Synthesis, Molecular Structure and Derivatization of the Triruthenacarborane Cluster Compound [1-SMe2-2,2-(CO)2-7,11-(Μ-H)2-2,7,11-{Ru2(CO)6}-closo-2,1-RuCB10H8]*

In toluene at reflux temperatures [Ru₃(CO)₁₂] and 7-SMe₂-nido-7-CB₁₀H₁₂ give the charge-compensated cluster complex [1-SMe₂-2,2-(CO)₂-7,11-(μ-H)₂-2,7,11-Ru₂(CO)₆-closo-2,1-RuCB₁₀H₈] (1) . Treatment of 1 with dppm in THF affords [1-SMe₂-2,2-(CO)₂-7,11-(μ-H)₂-2,7,11-Ru₂(μ -dppm)(CO)₄-closo-2,1-RuCB₁₀H₈] (2) [dppm = bis(diphenylphosphino)methane; THF = tetrahydrofuran]. The latter complex on heating in THF with [ ]F yields the salt [ ][1-SMe-2,2-(CO)₂-7,11-(μ-H)₂-2,7,11-Ru₂(μ -dppm)(CO)₄-closo-2,1-RuCB₁₀H₈] (3). Reaction of 3 with [AuCl(PPh₃)] and Tl[PF₆] gives the neutral zwitterionic complex [1-S(Me)Au (PPh₃)-2,2-(CO)₂-7,11-(μ-H)₂-2,7,11-Ru₂(μ-dppm)(CO)₄-closo-2,1-RuCB₁₀H₈] (4). The structures of 1, 3 and 4 were determined by single-crystal X-ray diffraction studies.*Dedicated to Professor F. Albert Cotton on the occasion of his 75th birthday, in appreciation of our long friendship and in recognition of his outstanding contributions to the study of complexes with metal–metal bonds.     

Synthesis of new heterometallic complexes by tin-sulfur bond cleavage of pySSnPh3 (pySH = pyridine-2-thiol) at triruthenium and triosmium centres

The ruthenium-tin complex, [Ru₂(CO)₄(SnPh₃)₂(μ-pyS)₂] (1), the main product of the oxidative-addition of pySSnPh₃ to Ru₃(CO)₁₂ in refluxing benzene, is [Ru(CO)₂(pyS)(SnPh₃)] synthon. It reacts with PPh₃ to give [Ru(CO)₂(SnPh₃)(PPh₃)(κ²-pyS)] (2) and further with Ru₃(CO)₁₂ or [Os₃(CO)₁₀(NCMe)₂] to afford the butterfly clusters [MRu₃(CO)₁₂(SnPh₃)(μ₃-pyS)] (3, M=Ru; 4, M=Os). Direct addition of pySSnPh₃ to [Os₃(CO)₁₀(NCMe)₂] at 70 °C gives [Os₃(CO)₉(SnPh₃)(μ₃-pyS)] (5) as the only bimetallic compound, while with unsaturated [Os₃(CO)₈{μ₃-PPh₂CH₂P(Ph)C₆H₄}(μ-H)] the previously reported [Os₃(CO)₈(μ-pyS)(μ-H)(μ-dppm)] (6) and the new bimetallic cluster [Os₃(CO)₇(SnPh₃){μ-Ph₂PCH₂P(Ph)C₆H₄}(μ-pyS)[(μ-H)] (7) are formed at 110 °C. Compounds 1, 2, 4, 5 and 7 have been characterized by X-ray diffraction studies.     

Synthesis of Co2Pt, Co2Pd and MoPd2 mixed-metal clusters with the P–N–P assembling ligands (Ph2P)2NH (dppa) and (Ph2P)2NMe (dppaMe). Crystal structure of [Co2Pt(μ3-CO)(CO)6(μ-dppa)]

