Influence of chain length on mono- versus di-alkylation in the reactivity of [Pt2(μ-S)2(PPh3)4] towards α,ω-dihalo-n-alkanes; a synthetic route to platinum(II) ω-haloalkylthiolate complexes

The reactions of [Pt₂(μ-S)₂(PPh₃)₄] with α,ω-dibromoalkanes Br(CH₂)_nBr (n = 4, 5, 6, 8, 12) gave mono-alkylated [Pt₂(μ-S){μ-S(CH₂)_nBr}(PPh₃)₄]⁺ and/or di-alkylated [Pt₂(μ-S(CH₂)_nS}(PPh₃)₄]²⁺ products, depending on the alkyl chain length and the reaction conditions. With longer chains (n = 8, 12), intramolecular di-alkylation does not proceed in refluxing methanol, with the mono-alkylated products [Pt₂(μ-S){μ-S(CH₂)_nBr}(PPh₃)₄]⁺ being the dominant products when excess alkylating agent is used. The bridged complex [{Pt₂(μ-S)₂(PPh₃)₄}₂{μ-(CH₂)₁₂}]²⁺ was accessible from the reaction of [Pt₂(μ-S)₂(PPh₃)₄] with 0.5 mol equivalents of Br(CH₂)₁₂Br. [Pt₂(μ-S){μ-S(CH₂)₄Br}(PPh₃)₄]⁺ can be cleanly isolated as its BPh₄⁻ salt, but undergoes facile intramolecular di-alkylation at −18 °C, giving the known species [Pt₂(μ-S(CH₂)₄S}(PPh₃)₄]²⁺. The reaction of I(CH₂)₆I with [Pt₂(μ-S)₂(PPh₃)₄] similarly gives [Pt₂(μ-S){μ-S(CH₂)₆I}(PPh₃)₄]⁺, which is fairly stable towards intramolecular di-alkylation once isolated. These reactions provide a facile route to ω-haloalkylthiolate complexes which are poorly defined in the literature. X-ray crystal structures of [Pt₂(μ-S){μ-S(CH₂)₅Br}(PPh₃)₄]BPh₄ and [Pt₂(μ-S(CH₂)₅S}(PPh₃)₄](BPh₄)₂ are reported, together with a study of these complexes by electrospray ionisation mass spectrometry. All complexes fragment by dissociation of PPh₃ ligands, and the bromoalkylthiolate complexes show additional fragment ions [Pt₂(μ-S){μ-S(CH₂)_n−2CHCH₂}(PPh₃)_m]⁺ (m = 2 or 3; m ≠ 4), most significant for n = 4, formed by elimination of HBr.     

Single and double nucleophilic attack on cluster-bonded allenylidenes: Synthesis of phosphorus heterocycles

Further studies of the attack of bidentate tertiary phosphines, such as dppm and dppe, and the related diarsine dpam, on Ru₃(μ-H){μ₃-C₂CHR(OH)}(CO)₉ (R = H, Me) are described, together with the X-ray determined structures of [Ru₃(μ₃-C₂CH₂PPh₂CH₂CH₂PPh₂)(CO)₉]BF₄ (6) and Ru₃(μ-H){μ₃-C₂CHMePPh₂CHPPh₂}(CO)₉ (7) (containing diphospha heterocycles), Ru₃(μ-H){μ₃-CH₂(OH)C₂PPh₂CH₂PPh₂}(CO)₈ (8) (containing a phosphonium-alkynyl ligand also coordinated to a cluster Ru atom) and Ru₃(μ-H)(μ₃-CCCHAsPh₂CH₂AsPh₂)(CO)₉ (9) (containing an arsino-allenylidene ligand). These complexes are formed by nucleophilic attack of the Group 15 ligand on an alkynyl or allenylidene ligand on the cluster.     

