =3123(8) A 3 , Z =4 and D c =1.303 g cm −3 and the structure was refined to R =0.0488 on the basis of 2545 independent reflections. For the exo isomer 7b , a =13.301(18) A, b =15.599(32) A, c =14.436(19) A, V =2995(10) A 3 , Z =4 and D c =1.359 g cm −3 ; the structure was refined to R =0.0362 on the basis of 4620 independent reflections. Bromine reacts with the compounds 7a and 7b to give the corresponding [{Rh(Cp′)} 2 ( μ -Br 3 )]Br 3 .

The title compounds react with unidentate ligands, L, containing either phosphorus or arsenic donor atoms to yield the corresponding compounds of the type Ru(η5C5Me4Et)(CO)LX; with didentate phosphorus donor ligands the major species formed is the bridged complex {Ru(η5C5Me4Et)(CO)X}2{Ph2P(CH2)nPPh 2} n = 1, X = Br; n = 2, X = Cl). In contrast, unidentate ligands containing nitrogen donor atoms such as pyridine did not react with Ru(η5C5Me4Et)(CO)2Cl although reaction with 1,10-phenanthroline or diethylenetriamine yielded the ionic products [Ru(η5C5Me4Et)(CO)L]+Cl− (L = phen or (NH2CH2CH2)2NH). Reaction of Ru(η5C5Me4Et)(CO)2Br with AgOAc yielded the corresponding acetato complex Ru(η5C5Me4Et)(CO)20Ac. Ru(η5 C5Me4Et)(CO)2X reacts with AgY (Y = BF4 or PF6) in either acetone or dichloromethane to give the useful solvent intermediates [Ru(η5C5Me4Et)(CO)2(solvent)]+Y−, which readily react with ligands L to yield ionic derivatives of the type [Ru(η5C5Me4Et)(CO)2L]+Y− (where L = CO, NCMe, py, C2H4 or MeO2CCCCO2Me).

Phenethyltetraphenylcyclopentadiene has been made from ( R )-1-phenethyl bromide (43.8% e.e) and lithium tetraphenylcyclopentadienide. The syntheses of the hydrogenation catalyst [Rh{C 5 Ph 4 CH(Me)Ph}Br 2 ] 2 and of Rh{C 5 Ph 4 CH(Me)Ph}(C 8 H 12 ) are also reported along with the crystal structure of the latter.

The syntheses and crystal structures of the title compounds are reported. The complex [Ru(η 5 -C 5 H 5 ){( R )-(BINAP)}] + CF 3 SO 3 − is of particular interest in that it contains a tridentate BINAP ligand co-ordinated to the ruthenium through η 2 - bonding to one of the naphthyl rings as well as through both phosphorus atoms. The possible implications of this type of bonding are discussed.

The synthesis and crystal structure of the title compounds are reported. The corresponding tetramethylmenthyl derivative was co-crystallized with triphenylphosphineoxide, ie. as [Rh{C 5 Me 4 -(menthyl)}Cl 2 ] 2 ·2[(C 6 H 5 ) 3 PO]. Both compounds are active hydrogenation catalysts in the presence of Et 3 N but with prochiral alkenes the enantioselectivity is low (i.e. ≤ 13% ee).

The reaction of Ru3(CO)12 with C5Ph5Br yields Ru(η5-C5Ph5)(CO)2Br (1), which reacts with phosphorus donor ligands to give Ru(η5-C5Ph5)(CO)LBr (2: L = PPh3; 3: L = P(OMe)3; 4: L = P(OPh)3). A limited kinetic study has revealed that these carbonyl replacement reactions occur via a dissociative mechanism at a rate significantly faster than those for Ru(Cp′)(CO)2Br (Cp′ = C5H5 or C5Me4Et). The crystal structure of 2 is reported, and reveals that the triphenylphosphine ligand extends into the region occupied by the pentaphenyl propeller, forcing this propeller into an unsymmetrical chiral array. This chiral array complexed to a chiral ruthenium atom gives rise to diastereoisomers which can be seen in the 13C and 31P NMR spectra of 2.

The preparation of the η4-4-2,3,5,6-tetramethyl-1,4-benzoquinonecomplex [CO(C5Me5)(C10H12O2)] (I) is reported. Complex I undergoesreversible protonation to yield the 2-6-η-4-hydroxy-1-oxo-2,3,5,6-tetramethylcyclohexadienyl complex [Co(C5Me5)(C10H13O2)BF4 (II) and diprotonation to yield the η6-6-1,4-dihydroxy-2,3,5,6-tetramethylbenzene complex [Co(C5Me5)(C10H14O2)] (BF4)2 (III). Methylation of complex I with MeI/AgPF6 gives the 26-η-4-methoxy-1-oxo-2,3,5,6-tetramethylcyclohexadienyl complex [Co(C5Me5)(C11H15O2])PF6 (IV). In trifluoroacetic acid solution complex IV is protonated to form the η6-1-hydroxy-4-methoxy-2,3,5,6-tetramethylbenzene cation [Co(C5Me5)-(C11H16O2)]2+

The preparation of [Ru(η 5 -C 5 Me 4 Et)(CO) 2 ] 2 has been described and its structure determined by X-ray crystallography. The crystals are monoclinic with space group C2/m and a = 11.94(2), b = 12.158(2), c = 9.433(2)A and β = ll3.95(1)°. In the solid state the dimeric molecule has crystallographically imposed C 2h symmetry (i.e. trans conformation) with two bridging and two terminal carbonyl ligands; this structure is retained in solution. The structure is compared with those of the related complexes, [M(η 5 -C 5 H 5 )(CO) 2 ] 2 (M = Fe and Ru).

