Ph2PCH2CH2P Ph Research Articles

Molecular orbital study of the bonding and reactivity of the diisocyanide complexes trans-[Mo(CNR) 2(Ph 2PCH 2CH 2PPh 2) 2] and derived aminocarbyne compounds

The bonding structure, properties and reaction patterns of the isocyanide and aminocarbyne-type complexes of molybdenum have been investigated with the aid of EHMO-SCCC calculations and of frontier orbital theory. The results indicate that (i) β-protonation of a ligating isocyanide, in either the trans-[Mo(CNMe) 2(dppe) 2] ( 1) or trans-[Mo(CNHMe)(CNMe)(dppe) 2] +, is predominantly charge-controlled, whereas the α-nucleophilic attack at the dicarbene-type complex trans-[Mo(CNHMe) 2(dppe) 2] 2+ is orbitally controlled, and (ii) electrophilic attack should preferentially occur at the Mo atom of a molybdenum complex involving linear isocyanide ligands but at the N atoms of a complex with bent isocyanide ligands. The conversion of the hydride into the aminocarbyne complex, the oxidation of 1, and its oxidative-addition reactions with halogens are interpreted in terms of FMO theory.

Synthesis and crystal structure of the complex double salt [Re(NCC 6H 4Me-4) 2(Ph 2PCH 2CH 2PPh 2) 2][ReF 2(Ph 2PCH 2CH 2PPh 2) 2] [BF 4] 2

Reaction of NCC 6H 4Me-4 with trans-[ReCl(N 2)(dppe) 2] (dppe = Ph 2PCH 2CH 2PPh 2) in the presence of TlBF 4 has given the formation of trans-[Re(NCC 6H 4Me-4) 2(dppe) 2][BF 4] · trans-[ReF 2(dppe) 2][[BF 4], the crystal structure of which has been determined.

The X-ray crystal structures of [Mo(C [tbnd]CPh)(Ph 2PCH 2CH 2PPh 2)(η-C 7H 7)] and [Mo(C [tbnd]CPh)(Ph 2PCH 2CH 2PPh 2)(η-C 7H 7)] [BF 4] (C 7H 7 = cycloheptatrienyl): an investigation of metal [sbnd]alkynyl bonding

Single crystal X-ray diffraction studies have been carried out on the cycloheptatrienylmolybdenum alkynyl complexes [Mo(C CPh)(dppe)(η-C 7H 7)] ( 1) and [Mo(C CPh)(dppe)(η-C 7H 7)][BF 4] ( 2-[BF 4]) (dppe = Ph 2PCH 2CH 2PPh 2) to investigate the structural effects of one-electron oxidation of 1. The major structural alterations resulting from oxidation of 1 to 2-[BF 4] are an increase of 0.061(2)Åin the mean Mo phosphorus separation and a decrease of 0.071(10)Åin the Mo alkynyl carbon bond length. The mean Mo to cycloheptatrienyl carbon distance and the alkynyl C C bond length are virtually unchanged. These observations are consistent with a metal-based redox site in 1 and, in conjunction with the results of electrochemical and infrared studies, suggest that the alkynyl ligand in 1 acts predominantly as a σ-donor to molybdenum with any contribution to the metal alkynyl bond from a dπ (metal) → π* (alkynyl) interaction being relatively insignificant in this particular example.

CX and CH cleavage by electrochemically generated non-linear [PtL 2] complexes

The electrochemical reduction of [PtX 2L 2] (X = halide, L 2 = bidentate diphosphine: Ph 2PCH 2CH 2PPh 2, dppe; Cy 2PCH 2CH 2PCy 2, dcpe; Cy 2P{CH 2} 3PCy 2, dcpp) has been used as a method of generating non-linear [PtL 2] compounds whose reactivity with substrates ArX (X = Cl, Br, CN, H, CCPh) has been examined. Generation of [PtL 2] (L 2 = dppe or dcpe) in the presence of excess PhX (X = Cl, Br) produces [PtXPhL 2] efficiently. Similarly, generation of [PtL 2] (L 2 = dppe or dcpe) in the presence of PhCCPh results in trapping to form [PtL 2(PhCCPh)]. Generation of [PtL 2] (L 2 = dppe or dcpe) in the presence of PhCN or PhH results in indiscriminate reactions that do not produce tractable products. In contrast, reduction of [PtCl 2(dcpp)] in CH 3CN/C 6H 6/Bu 4NClO 4 produces [PtHPh(dcpp)] with considerable selectivity via aromatic CH activation by [Pt(dcpp)]. At room temperature the complex [PtHPh(dcpp)] undergoes exchange with C 6D 6 to generate [PtD(C 6D 5)(dcpp)].