Kinetic studies on the reactions of HCl with trans-[MoL(CNPh)(Ph2PCH2CH2PPh2)2] (L=N2, H2 or CO)

The kinetics of the reactions between anhydrous HCl and trans-[MoL(CNPh)(Ph₂PCH₂CH₂PPh₂)₂] (L=CO, N₂ or H₂) have been studied in thf at 25.0 °C. When L=CO, the product is [MoH(CO)(CNPh)(Ph₂PCH₂CH₂PPh₂)₂]⁺, and when L=H₂ or N₂ the product is trans-[MoCl(CNHPh)(Ph₂PCH₂CH₂PPh₂)₂]. Using stopped-flow spectrophotometry reveals that the protonation chemistry of trans-[MoL(CNPh)(Ph₂PCH₂CH₂PPh₂)₂] is complicated. It is proposed that in all cases protonation occurs initially at the nitrogen atom of the isonitrile ligand to form trans-[MoL(CNHPh)(Ph₂PCH₂CH₂PPh₂)₂]⁺. Only when L=N₂ is this single protonation sufficient to labilise L to dissociation, and subsequent binding of Cl⁻ gives trans-[MoCl(CNHPh)(Ph₂PCH₂CH₂PPh₂)₂]. At high concentrations of HCl a second protonation occurs which inhibits the substitution. It is proposed that this second proton binds to the dinitrogen ligand. When L=CO or H₂, a second protonation is also observed but in these cases the second protonation is proposed to occur at the carbon atom of the aminocarbyne ligand, generating trans-[MoL(CHNHPh)(Ph₂PCH₂CH₂PPh₂)₂]²⁺. Addition of the second proton labilises the trans-H₂ to dissociation, and subsequent rapid binding of Cl⁻ and dissociation of a proton yields the product trans-[MoCl(CNHPh)(Ph₂PCH₂CH₂PPh₂)₂]. Dissociation of L=CO does not occur from trans-[Mo(CO)(CHNHPh)(Ph₂PCH₂CH₂PPh₂)₂]²⁺, but rather migration of the proton from carbon to molybdenum, and dissociation of the other proton produces [MoH(CO)(CNPh)(Ph₂PCH₂CH₂PPh₂)₂]⁺.     

Heteroligand copper(I) complexes of N-thiophosphorylated thioureas and phosphanes: Versatile structures and luminescence

Reaction of the potassium salts of (EtO)₂P(O)CH₂C₆H₄-4-(NHC(S)NHP(S)(OiPr)₂) (HL^I), (CH₂NHC(S)NHP(S)(OiPr)₂)₂ (H₂L^II) or cyclam(C(S)NHP(S)(OiPr)₂)₄ (H₄L^III) with [Cu(PPh₃)₃I] or a mixture of CuI and Ph₂P(CH₂)_1-3PPh₂ or Ph₂P(C₅H₄FeC₅H₄)PPh₂ in aqueous EtOH/CH₂Cl₂ leads to [Cu(PPh₃)L^I] (1), [Cu₂(Ph₂PCH₂PPh₂)₂L^II] (2), [Cu{Ph₂P(CH₂)₂PPh₂}L^I] (3), [Cu{Ph₂P(CH₂)₃PPh₂}L^I] (4), [Cu{Ph₂P(C₅H₄FeC₅H₄)PPh₂}L^I] (5), [Cu₂(PPh₃)₂L^II] (6), [Cu₂(Ph₂PCH₂PPh₂)L^II] (7), [Cu₂{Ph₂P(CH₂)₂PPh₂}₂L^II] (8), [Cu₂{Ph₂P(CH₂)₃PPh₂}₂L^II] (9), [Cu₂{Ph₂P(C₅H₄FeC₅H₄)PPh₂}₂L^II] (10), [Cu₈(Ph₂PCH₂PPh₂)₈L^IIII₄] (11), [Cu₄{Ph₂P(CH₂)₂PPh₂}₄L^III] (12), [Cu₄{Ph₂P(CH₂)₃PPh₂}₄L^III] (13) or [Cu₄{Ph₂P(C₅H₄FeC₅H₄)PPh₂}₄L^III] (14) complexes. The structures of these compounds were investigated by IR, ¹H, ³¹P{¹H} NMR spectroscopy; their compositions were examined by microanalysis. The luminescent properties of the complexes 1-14 in the solid state are reported.     