Reaction of [M(η 5 -C 5 Me 5 )Cl 2 ] 2 with AgPF 6 in acetone gave [M(η 5 -C 5 Me 5 )-(Me 2 CO) 3 ] [PF 6 ] 2 (Ia, M  Rh; Ib, M  Ir). Heating an acetone solution of Ia gave [{Rh(η 5 -C 5 Me 5 )} 2 (PO 2 F 2 ) 3 ]PF 6 (IIa). Heating an acetone solution of Ib gave the η 5 -(2-hydroxy-4-methylpentadienyl)(η 5 -pentamethylcyclopentadienyl)iridium cation; an intermediate in this reaction, the η 5 -(2,4-dimethyl-1-oxapentadienyl)(η 5 -pentamethylcyclopentadienyl)iridium cation could also be prepared from Ib and mesityl oxide. Possible reaction mechanisms are discussed.

The acetone solvent complexes (Me2CO)3][PF6]2, (M  Rh, Ir) prepared in situ from [M(η5-C5Me5)Cl2]2 and AgPF6 in acetone, reacted with phenol to give the hydrogen-bonded dimeric phenol complexes (II) [M(η5-C5Me52](η6)-PHO-H...O(η6-)Ph][PF6]3; these were easily deprotonated with base to the corresponding η5-oxocyclohexadienyl complexes [M(η5-C5Me5(η5-C6H5O)]PF6, which showed v(CO) at 1630 (RH) and 1635 (Ir) cm-1. An unstable η6-phenol iridium complex, [Ir(c5Me5)(PhOH][PF6]2, was obtained on protonation of (II, M  Ir).

The acetone solvent complexes [M(C 5 Me 5 )(Me 2 CO) 3 ](PF 6 ) 2 (Ila, M = Rh; Ilb, M = Ir) reacted with L to give [M(C 5 Me 5 )L 3 ](PF 6 ) 2 , where L = (MeO) 3 P, (EtO) 3 P, or Me 2 PhP) but (MeO) 3 P reacted further with Ilb to give [HIr(C 5 Me 5 ){P(OMe) 3 } 2 ]PF 6 . (PhO) 3 P reacted with II to give the ortho -metallated products [M{C 6 H 4 OP(OPh) 2 } {P(OPh) 3 } (C 5 Me 5 )PF 6 , while [Rh(C 5 Me 5 )(MeCN) 3 ](PF 6 ) 2 gave [Rh(C 5 Me 5 )(MeCN) 2 (PPh 3 )](PF 6 ) 2 wiht Ph 3 P. The coordination of ligands to [M(C 5 Me 5 )] 2+ is subjeced to strong steric restraints and only one or two molecules of the bulkier phosphines and phosphites can coordinate.

The stereochemistry of substitution reactions of complexes of the type [Ru(η 5 -C 5 H 4 R*)(CO)(PPh 3 )L] n+ (R* = menthyl or R = neomenth n = 1, L = NCCH 3 or NCCD 3 has been studied by X-ray crystallography. Circular Dichroism and 1 H, 13 C and 31 P NMR spectroscopy. All the reactions investigated have been unequivocably proved to occur with ⩾ 94% retention of configuration at the ruthenium atom. Thus ( S )-Ru(η 5 -C 5 H 4 R*)(CO)(PPh 3 )Cl reacts with NaI to give ( R )-Ru(η 5 -C 5 H 4 R*)(CO)(PPh 3 )I (R* = menthyl or neomenthyl) and reaction of Ru(η 5 -C 5 H 4 R*)CO(PPh 3 )X (R*=menthyl, ( S ) Ru , X = Cl; R* = neomenthyl, (R) Ru , X = I) with AgY in acetonitrile yields the corresponding complex ( R )-[Ru(η 5 - C 5 H 4 R*)(CO)(PPh 3 )(NCCH 3 )]Y (Y = PF 6 or BF 4 ). An X-ray structure determination of [Ru(η 5 -C 5 H 4 R*)(CO)(PPh 3 )NCCH 3 ]PF 6 (R* = neomenthyl) has confirmed that the absolute configuration of the ruthenium centre is R . The crystals are orthorhombic, space group P 2 1 2 1 2 1 (No. 19) with a 10.400(2), b 15.850(4), c 24.740(5) A and Z = 4. The structure was solved via the heavy-atom method and refined to R = 0.036 using 4183 diffractometer data with I ⩾ 1.56( I ). CD 3 CN undergoes exchange with the coordinated acetonitrile in ( R )-[Ru(C 5 H 4 R*)(CO)(PPh 3 )(NCCH 3 )]BF 4 (R* = neomenthyl) with retention of configuration at ruthenium and reaction of ( R )-[Ru(η 5 -C 5 H 4 R*)(CO)(PPh 3 )NCCD 3 ]BF 4 with NaI regenerates ( R )-[Ru(η 5 -C 5 H 4 R*)(CO)(PPh 3 )I] (R* = neomenthyl).

Ru(C5H5)(CO)2H, prepared in situ from Ru3CO)12, reacts with bisphosphines L2 to give Ru(C5H5)L2H quantitatively [L2 = Ph2P(CH2)nPPh2 n = 2 or 4; L2 = (R)-Ph2PCH2CH(Me)PPh2].

The title compound has been prepared by reaction of trimethylphosphite with η 6 -benzene(σ 5 -ethyltetramethylcyclopentadienyl)rhodium(III) hexafluorophosphate. IR and 1 H, 13 C and 31 P NMR spectra of the product are reported.