Heterometallic triangular platinum–cobalt, palladium–cobalt and palladium–molybdenum clusters stabilized by one or two bridging diphosphine ligands such as Ph₂PNHPPh₂ (dppa) or (Ph₂P)₂NMe (dppaMe) or by mixed ligand sets Ph₂PCH₂PPh₂ (dppm)/dppa have been prepared with the objectives of comparing the stability and properties of the clusters as a function of the short-bite diphosphine ligand used and of the metal carbonyl fragment they contain. Ligand redistribution reactions were observed during the purification of [Co₂Pd(μ₃-CO)(CO)₄(μ-dppa)(μ-dppm)] (4) by column chromatography with the formation of [Co₂Pd(μ₃-CO)(CO)₄(μ-dppm)₂] and the dinuclear complex [(OC)₂ Cl] (5). The latter was independently prepared by reaction of [Pd(dppa-P,P′)₂](BF₄)₂ with Na[Co(CO)₄]. Attempts to directly incorporate the ligand (Ph₂P)₂N(CH₂)₃Si(OMe)₃ (dppaSi) into a cluster or to generate it by N-functionalization of coordinated dppa were unsuccessful, in contrast to results obtained recently with related clusters. The crystal structure of [Co₂Pt(μ₃-CO)(CO)₆(μ-dppa)] (1) has been determined by X-ray diffraction.     

The insertion of acetylene into the formal ruthenium-phosphorus bonds of closo-[Ru4(μ4-PPh)2(μ2-CO)(CO)10. Crystal structure of [Ru4(μ4-PPh){μ4-η-P(Ph)CHCH}(μ2-CO)(CO)10]

Treatment of closo-[Ru₄(μ₄-PPh)₂(μ₂-CO)(CO)₁₀] with acetylene under ambient conditions leads to the insertion of the acetylene into the skeletal framework of the cluster and the formation of [Ru₄(μ₄-PPh){μ₄-η³-P(Ph)CHCH}(μ₂-CO)(CO)₁₀], the structure of which has been determined X-ray crystallographically.     

Olefin epoxidation catalyzed by [Ru(TDL)(tmeda)H2O] complexes (TDL = tridentate Schiff-base ligand; tmeda = tetramethylethylenediamine)

Mixed-chelate complexes of ruthenium have been synthesized using tridentate Schiff-base ligands (TDLs) derived from condensation of 2-aminophenol or 2-aminobenzoic acid with aldehydes (salicyldehyde, 2-pyridinecarboxaldehyde), and tmeda (tetramethylethylenediamine). [Ru^III(hpsd)(tmeda)(H₂O)]⁺ (1), [Ru^III(hppc)(tmeda)(H₂O)]²⁺ (2), [Ru^III(cpsd)(tmeda)(H₂O)]⁺ (3) and [Ru^III(cppc)(tmeda)(H₂O)]²⁺ (4) complexes (where hpsd²⁻ = N-(hydroxyphenyl)salicylaldiminato); hppc⁻ = N-(2-hydroxyphenylpyridine-2-carboxaldiminato); cpsd²⁻ = (N-(2-carboxyphenyl)salicylaldiminato); cppc⁻ = N-2-carboxyphenylpyridine-2-carboxaldiminato) were characterized by microanalysis, spectral (IR and UV–vis), conductance, magnetic moment and electrochemical studies. Complexes 1–4 catalyzed the epoxidation of cyclohexene, styrene, 4-chlorostyrene, 4-methylstyrene, 4-methoxystyrene, 4-nitrostyrene, cis- and trans-stilbenes effectively at ambient temperature using tert-butylhydroperoxide (t-BuOOH) as terminal oxidant. On the basis of Hammett correlation (log k_rel vs. σ⁺) and product analysis, a mechanism involving intermediacy of a [Ru–O–OBu^t] radicaloid species is proposed for the catalytic epoxidation process.     

The synthesis, structure and reactivity of aldehyde substituted η-allylic complexes of molybdenum