Coordination chemistry of higher oxidation states. Part 15. Cobalt(III) complexes of bi- and multi-dentate phenylphosphines

Six-coordinate cobalt(III) complex trans-[Co{o-C₆H₄(PPh₂)₂}₂X₂]ClO₄, fac-[Co{PhP(CH₂CH₂PPh₂)₂}X₃],cis-[Co{P(CH₂CH₂PPh₂)₃}X₂]ClO₄ and cis-β-[Co{-CH₂P(Ph)CH₂CH₂PPh₂}₂X₂]PF₆ (X = Cl, Br) have been prepared by halogen oxidation of the Co(II) analogues, and characterised by IR, electronic and ³¹P NMR spectroscopy. The failure to obtain complexes with X = I, and with some related ligands is discussed, and the rather low stability of the above complexes is rationalised in terms of steric crowding at the metal centre.     

Rhenium(III) and rhenium(V) complexes stabilized by the potentially tetradentate ligand tris(2-diphenylphosphinoethyl)amine

The reaction of the rhenium(V) nitrido complex [Re(N)Cl₂(PPh₃)₂] with the tripodal ligand N(CH₂CH₂PPh₂)₃ (NP₃) in THF gave [Re(N)Cl₂(η²-P,P-NP₃)] (1) in which NP₃ acts as a tridentate ligand using the nitrogen and two phosphorus donors for coordination. Refluxing 1 in a polar solvent such as ethanol produced [(η⁴-NP₃)Re(N)Cl]Cl (2) in which NP₃ acts as a tetradentate ligand. Treatment of complex [Re(O)Cl₃(AsPh₃)₂] containing the [ReO]³⁺ core with NP₃ in THF yielded [ReCl₃{η³-N,P,P-(N{CH₂CH₂Ph₂}₂{CH₂CH₂P(O)Ph₂})}] (3). Complexes 1 and 3 have been characterized by single-crystal X-ray analyses.     

Synthesis and X-ray structures of rhenium(I) carbonyl aminoalkoxide and aminocarboxylate complexes

The complexes [Re{MeN(CH₂CH₂O)(CH₂CH₂OH)-κ³N,O,O}(CO)₃] (1), [Re{N(CH₂CH₂O)(CH₂CH₂OH)₂-κ³N,O,O}(CO)₃] (2), [Me₃NH]₂[(OC)₃Re{N(CH₂CO₂)₂-κ³N,O,O}CH₂CH₂{N(CH₂CO₂)₂-κ³N,O,O}Re(CO)₃] (3), [Me₃NH]₂[Re₂{μ₂-2,6-(O₂C)₂(C₅H₃N)-κ³N,O,O}₂(CO)₆] (4) and [Re₂{μ₂-2,6-(OCH₂)(C₅H₃N)(CH₂OH)-κ²N,O}₂(CO)₆] (5) were synthesized in high yields via the reactions of [Re₂(CO)₁₀] and Me₃NO with MeN(CH₂CH₂OH)₂, N(CH₂CH₂OH)₃, EDTA, pyridine-2,6-dicarboxylic acid and pyridine-2,6-dimethanol, respectively. Complexes 1-5 were characterized by IR and ¹H NMR spectroscopy, elemental analysis and X-ray crystallography.     