Synthesis and crystal structure of [MoH 3(CCBu t)(Ph 2PCH 2CH 2PPh 2) 2], a trihydrido-alkynyl complex

Reaction of Bu tCCH with trans-[Mo(N 2) 2(dppe) 2] (dppe = Ph 2PCH 2CH 2PPh 2) gives [MoH 3(CCBu t)(dppe) 2], whose X-ray structure is reported.

Preparation and structural properties of mononuclear and binuclear ruthenium(II) cyclopentadienyl complexes with 4-cyanopyridine and 4-cyanopyridine 1-oxide

Reactions of [Ru(η 5-C 5H 5)L 2Cl] (L = PPh 3 or AsPh 3, L 2 = Ph 2PCH 2CH 2PPh 2 or Ph 2PCH 2PPh 2) have been carried out with 4-cyanopyridine and 4-cyanopyridine 1-oxide in the presence of suitable anions (PF − 6 or BPh − 4). The reaction products were found to be cationic mono- and binuclear complexes which have been characterized by elemental analyses, spectroscopic (IR, UV-vis and NMR) and electrochemical studies. Conductivity measurements have also been carried out to confirm the charges on these cationic species.

Synthesis and reactions of phenylacetylide iridium(I) and rhodium(I) complexes

The complexes Ir(CCPh)(cod)(PPh 3) 2 and Rh(CCPh)(cod)(PCy 3) (cod = cycloocta-1,5-diene; Cy = cyclohexyl) have been prepared by reaction of the corresponding [M(μ-OMe)(cod)] 2 dimers with PPh 3 or PCy 3 and HCCPh. Ir(CCPh) (cod)(dppe) (dppe = Ph 2PCH 2CH 2PPh 2) has been made by treatment of Ir(CCPh)(cod)(PCy 3) with dppe, and M(CCPh)(CO)(PCy 3) 2 (M = Ir, Rh) have been made by carbonylation of the diolefin M(CCPh)(cod)(PCy 3) compounds in the presence of PCy 3. The preparation of the related dicarbonyl Ir(CCPh)(CO) 2(dppe) complex by reaction of Ir(CCPh)(cod)(dppe) with carbon monoxide is also reported. Ir(CCPh)(CO) 2(dppe) reacts with hydrogen to give the dihydrido complex IrH 2(CCPh)(CO)(dppe).

Preparation of mixed dithio-β-diketonato (tertiary phosphine) palladium(II) complexes

Neutral and cationic palladium(II) dithio-β- diketonate complexes of general formula Pd{CH 3C- (S)CHC(S)CH 3}X(L) and [Pd{CH 3C(S)CHC(S)CH 3}{(L-L′)}]Y (L = various monodentate tertiary phosphines; L-L′ = Ph 2PCH 2CH 2PPh 2, o-CH 2 = CHC 6H 4PPh 2; X = Br, I; Y = I, PF 6, BPh 4) are described. These are direct analogues of the nickel dithio-β- diketonate tertiary phosphine complexes which are precursors to highly active olefin oligomerization catalysts.

Synthesis of transition-metal Lewis acid adducts of trans-[ReCl(CNR)(Ph 2PCH 2CH 2PPh 2) 2] (R = alkyl). A chemical and a quantum-chemical study of electrophilic β-addition to ligating isocyanide

Treatment of trans-[ReCl(CNR)(dppe) 2] (R = Me or Bu t, dppe = Ph 2PCH 2CH 2 PPh 2) with CoCl 2(THF) 1.5, [ReOCl 3(PPh 3) 2] or [WCl 4L 2] (L = PPh 3 or PEtPh 2) affords the dinuclear adducts [ReCl(CN(M)R)(dppe) 2] (M = CoCl 2(THF), ReOCl 3(PPh 3) or WCl 4L, respectively) (formed via electrophilic β-addition of the electron-acceptor molecules to the isocyanide ligands), which undergo dissociation oxidation (for M = CoCl 2(THF) or ReOCl 3(PPh 3)). These reactions are considered in the light of results of extended Hückel calculations.