Reaction of cis-[Mo(NCMe)₂(CO)₂(η⁵-L)][BF₄] (L=C₅H₅ or C₅Me₅) with 1-acetoxybuta-1,3-diene gives the cationic complexes [Mo{η⁴-syn-s-cis-CH₂CHCHCH(OAc)}(CO)₂(η⁵-L)][BF₄], which, on reaction with aqueous NaHCO₃/CH₂Cl₂, afford good yields of the anti-aldehyde substituted complexes [Mo{η³-exo-anti-CH₂CHCH(CHO)}(CO)₂(η⁵-L)] 2 (L=C₅Me₅), 4 (L=C₅H₅)]. The corresponding η⁵-indenyl substituted complex 5 was prepared by protonation (HBF₄·OEt₂) of [Mo(η³-C₃H₅)(CO)₂(η⁵-C₉H₇)] followed by addition of CH₂=CHCH=CH(OAc) and hydrolysis (aq. NaHCO₃/CH₂Cl₂). An X-ray crystallographic study of complex 2 confirmed the structure and showed that there is a contribution from a zwitterionic form involving donation of electron density from the molybdenum to the aldehyde carbonyl group. Treatment of 2 and 4, in methanol solution, with NaBH₄ afforded the alcohols [Mo{η³-exo-anti-CH₂CHCHCH₂(OH)}(CO)₂(η⁵-L)] [6 (L=C₅H₅), 8 (L=C₅Me₅)]; however, prolonged (30 h) reaction with NaBH₄/MeOH surprisingly gave good yields of the methoxy-substituted complexes [Mo{η³-exo-anti-CH₂CHCHCH₂(OMe)}(CO)₂(η⁵-L)] [7 (L=C₅H₅), 9 (L=C₅Me₅)], the structure of 7 being confirmed by single crystal X-ray crystallography. This methoxylation reaction can be explained by coordination of the hydroxyl group present in 6 and 8 onto B₂H₆ to form the potential leaving group HOBH₃⁻, which on ionisation affords [Mo(η⁴-exo-buta-1-3-diene)(CO)₂(η⁵-L)]⁺ which is captured by reaction with OMe⁻. Complex 8 is also formed in good yield on reaction of 2 with HBF₄·OEt₂ followed by treatment of the resulting cation [Mo{η⁴-exo-s-cis-syn-CH₂CHCHCH(OH)}(CO)₂(η⁵-C₅Me₅)][BF₄] with Na[BH₃CN]. Reaction of 4 with the Grignard reagents MeMgI, EtMgBr or PhMgCl afforded moderate yields of the alcohols [Mo{η³-exo-anti-CH₂CHCHCH(OH)R}(CO)₂(η⁵-C₅H₅)] [11 (R=Me), 12 (R=Et), 13 (R=Ph)]. Similarly, treatment of 2 with MeLi gave the corresponding alcohol 14. An attempt to carry out the Oppenauer oxidation [Al(OPr′)₃/Me₂CO] of 11 resulted in an elimination reaction and the formation of the η³-s-pentadienyl complex [Mo{η³-exo-anti-CH₂CHCH(CHCH₂)}(CO)₂(η⁵-C₅H₅)], which was structurally identified by X-ray crystallography. Interestingly, oxidation of 6 with [Bu₄ⁿN][RuO₄]/morpholine-N-oxide affords the aldehyde complex, 4 in good yield. Finally, reaction of 11 with [NO][BF₄] followed by addition of Na₂CO₃ affords the fur-3-ene complex [Mo{η²-

(H)Me}(CO)(NO)(η⁵-C₅H₅)].     

Structural variations in nickel, palladium, and platinum complexes containing pyrimidyl N-heterocyclic carbene ligand

Nickel(II), palladium(II), and platinum(II) complexes of 2-(3-mesitylimidazolylidenyl)pyrimidine (L), [Ni₂(μ-Cl)₂(L)₄][Ag₂Cl₄] (3), [Ni₂(μ-I)₂(L)₄][NiI(L)₂(CH₃CN)]₂[Ag₄I₈] (4), [PdCl₂(L)] (5), [PdI₂(L)] (6), and [PtCl(L)₂][AgCl₂] (7) have been obtained from the carbene transfer reactions of [Ag(L)Cl] (2). These complexes have been fully characterized by spectroscopic methods and single-crystal X-ray structure analyses. The mono(carbene)palladium and bis(carbene)platinum complexes display normal square–planar structures. Nickel complexes 3 and 4 are rare examples of paramagnetic nickel(II) complexes of N-heterocyclic carbenes having octahedral geometry.     

Ruthenium carbonyl clusters derived from pyrazolyl substituted diphosphazanes: Crystal and molecular structure of a triruthenium cluster featuring a triply bridging μ3-η1:η1:η1 coordination mode of pyrazolate moiety

The radical initiated reactions of Ru₃(CO)₁₂ with pyrazolyl substituted diphosphazanes Ph₂PN(R)PPh(N₂C₃HMe₂-3,5) [R = (S)-*CHMePh (1) or CHMe₂ (2)] proceed via P–N(pyrazole) bond rupture resulting in the formation of phosphido clusters, [Ru₃(CO)₅(μ_sb-CO)₂(μ₃-N,N′-η¹:η¹:η¹-N₂C₃HMe₂-3,5){μ-P,P′-Ph₂PN(R)PPh}] [R = (S)-*CHMePh (3) or CHMe₂ (4)]. The pyrazolate moiety adopts an unusual triply bridging μ₃-η¹:η¹:η¹-mode of coordination in these clusters.     