New synthesis of seven-coordinate complexes of molybdenum(II) and tungsten(II) containing bidentate phosphorus ligands, [MI2(CO)3{Ph2P(CH2)nPPh2}] (n = 1–6)

A new high yielding synthesis of the seven-coordinate complexes [MI₂(CO)₃{Ph₂P(CH₂)_nPPh₂}] (M = Mo and W; n = 1–6) is described. The procedure involves reacting the complexes [MI₂(CO)₃(NCMe)₂] in CH₂Cl₂ with an equimolar amount of the bidentate phosphorus ligand. The low temperature (−70 °C) ¹³C NMR spectra of the complexes [Wl₂(CO)₃{Ph₂P(CH₂)_nPPh₂}] (n = 3 and 5) indicates that the geometry is capped octahedral with a carbonyl ligand in the unique capping position.     

Quantifying the electronic cis effect of phosphine, arsine and stibine ligands by use of rhodium(I) Vaska-type complexes

The cis effects of phosphine, arsine and stibine ligands have been evaluated by measuring the IR stretching frequency in dichloromethane of the carbonyl ligand in a series of Rh(I) Vaska-type complexes, trans-[RhCl(CO)(L)₂]. These data were correlated with those obtained by Tolman for the electronic trans influences in the [Ni(L)(CO)₃] complexes. The electronic contribution, χ_Fc, of ferrocenyl was determined as 0.8 from these plots by evaluating PPh₂Fc as ligand. In order to accommodate arsine and stibine ligands an additional correction term, to compensate for differences in the donor atom, was added to Tolman’s equation for calculation of the Tolman electronic parameter of phosphine ligands. In the resulting equation: ν(CO_Ni)=2056.1+∑_i=1³χ_i+C_L values for C_L of C_P=0, C_As=−1.5 and C_Sb=−3.1 are suggested for phosphine, arsine and stibine ligands, respectively. The crystal and molecular structures of trans-[RhCl(CO)(PPh₂Fc)₂] · 2C₆H₆, trans-[RhCl(CO){P(NMe₂)₃}₂] and trans-[RhCl(CO)(AsPh₃)₂] are reported. The Tolman cone angles for PPh₂Fc and P(NMe₂)₃ were determined as 169° and 166°, while the effective cone angles for PPh₂Fc, P(NMe₂)₃ and AsPh₃ were determined as 171°, 168° and 147°, respectively.     

Dinuclear ruthenium complexes containing tripodal dithiophosphonate ligands

Treatment of [(η⁶-p-cymene)RuCl(μ-Cl)]₂ with Lawesson’s reagent [ArP(S)(μ-S)]₂ (Ar = p-C₆H₄OMe) in the presence of ammonium hydroxide afforded the dinuclear complex [(η⁶-p-cymene)Ru{μ-η¹(S),η²(S,S′)-ArP(O)S₂}]₂ (1) in which the tripodal [ArP(O)S₂]²⁻ ligands bind to the ruthenium atom in both bridging and chelating modes with two non-coordinating PO groups. Interaction of [RuHCl(CO)(PPh₃)₃] with [ArP(S)(μ-S)]₂ and bis(diphenylphosphino)methane (dppm) in the presence of ammonium hydroxide gave the dinuclear complex [Ru(CO){μ₃-η¹(O),η²(S,S′)-ArP(O)S₂}(dppm)]₂ (2) in which the tripodal [ArPOS₂]²⁻ ligands bind the two Ru atoms via both sulfur and oxygen atoms. Treatment of [Ru(PPh₃)₃Cl₂] with [ArP(S)(μ-S)]₂ at reflux in the presence of ammonium hydroxide led to the formation of the dinuclear mixed valence complex [Ru₂Cl₂(μ-S){μ₃-η¹(O),η¹(S),-η²(S,S′)-ArP(O)S₂}(PPh₃)₃] (3), which contains a [Ru^II(PPh₃)₂Cl]⁺ and [Ru^IV(PPh₃)Cl]³⁺ moieties by the tripodal [ArPOS₂]²⁻ ligand in a μ₃-η¹(O),η¹(S),η²(S,S′) coordination mode and the μ-S²⁻ anion. The crystal structures of 1, 2, and 3·CH₂Cl₂ along with their spectroscopic and electrochemical properties are reported.     