Ligand-centred coupling of the alkynyl radical cations [Mo(CCR)(Ph 2PCH 2CH 2PPh 2)(η-C 7H 7)] + (R = Ph or Bu n: crystal structure of the dimeric product [Mo 2(Ph 2PCH 2CH 2PPh 2) 2(η-C 7H 7) 2(μ-C 4R 2)][PF 6] 2 (R = Ph)

The radical cations [Mo(CCR)(dppe)(η-C 7H 7)] + (R = Ph or Bu n); dppe = Ph 2PCH 2CH 2PPh 2) undergo coupling at C β of the alkynyl ligand to afford the divinylidene-bridged, dimeric products [Mo 2(dppe) 2(η-C 7H 7) 2(μ-C 4R 2)] 2+, characterised crystallographically for R = Ph.

Studies on the reactivity of the halo-hydride complexes [M(η 5-C 5H 5) 2HX] (M = Mo, W; X = Cl, Br, I)

A convenient preparation of the cations [Mo(η 5-C 5H 5) 2HL] + and [Mo(η 5-C 5H 5) 2H(LL)] + from [Mo(η 5-C 5H 5) 2HI] ( 1), L and TlPF 6(BF 4) is described for L = CO, C 2H 4, PMe 2Ph, PEt 2,Ph, PPh 3, NH 3, NCMe and LL = Ph 2PCH 2PPh 2, (dppm), H 2NCH 2CH 2NH 2 (en). Complex 1 and butadiene give [Mo(η 5-C 5H 5) 2(η 3-CH 3C 3H 4)]BF 4. The chloro and bromo analogues of 1 are less reactive, and the W analogue of 1 does not react under the conditions used for 1. Reaction of 1 with Ph 2PCH 2CH 2PPh 2 (dppe) gives the cation [Mo(η 5-C 5H 5)(η 4-C 5H 6)dppe] + ( 18) in the presence or absence of TlPF 6. The deuterido analogue of 1, 1d gives 18d having the deuterium on the exo face of the C 5H 5D ring.

The reactions of trans-[MoH 4(Ph 2PCH 2CH 2PPh 2) 2] with RCO 2CCH (R = Me or Et) in the presence of acids. Preparation of hydrido-σ-alkenyl complexes of molybdenum(IV)

Reaction of trans-[MoH 4(dppe) 2] (dppe = Ph 2PCH 2CH 2PPh 2) with RCO 2CCH (R = Me or Et) in the presence of HBF 4 in tetrahydrofuran (thf) gives the carboxylato-σ-alkenyl complexes [ MoH 2{CHCHC(O )OR}(dppe) 2]BF 4, whereas if HBr is used as acid, decarboxylation of the alkenyl ligand occurs to give the complexes [MoBrH 2(CHCHR)(dppe) 2].

The chemistry of cycloheptatrienyl complexes of molybdenum and tungsten: synthesis and redox chemistry of some phosphine- and phosphite-substituted halide and acetonitrile derivatives