Triruthenium clusters containing mono and bidentate phosphines: Synthesis,structure, thermal reactivity and fluxional behavior

The syntheses, structures and thermal reactions of [Ru₃(CO)₉{P(C₄H₃E)₃}(μ-dppe)] (2, E = S; 3, E = O; dppe = 1,2-bis(diphenylphosphino)ethane) are described. These triphosphine-substituted clusters can be easily obtained in high yield from the Me₃NO initiated room temperature reaction between [Ru₃(CO)₁₀(μ-dppe)] (1) and P(C₄H₃E)₃. Both clusters have been structurally characterized which reveals that the functionalized phosphine P(C₄H₃E)₃ is coordinated to the remote ruthenium atom using the phosphorus atom, while the NMR spectroscopic data indicate that both clusters are fluxional in solution mainly due to the ring-flipping process involving the dppe ligand which has been probed by VT NMR spectroscopy. Thermolysis of 2 at 66 °C affords 1 via P(C₄H₃S)₃ dissociation, whilst that of 3 under similar experimental conditions also furnishes the diruthenium σ,π-furyl complex [Ru₂(CO)₆(μ,η²-C₄H₃O){μ-P(C₄H₃O)₂] (4) in addition to 1.     

Preparation of new dinuclear half-titanocene complexes with ortho- and meta-xylene linkages and investigation of styrene polymerization

Half-titanocene is well-known as an excellent catalyst for the preparation of SPS (syndiotactic polystyrene) when activated with methylaluminoxane (MAO). Dinuclear half-sandwich complexes of titanium bearing a xylene bridge, (TiCl₂L)₂{(μ-η⁵, η⁵-C₅H₄-ortho-(CH₂–C₆H₄–CH₂)C₅H₄}, (4 (L = Cl), 7 (L = O-2,6-iPr₂C₆H₃)) and (TiCl₂L)₂{(μ-η⁵, η⁵-C₅H₄-meta-(CH₂–C₆H₄–CH₂)C₅H₄} (5 (L = Cl), 8(L = O-2,6-iPr₂C₆H₃)), have been successfully synthesized and introduced for styrene polymerization. The catalysts were characterized by ¹H- and ¹³C NMR, and elemental analysis. These catalysts were found to be effective in forming SPS in combination with MAO. The activities of the catalysts with rigid ortho- and meta-xylene bridges were higher than those of catalysts with flexible pentamethylene bridges. The catalytic activity of four dinuclear half-titanocenes increased in the order of 4 < 5 < 7 < 8. This result displays that the meta-xylene bridged catalyst is more active than the ortho-xylene bridged and that the aryloxo group at the titanium center is more effective at promoting catalyst activity compared to the chloride group at the titanium center. Temperature and ratio of [Al]:[Ti] had significant effects on catalytic activity. Polymerizations were conducted at three different temperatures (25, 40, and 70 °C) with variation in the [Al]:[Ti] ratio from 2000 to 4000. It was observed that activity of the catalysts increased with increasing temperature, as well as higher [Al]:[Ti]. Different xylene linkage patterns (ortho and meta) were recognized to be a principal factor leading to the characteristics of the dinuclear catalyst due to its different spatial arrangement, causing dissimilar intramolecular interactions between the two active sites.     

Hydroformylation of oct-1-ene catalyzed by dinuclear gem-dithiolato-bridged rhodium(I) complexes and phosphorus donor ligands