Studies on the reactions of ruthenium(II) substrates with tridentate (N,N,O) azo ligands

Reactions of 1-{[2-(arylazo)phenyl]iminomethyl}-2-phenol, HL_sal, 1, [where H represents the dissociable protons upon complexation and aryl groups of HL_sal are phenyl for HL¹_sal, p-methylphenyl for HL²_sal, and p-chlorophenyl for HL³_sal], ligands with Ru(H)(CO)(Cl)(PPh₃)₃ afforded complexes of composition [(L_sal)Ru(CO)(Cl)(PPh₃)] and (L_sal)₂Ru where the N,N,O donor tridentate (L_sal)⁻ ligands coordinated the metal centre facially and meridionally, respectively. Stepwise formation of [(L_sal)₂Ru] has been ascertained. Reaction of 1-{[2-(arylazo)phenyl]iminomethyl}-2-napthol, HL_nap, 2, [where H represents the dissociable protons upon complexation and aryl groups of HL_nap are phenyl for HL¹_nap, p-methylphenyl for HL²_nap, and p-chlorophenyl for HL³_nap], ligands with Ru(H)(CO)(Cl)(PPh₃)₃ afforded exclusively the complexes of composition [(L_nap)Ru(CO)(Cl)(PPh₃)], where N,N,O donor tridentate (L_nap)⁻ was facially coordinated. The ligand 1-{[2-(phenylazo)phenyl]aminomethyl}-2-phenol, HL, 3, was prepared by reducing the aldimine function of HL¹_sal. Reaction of HL with Ru(PPh₃)₃Cl₂ afforded new azosalen complex of Ru(III) in concert with regiospecific oxygenation of phenyl ring of HL. All the new ligands were characterized by analytical and spectroscopic techniques. The complexes were characterized by analytical and spectroscopic techniques and subsequently confirmed by the determination of X-ray structures of selected complexes.     

Ruthenium hydride and vinyl complexes supported by nitrogen-oxygen mixed-donor ligands

The Schiff base, 2-chlorophenylsalicylaldimine (HL₁), is formed readily from salicylaldehyde and 2-chloroaniline. After deprotonation, this ligand is found to react as a bidentate mixed-donor chelate with the complexes [RuRCl(CO)(BTD)(PPh₃)₂] (R = H, CHCHC₆H₅, CHCHC₆H₄Me-4, CHCH^tBu, CCCPhCHPh; BTD = 2,1,3-benzothiadiazole) to form the compounds [RuR(L₁)(CO)(PPh₃)₂] through displacement of the chloride and BTD ligands. An analogous reaction occurs with the osmium complex [OsHCl(CO)(BTD)(PPh₃)₂] to provide [OsH(L₁)(CO)(PPh₃)₂]. The compound [Ru(CHCHC₆H₄Me-4)(L₂)(CO)(PPh₃)₂] is formed through reaction of salicylaldehyde (HL₂) with [Ru(CHCHC₆H₄Me-4)Cl(CO)(BTD)(PPh₃)₂] in the presence of base. Two further ligands were investigated to extend the study to encompass 5- and 4-membered chelates; 8-hydroxyquinoline (HL₃) and 2-hydroxy-4-methylquinoline (HL₄) react with [Ru(CHCHPh)Cl(CO)(BTD)(PPh₃)₂] and [Ru(CHCHC₆H₄Me-4)Cl(CO)(BTD)(PPh₃)₂] in the presence of base to yield the complexes [Ru(CHCHPh)(L₃)(CO)(PPh₃)₂] and [Ru(CHCHC₆H₄Me-4)(L₄)(CO)(PPh₃)₂], respectively. The crystal structure of [Ru(CHCHC₆H₄Me-4)(L₁)(CO)(PPh₃)₂] is reported.     