Reaction of [Mo(η-C 6H 5Me)(η-C 7H 7)][PF 6] (C 6H 5Me = toluene) with two equivalents of P(OMe) 3 in refluxing acetonitrile affords [Mo(NCMe){P(OMe) 3} 2(η-C 7H 7)][PF 6], which is a precursor for the neutral complex [MoI{P(OMe) 3} 2(η-C 7H 7)] ( 2) and the radical cation [MoCl{P(OMe) 3} 2(η-C 7H 7)][PF 6] ( 3). Treatment of [WI(CO) 2(η-C 7H 7)] with PPh 3 gives [WI(CO)(PPh 3)(η-C 7H 7)] ( 6), which is a starting material for the synthesis of [W(CO)(dppe)(η-C 7H 7)][PF 6] (dppe = Ph 2PCH 2CH 2PPh 2) and hence [W(NCMe)(dppe)(η-C 7H 7)][PF 6] ( 9). Reaction of 9 with LiCl gives a mixture of [WCl(dppe)(η-C 7H 7)][PF 6] ( 14) and [WCl(dppe)(η-C 7H 7)]. Cyclic voltammetric studies on 2, 3, 6, 9, [Mo(NMe)(dppe)(η-C 7H 7)][PF 6] ( 10), and 14 reveal reversible one-electron transfer processes, and [MoI{P(OMe) 3} 2(η-C 7H 7)][BF 4] ( 4), [MoCl{P(OMe) 3} 2(η-C 7H 7)] ( 5) and [M(NCMe)(dppe)(η-C 7H 7)][PF 6] 2 ( 11, M = W; 12, M = Mo) have been isolated by use of chemical redox reagents. The radicals 3, 4, 11, 12 and 14 have been studied by ESR spectroscopy.

Synthesis and some reactions of Fe(CO) 2(dppe)(SR) 2 and Fe 3(CO) 6(SAr) 6 complexes. The crystal structure of cis, cis,cis-Fe(CO) 2(dppe)(SPh) 2

The complexes Fe(CO) 2(dppe)(SR) 2(dppe)  Ph 2PCH 2CH 2PPh 2; R  s-Bu, Ph, p-C 6H 4Me, p-C 6H 4OMe, p-C 6H 4NHC(O)Me) have been synthesized from Fe 2+ salts by treatment with CO in the presence of dppe and RS − and the crystal structure of the Fe(CO)(dppe)(SPh) 2 derivative has been determined. The ligands occupy cis,cis,cis positions and there are two enantiomeric molecules in the asymmetric unit (space group P 1 − ) of the crystal. The Fe(CO) 2(dppe)(SR) 2 complexes from 1 2 adducts with HgCl 2. In the abscence of dppe, methanol solutions of Fe 2+ and ArS − ( 1 2 ; Ar  Ph, p-C 6H 4Me, p-C 6H 4Me, p-C 6H 4OMe) take up CO to give the trinuclear thiolato complexes Fe 3(CO) 6(SAr) 6.

Bridging rather than chelation in the substitution chemistry of the osmium(I) complex [Os 2(MeCO 2) 2(CO) 6] with potentially chelating phosphines and arsines

Substitution of the osmium(I) dimer [Os 2(MeCO 2) 2(CO) 6] with monophosphines has been previously shown to give mono- and disubstituted products with the introduced ligands exclusively trans to the OsOs bond. This has allowed the preparation of the complexes, [Os 2(MeCO 2) 2(CO) 4(PPh 3)(η 1-L)] and [Os 2(MeCO 2) 2(CO) 4(η 1-L) 2], in which the ligands L are Ph 2PCH 2PPh 2 (dppm), Ph 2PCH 2CH 2PPh 2 (dppe) or 1,2-C 6H 4(AsMe 2) 2 (diars). These ligands are normally found to be chelating or bridging but here are coordinated through a single heteroatom, but these complexes show no tendency to lose CO ligands cis to the metal-metal bonds to allow the ligands L either to chelate or bridge. There is, however, a strong tendency to form oligomers with bridging diphosphine ligands linking separate OS 2 groups, but the designed synthesis of chains Of Os 2 units has failed because of slow redistribution reactions involving cleavage of the OsLOs bridges.

Thermodynamics of homogeneous hydrogenation: Part V. Hydrogenation of cyclohexene catalyzed by Rh(I) complexes of the bidentate (NP) ligand, (2-(diphenylphosphino)ethyl)benzylamine