The dinuclear gem-dithiolato bridged compounds [Rh₂(μ-S₂Cptn)(cod)₂] (1) (CptnS₂²⁻ = 1,1-cyclopentanedithiolato), [Rh₂(μ-S₂Chxn)(cod)₂] (2) (ChxnS₂²⁻ = 1,1-cyclohexanedithiolato), [Rh₂(μ-S₂CBn₂)(cod)₂] (3) (Bn₂CS₂²⁻ = 1,3-diphenyl-2,2-dithiolatopropane) and [Rh₂(μ-S₂CⁱPr₂)(cod)₂] (4) (ⁱPr₂CS₂²⁻ = 2,4-dimethyl-2,2-dithiolatopentane) dissolved in toluene in the presence of monodentate phosphine or phosphite P-donor ligands under carbon monoxide/hydrogen (1:1) atmosphere are efficient catalysts for the hydroformylation of oct-1-ene under mild conditions (6.8 atm of CO/H₂ and 80 °C). The influence of the gem-dithiolato ligand, the P-donor co-catalyst and the P/Rh ratio on the catalytic activity and selectivity has been explored. Aldehyde selectivities higher than 95% and turnover frequencies up to 245 h⁻¹ have been obtained using P(OMe)₃ as modifying ligand. Similar activity figures have been obtained using P(OPh)₃ although the selectivities are lower. Regioselectivities toward linear aldehyde are in the range 75–85%. The performance of the catalytic systems [Rh₂(μ-S₂CR₂)(CO)₂(PPh₃)₂]/PPh₃ has been found to be comparable to the systems [Rh₂(μ-S₂CR₂)(cod)₂] at the same P/Rh ratio. The system [Rh₂(μ-S₂CBn₂)(cod)₂] (3)/P(OPh)₃ has been tested in the hydroformylation-isomerization of trans-oct-2-ene. Under optimized conditions up to 54% nonanal was obtained. Spectroscopic studies under pressure (HPNMR and HPIR) evidenced the formation of hydrido mononuclear species under catalytic conditions that are most probably responsible for the observed catalytic activity.     

Preparation and characterization of diruthenium(II,III) compounds containing terminal olefin groups

4-Vinylbenzoic acid reacted with Ru₂(D(3,5-Cl₂Ph)F)₃(OAc)Cl and cis-Ru₂(D(3,5-Cl₂Ph)F)₂(OAc)₂Cl (D(3,5-Cl₂Ph)F is N,N′-bis(3,5-dichlorophenyl)formamidinate) to yield Ru₂(D(3,5-Cl₂Ph)F)₃(4-vinylbenzoate)Cl (1) and cis-Ru₂(D(3,5-Cl₂Ph)F)₂(4-vinylbenzoate)₂Cl (2), respectively. Ru₂(D(3,5-Cl₂Ph)F)₃(OAc)Cl reacted with 5-hexenoic acid and 6-heptenoic acid to afford Ru₂(D(3,5-Cl₂Ph)F)₃(5-hexenoate)Cl (3) and Ru₂(D(3,5-Cl₂Ph)F)₃(6-heptenoate)Cl (4), respectively. All new compounds were characterized using voltammetric and Vis–NIR spectroscopic techniques, and the structures of 1 and 2 were also established through X-ray single crystal diffractions.     

Dppm-substituted ruthenium clusters with capping sulfido and selenido ligands derived from thiourea, tetramethylthiourea and elemental selenium

Treatment of [Ru₃(CO)₁₀(μ-dppm)] (4) [dppm = bis(diphenylphosphido)methane] with tetramethylthiourea at 66 °C gave the previously reported dihydrido triruthenium cluster [Ru₃(μ-H)₂(μ₃-S)(CO)₇(μ-dppm)] (5) and the new compounds [Ru₃(μ₃-S)₂(CO)₇(μ-dppm)] (6), [Ru₃(μ₃-S)(CO)₇(μ₃-CO)(μ-dppm)] (7) and [Ru₃(μ₃-S){η¹-C(NMe₂)₂}(CO)₆(μ₃-CO)(μ-dppm)] (8) in 6%, 10%, 32% and 9% yields, respectively. Treatment of 4 with thiourea at the same temperature gave 5 and 7 in 30% and 10% yields, respectively. Compound 7 reacts further with tetramethylthiourea at 66 °C to yield 6 (30%) and a new compound [Ru₃(μ₃-S)₂{η¹-C(NMe₂)₂}(CO)₆(μ-dppm)] (9) (8%). Thermolysis of 8 in refluxing THF yields 7 in 55% yield. The reaction of 4 with selenium at 66 °C yields the new compounds [Ru₃(μ₃-Se)(CO)₇(μ₃-CO)(μ-dppm)] (10) and [Ru₃(μ₃-Se)(μ₃-η³-PhPCH₂PPh(C₆H₄)}(CO)₆(μ-CO)] (11) and the known compounds [Ru₃(μ-H)₂(μ₃-Se)(CO)₇(μ-dppm)] (12) and [Ru₄(μ₃-Se)₄(CO)₁₀(μ-dppm)] (13) in 29%, 5%, 2% and 5% yields, respectively. Treatment of 10 with tetramethylthiourea at 66 °C gives the mixed sulfur-selenium compounds [Ru₃(μ₃-S)(μ₃-Se)(CO)₇(μ-dppm)] (14) and [Ru₃(μ₃-S)(μ₃-Se){η¹-C(NMe₂)₂}(CO)₆(μ-dppm)] (15) in 38% and 10% yields, respectively. The single-crystal XRD structures of 6, 7, 8, 10, 14 and 15 are reported.     