Further studies on the dialkylation chemistry of [Pt2(μ-S)2(PPh3)4] with activated alkyl halides RC(O)CH2X (X = Cl, Br)

Further studies have been carried out into the reactivity of [Pt₂(μ-S)₂(PPh₃)₄] towards a range of activated alkylating agents of the type RC(O)CH₂X (R = organic moiety, e.g. phenyl, pyrenyl; X = Cl, Br). Alkylation of both sulfide centers is observed for PhC(O)CH₂Br, 3-(bromoacetyl)coumarin [CouC(O)CH₂Br], and 1-(bromoacetyl)pyrene [PyrC(O)CH₂Br], giving dications [Pt₂{μ-SCH₂C(O)R}₂(PPh₃)₄]²⁺, isolated as their PF₆⁻ salts. The X-ray structure of [Pt₂{μ-SCH₂C(O)Ph}₂(PPh₃)₄](PF₆)₂ shows the presence of short Pt?O contacts. In contrast, the corresponding chloro compounds [typified by PhC(O)CH₂Cl] and imino analogues [e.g. PhC(NOH)CH₂Br] do not dialkylate [Pt₂(μ-S)₂(PPh₃)₄]. The ability of PhC(O)CH₂Br to dialkylate [Pt₂(μ-S)₂(PPh₃)₄] allows the synthesis of new mixed-alkyl dithiolate derivatives of the type [Pt₂{μ-SCH₂C(O)Ph}(μ-SR)(PPh₃)₄]²⁺ (R = Et or n-Bu), through alkylation of in situ-generated monoalkylated compounds [Pt₂(μ-S)(μ-SR)(PPh₃)₄]⁺ (from [Pt₂(μ-S)₂(PPh₃)₄] and excess RBr). In these heterodialkylated systems ligand replacement of PPh₃ occurs by the bromide ions in the reaction mixture forming monocations [Pt₂{μ-SCH₂C(O)Ph}(μ-SR)(PPh₃)₃Br]⁺. This ligand substitution can be easily suppressed by addition of PPh₃ to the reaction mixture. The complex [Pt₂{μ-SCH₂C(O)Ph}(μ-SBu)(PPh₃)₄]²⁺ was crystallographically characterized. X-ray crystal structures of the bromide-containing complexes [Pt₂{μ-SCH₂C(O)Ph}(μ-SR)(PPh₃)₃Br]⁺ (R = Et, Bu) are also reported. In both structures the coordinated bromide is trans to the SCH₂C(O)Ph ligand, which adopts an axial position, while the ethyl and butyl substituents adopt equatorial positions, in contrast to the structures of the dialkylated complexes [Pt₂{μ-SCH₂C(O)Ph}₂(PPh₃)₄]²⁺ and [Pt₂{μ-SCH₂C(O)Ph}(μ-SBu)(PPh₃)₄]²⁺ (and many other known analogues) where both alkyl groups adopt axial positions.     

Transition metal complexes with sulfur ligands. XIX. Mono- and bis-alkylation of [Ru(II)L1L2dttd] complexes controlled by the ligands L as well as the charge of the resulting compounds (dttd2−=2,3:8,9-dibenzo-1,4,7,10-tetrathiadecane(−2), L1L2PPh3; L1L2PMe3; L1PPh3, L2PMe3)