The oxidative addition of H 2 to the Rh(I) complexes of the bidentate NP ligand, (2-(diphenylphosphino)ethyl)benzylamine, viz. [Rh(NP)(Cl)(CO)] 1, ▪ 2, [Rh(NP) 2Cl] 3 proceeds at 30 °C and l atm H 2 m 7:3 benzene-ethanol solvent with the formation of the thermodynamically stable cis dihydrides [Rh(NP)(Cl)(CO)(H) 2] 1a, 1b, ▪ 2a, 2b and [Rh(NP) 2(H) 2Cl] 3a, 3b characterized by their hydride NMR in situ. The homogeneous hydrogenation of cyclohexene catalyzed by complexes 1 – 3 was investigated in the temperature range 10 – 40 °C at 0.6 – 1 atm of H 2 partial pressure. Thermodynamic parameters for the formation of the Rh(III) dihydrido complexes of 1 – 3 and the corresponding monoolefin complexes of Rh(I) were computed. The activation parameters corresponding to the rate constant k for the homogeneous hydrogenation of cyclohexene were also calculated. The catalytic activity of the complexes decreases in the order 2 > 3 ⪢ 1. Except complex 1, the catalytic activity of the bidentate complexes of Rh(I) 2 and 3 is higher than those of RhCl(diphos) 4 (diphos = Ph 2PCH 2CH 2PPh 2) and RhCl(NP 2) 5 (NP 2 = H-N(CH 2CH 2-PPh 2) 2). This is because the stabilities of the hydrides of 2 and 3 are lower than those of 4 and 5.

Pseudohalogeno-Metallverbindungen: LXX. Neue stabile Metallcyanid-Bortrifluorid Addukte; kristallstrukturanalyse von (η 5-C 5H 5)(Ph 3P) 2Ru(CNBF 3)

Adducts of the metal cyanides and borontrifluoride, (η 5-C 5H 5L 2MCNBF 3 (M = Fe, Ru; L = PPh 3, 1 2 Ph 2PCH 2CH 2PPh 2), (η 5-C 5H 5)(OC)(Ph 3P)FeCNBF 3, (R 3P) 2Pt(CNBF 3) 2 (R = Et, Ph) are obtained after use of tetrafluoroboric acid Et 2O or BF 3·Et 2O, respectively. The crystal structure of (η 5-C 5H 5(Ph 3P) 2-RuCNBF 3 has been determined (∢RuCN 174.6, ∢CNB 173.5°; Ru-C 1.95, C-N 1.15, N-B 1.56 Å).

Mononuclear alkynyl, alkenyl, alkylidyne and alkylidene complexes of molybdenum and tungsten from reactions of 1-alkynes with hydride complexes. Crystal Structure of [WH 2(CCCO 2Me) 2(Ph 2PCH 2CH 2PPh 2) 2

[WH 2(CCR) 2(dppe) 2] (R = Ph or CO 2Me; dppe = Ph 2PCH 2CH 2PPh 2) react with HBF 4 to give [WF(CCH 2CO 2Me)(dppe) 2] and [WF(CHCH 2Ph)(dppe) 2]BF 4; the X-ray structure of [WH 2(CCCO 2Me) 2(dppe) 2] is reported. With HBF 4, [MoH 4(dppe) 2] reacts with R′CO 2CCH (R′ = Me or Et) t give [ MoH 2{CHCC(O )OR′}(dppe) 2]BF 4, but with HBr, [MoBrH 2(CHCHR′)(dppe) 2] are formed.

The preparation and structure of the bis-vinyl ether complex Pt(Ph 2PCH 2CH 2PPh 2)[(MeO 2C)C[dbnd]C(OMe)(CO 2Me)] 2

Reaction of the [Pt(dppe)] 2+ cation (where dppe = Ph 2PCH 2CH 2PPh 2) with the activated acetylene dimethyl acetylenedicarboxylate in methanol solution results in the formation of the bis-vinyl ether complex Pt(dppe)[(MeO 2C)CC(OMe)(CO 2Me)] 2. The compound is characterized by infrared, 1H and 31P( 1H) NMR spectroscopy, elemental analysis and X-ray crystallography.

Tri- and tetra-metallic complexes containing phospha-alkyne ligands. First examples of μ 3(η 2-⊊) bonded phospha-alkynes; crystal and molecular structure of [Fe 2Pt(Ph 2PCH 2CH 2PPh 2)(CO) 6(Me 3CCP)

A new μ 3(η 2-⊊) coordination mode for a phospha-alkyne has been established in the complexes [Fe 2pt(Ph 2PCH 2CH 2PPh 2)(CO) 6(Me 3CCP)] and [Fe 3Pt{(Ph 2PCH 2) 3CMe}(CO) 10(Me 3CCP)].