Synthesis,Characterization and Crystal Structures of New Ruthenium Carbonyl Clusters Derived from (9-Anthracenyl)diphenylphosphine*

Thermal reaction of [Ru₂(CO)₆(μ-PFu₂)(μ-η¹,η²-Fu)] (Fu=2-furyl) with (9-anthracenyl)diphenylphosphine (AnPPh₂) produces a novel diruthenium complex [Ru₂(CO)₅(μ-PFu₂)(μ-η¹,η¹,η²-C₁₄H₈PPh₂)] (1) in good yield whereas the corresponding reaction between [(μ-H)₄Ru₄(CO)₁₂] and AnPPh₂ gives [HRu(CO)₃(PPh₂C₁₄H₈)][(μ-H)₄Ru₄(CO)₁₁(AnPPh₂)] (2). Both compounds 1 and 2 were fully characterized by spectroscopic methods and their X-ray crystal structures were determined. For 1, initial coordination of the PPh₂ functionality at the Ru atom is accompanied by cyclometalation of the anthracenyl ring to form a Ru–C σ bond together with concomitant formation of a π bond to the adjacent Ru center and loss of the furyl ligand. The formation of 2 involves the cleavage of two Ru–Ru bonds, and the making of a Ru–P bond, followed by orthometalation of the anthracenyl ring. The optical absorption and emission spectra of 1 were recorded and the results were correlated to the DFT calculations.Dedicated to Professor F. Albert Cotton on the occasion of his 75th birthday.     

Thermal and photochemical transformations of 2-methylthiothiophene in triosmium clusters: photoinduced migrations of MeS from carbon to metal and back again

2-Methylthiothiophene (2-MeSC₄H₃S) oxidatively adds to [Os₃(CO)₁₀(MeCN)₂] with cleavage of the C–H bond at the 3-position to give [Os₃(μ-H)(μ-MeSC₄H₂S)(CO)₁₀] 1, the X-ray structure of which shows that the MeS group is coordinated to osmium through the S atom while the thiophene ring is coordinated to osmium through the 3-carbon atom. Only one invertomer at sulfur is observed in solution and in the crystal the Me group is exo. Thermal treatment of 1 in the dark gives only one product, [Os₃(μ-H)(μ₃-MeSC₄H₂S)(CO)₉] 2 (X-ray structure), derived by loss of a CO from the Os(CO)₄ unit of 1 with concomitant η²-coordination of the thiophene ring of bridging MeSC₄H₂S at the third metal atom. Whereas thermal reaction in the dark leads only to C–H cleavage products, visible irradiation at room temperature leads to various products derived by migration of the MeS group. Thus thermal treatment of 1 in daylight for 2 h gave 2, together with an isomer 3. Cluster 2 converts at room temperature to 3 in daylight while thermal treatment of 2 in the dark (125°C) gave no reaction. Isomer 3 of [Os₃(μ-H)(μ₃-MeSC₄H₂S)(CO)₉] (X-ray structure) is closely related to 2 except that the MeS group and the Os–C σ-bond have interchanged sites at the thiophene ring between the 2- and the 3-positions. Visible irradiation of 1 at room temperature for 3 days in daylight gave further chemical change leading to two bridging thienyl clusters, [Os₃(μ-MeS)(μ-2-C₄H₂S)(CO)₁₀] 4 and [Os₃(μ-MeS)(μ₃-2-C₄H₂S)(CO)₉] 5. Cluster 5 is the ultimate product of daylight irradiation of any of the clusters 1 to 4.     