The alkylation of the thiolato-S atoms of the dttd- ligand in [RuL₁L₂dttd] complexes was investigated (L₁L₂PPh₃; L₁L₂PMe₃; L₁PPh₃, L₂PMe₃; dttd²⁻=2,3:8,9-dibenzo-1,4,7,10-tetrathiadecane(−2)). The substitution lability of the phosphine ligands L₁ and L₂ determines whether one or both of the thiolato-S atoms are alkylated when [RuL₁L₂dttd] is reacted with alkylhalides. [Ru(PPh₃)₂dttd], in which one PPh₃ is substitution labile, is doubly alkylated on reaction with CH₃I yielding [Ru(PPh₃)I(Me₂-dttd)]I (Me₂-dttd=1,10-dimethyl-2,3:8,9-dibenzo-1,4,7,10-tetrathiadecane). Reaction of the substitution inert phosphine complexes [Ru(PMe₃)₂dttd] and [Ru(PPh₃)(PMe₃)dttd] with CH₃I yields the monoalkylated derivatives [Ru(PMe₃)₂(Me-dttd)]I and [Ru(PPh₃)(PMe₃)(Me- dttd)]I, respectively. Analogously, ethyl as well as bromine derivatives can be obtained. The cation in [Ru(PPh₃)X(Me₂-dttd)]X (XI, Br) proves to be substitution inert under ordinary conditions; the anion X can be exchanged for other singly charged anions via [Ru(PPh₃)X(Me₂dttd)]₂SO₄. In concentrated H₂SO₄, [Ru(PPh₃)Br(Me₂-dttd)]Br could be reacted to give [Ru(Br₂)(Me₂dttd)]. All compounds were characterized spectroscopically as well as by elemental analyses. The structure of [Ru(PPh₃)I(Me₂- dttd)]I was determined by X-ray structure analysis.[Ru(PPh₃)I(Me₂-dttd)]I (1) crystallizes from CH₂Cl₂ as 1·3CH₂Cl₂ in the monoclinic space group P2₁/c with the following unit cell dimensions: a= 20.103(0.03), b=11.148(0.009), c=26.985(0.03) Å; β=130.71(0.07)°, V=4584(3) ų and Z=4. The structure refinement stopped at R₁=8.86 and R₂= 10.44% because of disorder of the CH₂Cl₂ solvate molecules. In the cation of 1 Ru is coordinated pseudo-octahedrally by I-, P- and four thioether-S atoms.     

Coordination of 4-mercapto-1,2-dithiole-3-thione heterocycles to ruthenium(II) and molybdenum(VI) centres

Deprotonation of 4-mercapto-1,2-dithiole-3-thiones with NEt₃ followed by reaction with [Ru(H)(Cl)(CO)(PPh₃)₃] affords virtually quantitative yields of turquoise [Ru(H)(RC₃S₄)(CO)(PPh₃)₂] (R = Ph, Mes) in which the heterocycle is bound as a bidentate uninegative ligand through the two exocyclic sulfur atoms. The presence of both possible isomers in each case is indicated by NMR spectroscopy. Reaction of the 4-mercapto-1,2-dithiole-3-thiones with [MoO₂(acac)₂] results in displacement of the acac ligands and formation of [MoO₂(RC₃S₄)₂]. The crystal structures of [Ru(H)(MesC₃S₄)(CO)(PPh₃)₂] and [MoO₂(MesC₃S₄)₂] have been determined.     

‘Synthetic prospecting’ using an electrospray ionisation mass spectrometry directed survey of the alkylation and arylation chemistry of [Pt2(μ-S)2(PPh3)4]