Studies on the reactivity of the clusters [Ru3(CO)8(μ-H)2(μ-PR2)2] (R=But,Cy) towards phosphine ligands

The reaction behavior of the 48e-clusters [Ru₃(CO)₈(μ-H)₂(μ-PR₂)₂] (R=Bu^t, 1a; R=Cy, 1b) towards phosphine ligands has been studied. Whereas 1a reacts spontaneously with many phosphines at room temperature, a lack of reactivity for 1b under similar conditions is observed. Thus 1a reacts with dppm (Ph₂PCH₂PPh₂) to the known 46e-cluster [Ru₃(μ-CO)(CO)₄(μ₃-H)(μ-H)(μ-PBu^t₂)₂(μ-dppm)] (2a), and the reaction of 1a with dppe (Ph₂PC₂H₄PPh₂) yields analogously [Ru₃(μ-CO)(CO)₄(μ₃-H)(μ-H)(μ-PBu^t₂)₂(μ-dppe)] (3). Reactions of 1a with dmpm (Me₂PCH₂PMe₂), dmpe (Me₂PC₂H₄PMe₂) and PBuⁿ₃, respectively, gave in each case a mixture of products which could not be characterized. Contrary to the reaction behavior at room temperature, 1b reacts with phosphines in THF under reflux yielding the novel complexes [Ru₃(CO)₆(μ-H)₂(μ-PCy₂)₂L₂] (L=Cy₂PH, 4a; L=Bu^t₂PH, 4b; L=Ph₂PH, 4c; L=P(OEt)₃, 4d). 4a is also obtained directly by the reaction of [Ru₃(CO)₁₂] with an excess of Cy₂PH. The molecular structure of 4a has been determined by a single-crystal X-ray analysis. Moreover, the thermolysis of 1a in octane affords [Ru₃(CO)₈(μ-H)₂(μ₃-PBu^t)(Bu^t₂PH)] (6) as the main product, and the thermolysis of [Ru₃(CO)₉(Bu^t₂PH)(μ-dppm)] (7) yields 2a to a considerable extent. Treatment of 1a with carbon tetrachloride leads to [Ru₃(CO)₇(μ-H)(μ-PBu^t₂)₂(μ-Cl)] (8) as the main product.     

Synthesis and structural characterization of mesitylphosphinidene-capped ruthenium and osmium clusters

Thermal reaction of [Ru₃(CO)₁₂] with PH₂Mes (Mes = mesityl) in refluxing toluene afforded mesitylphosphinidene-capped ruthenium carbonyl clusters, [Ru₃(CO)₉(μ-H)₂(μ₃-PMes)] (1), [Ru₃(CO)₈(PH₂Mes)(μ-H)₂(μ₃-PMes)] (2), [Ru₃(CO)₉(μ₃-PMes)₂] (3), [Ru₄(CO)₁₀(μ-CO)(μ₄-PMes)₂] (4), and [Ru₅(CO)₁₀H₂(μ₄-PMes)(μ₃-PMes)₂] (5). All products were fully characterized and structurally confirmed by X-ray crystal structure analysis. Complexes 2-4 were also obtained in high yields by stepwise reaction starting from 1. Fluxional behavior of carbonyl groups was observed in case of 4. Complex 5 reveals a new type of skeletal structure, bicapped-octahedron having μ₃- and μ₄-phosphinidene ligands at the capping positions. Similar reaction of [Os₃(CO)₁₂] with PH₂Mes yielded a phosphido-bridged osmium cluster [Os₃(CO)₁₀(μ-H)(μ-PHMes)] (6) and a phosphinidene-capped cluster [Os₃(CO)₉(μ-H)₂(μ₃-PMes)] (7).     

Synthesis and structure of sulfur and selenium capped dihydride triruthenium clusters [Ru3(CO)7(μ-H)2(μ-dppm)(μ3-E)] (E = S, Se)

Reaction of [Ru₃(CO)₁₀(μ-dppm)] (1) with H₂S at 66 °C affords high yields of the sulfur-capped dihydride [Ru₃(CO)₇(μ-H)₂(μ-dppm)(μ₃-S)] (2), formed by oxidative-addition of both hydrogen-sulfur bonds. Hydrogenation of [Ru₃(CO)₇(μ-dppm)(μ₃-CO)(μ₃-S)] (3) at 110 °C also gives 2 in similar yields, while hydrogenation of [Ru₃(CO)₇(μ-dppm)(μ₃-CO)(μ₃-Se)] (4) affords [Ru₃(CO)₇(μ-H)₂(μ-dppm)(μ₃-Se)] (5) in 85% yield. The molecular structures of 2 and 5 reveal that the diphosphine and one hydride simultaneously bridge the same ruthenium-ruthenium edge with the second hydride spanning one of the non-bridged edges. Both 2 and 5 are fluxional at room temperature being attributed to hydride migration between the non-bridged edges. Addition of HBF₄ to 2 affords the cationic trihydride [Ru₃(CO)₇(μ-H)₃(μ-dppm)(μ₃-S)][BF₄] (6) in which the hydrides are non-fluxional due to the blocking of the free ruthenium-ruthenium edge.     

Transition metal complexes with thiosemicarbazide-based ligands. Part 56. Square-pyramidal complexes of copper(II) with 2-acetylpyridine S-methylisothiosemicarbazone

The article describes the synthesis and single-crystal X-ray analysis of two sulfato and one thiocyanato copper(II) complex with 2-acetylpyridine S-methylisothiosemicarbazone (HL) of the formulae [Cu(HL)SO₄(H₂O)]·H₂O (1), [Cu₂(HL)₂(μ-SO₄)₂]·2H₂O (2) and [Cu(HL)(NCS)(SCN)] (3), as well as the structure of the protonated ligand H₂L⁺I⁻. Complexes 1 and 2 were obtained from the reaction of aqueous/methanolic CuSO₄·5H₂O and ethanolic/methanolic H₂L⁺I⁻ solutions, respectively. Complex 3 was synthesized by the reaction of methanolic solutions of Cu(ClO₄)₂·6H₂O, the ligand and NH₄SCN, with the addition of triethyl orthoformate. All three complexes have a slightly deformed square-pyramidal structure (τ_av = 0.15) with the tridentate NNN neutral ligand in the basal plane. In complexes 1 and 3 the apical position is occupied by the oxygen atom of the monodentate SO₄ group, or the sulfur atom of the SCN group. Thanks to the hydrogen bonds, complex 3 may be thought of as having a pseudo-dimeric structure. In the authentic centrosymmetric dimer 2, the oxygen atoms of both SO₄ groups occupy also the apical position of both coordination polyhedra, as well as an equatorial position. Complexes 1 and 3 have μ_eff values characteristic of magnetically isolated mononuclear Cu(II) complexes. In contrast to them, complex 2 has a μ_eff value of 1.57 BM, which is in agreement with its dinuclear structure. All the complexes, in addition to the X-ray analysis and magnetic measurements, were characterized by IR and UV–Vis spectroscopy and by thermal analysis.     

Multinuclear NMR studies on substituted derivatives of Rh6(CO)16 in solution

Multinuclear NMR data (¹³C, ³¹P, ¹³C–{³¹P}, ¹³C–{¹⁰³Rh} and ³¹P–{¹⁰³Rh}) for a series of mono- and di-substituted derivatives of Rh₆(CO)₁₆ containing neutral two electron donor ligands [Rh₆(CO)₁₅L, (L=NCMe, py, cyclooctene, PPh₃, P(OPh)₃,1/2(μ₂,η¹:η¹-dppe)); Rh₆(CO)₁₄(LL), (LL=cis-CH₂=CMe-CMe=CH₂, dppm, dppe, (P(OPh)₃)₂)] are reported; these data show that the solid state structure is maintained in solution. Detailed assignments of the ¹³CO NMR spectra of Rh₆(CO)₁₅(PPh₃) and Rh₆(CO)₁₄(dppm) clusters have been made on the basis ¹³C–{¹⁰³Rh} double resonance measurements and the specific stereochemical features of the observed long range couplings in these clusters have been studied. The stereochemical dependence of ³J(P–C) for terminal carbonyl ligands is discussed and the values of ³J(P–C) are found to be mainly dependent on the bond angles in the P–Rh–Rh–C fragment; these data enable the fine structure of the complex multiplets in the ¹³C–{¹H} and ³¹P–{¹H} NMR spectra of Rh₆(CO)₁₄ (dppm) to be simulated. Variable temperature ¹³C–{¹H} NMR measurements on Rh₆(CO)₁₅(PPh₃) reveal the carbonyl ligands in this complex to be fluxional. The fluxional process involves exchange of all the CO ligands except the two terminal CO's associated with the rhodium trans to the substituted rhodium and can be explained by a simple oscillation of the PPh₃ on the substituted rhodium atom aided by concomitant exchange of the unique terminal CO on this rhodium with adjacent μ₃-CO's.