Electrospray ionisation mass spectrometry (ESI-MS) has been used as an analytical tool in a wide-ranging scoping study of the alkylation and arylation reactions of [Pt₂(μ-S)₂(PPh₃)₄]. From these experiments, the factors that influence the formation of different product species - formed by mono- or di-alkylation - are determined. If the alkylating agent is an alkyl chloride or sulfate, monoalkylation followed by dialkylation of the two sulfido groups occurs, dependent on the alkylating power of the reagent used. For example, n-butyl chloride gives solely [Pt₂(μ-S)(μ-SBu)(PPh₃)₄]⁺ while dimethyl sulfate gives [Pt₂(μ-SMe)₂(PPh₃)₄]²⁺. This species, previously unisolated is stable in the absence of good nucleophiles, but the addition of potassium iodide results in rapid conversion to [Pt₂(μ-SMe)₂(PPh₃)₃I]⁺. This iodo complex is also observed from the reaction of [Pt₂(μ-S)₂(PPh₃)₄] with excess MeI, after the initial formation of mono- and di-methylated species. In these reactions, the iodide presumably displaces a phosphine ligand, which is then quaternised by excess alkylating agent. Changing the alkylating agent to a longer chain alkyl iodide or methyl bromide decreases the rate of alkylation of the sulfide in the initially formed [Pt₂(μ-S)(μ-SR)(PPh₃)₄]⁺. Mixed-thiolate species of the type [Pt₂(μ-SMe)(μ-SR)(PPh₃)₄]²⁺ are easily generated by reaction of [Pt₂(μ-S)(μ-SR)(PPh₃)₄]⁺ with excess Me₂SO₄ and is also dependent on the avoidance of nucleophiles. Reactions towards α,ω-dialkylating agents are surveyed; the chain length is found to have a dramatic effect on the rate of the second intramolecular cyclisation process, illustrated by a competitive reactivity study involving a mixture of Br(CH₂)₄Br and Br(CH₂)₅Br; on completion of the reaction the former gives [Pt₂{μ-S(CH₂)₄S}(PPh₃)₄]²⁺ while the latter predominantly gives monoalkylated[Pt₂(μ-S){μ-S(CH₂)₅Br}(PPh₃)₄]⁺. The reactivity of o- and p-dihaloxylenes has been explored, with the reaction with p-BrCH₂C₆H₄CH₂Br giving the bridged species [(PPh₃)₄Pt₂(μ-S)(μ-SCH₂C₆H₄CH₂S)(μ-S)Pt₂(PPh₃)₄]²⁺. Arylation reactions of [Pt₂(μ-S)₂(PPh₃)₄] with halobenzenes and 2-bromoheterocyclic compounds (pyridine, thiophene) are also described.     

Transition metal complexes with sulfur ligands. XXVIII. Ruthenium complexes of the pentadentate thioether thiolate ligands dpttd (2,3,11,12-dibenzo-1,4,7,10,13-pentathiatridecane(−2)) and the sterically demanding derivative bu4-dpttd (14,16,18,20-tetra (t-butyl)-2,3,11,12-dibenzo-1,4,7,10,13-pentathiatridecane(−2))

The template alkylation of Li₂[Ru(CO)₂(S₂C₆H₄)₂] (S₂C₆H₄²⁻ = 1,2-benzenedithiolate(−2)) by S(C₂H₄Br)₂ yields [Ru(CO)₂(dpttd)] (dpttd²⁻ = 3,11,12-dibenzo-1,4,7,10,13-pentathiatridecane(−2)) which is thermally converted into the monocarbonyl complex [Ru(CO)(dpttd)]. The reactions of dpttd-H₂ or dpttd²⁻ with [RuCl₂(PPh₃)₃], [RuCl₂(DMSO)₄], [RuCl₃(PhSCH₃)₃] and RuCl₃(NO)·xH₂O lead to [Ru(L)(dpttd)] and [Ru(L)(dpttd)]Cl (L = PPh₃, DMSO, PhSCH₃, NO), respectively, which are practically insoluble in all common solvents. Better soluble complexes are obtained with the new sterically demanding ligand ^tbu₄-dpttd²⁻ = 14,16,18,20-tetra(t-butyl)-2,3,11,12-dibenzo-1,4,7, 10,13-pentathiatridecane(−2); it is obtained in isomerically pure form by the reaction of tetrabuthylammonium-3,5-di (t-butyl)-1,2-benzenethiolthiolate, NBu₄[^tbu₂-C₆H₂S(SH), with S(C₂H₄Br)₂ and yields on reaction with [RuCl₂(PPh₃)₃] the very soluble [Ru(PPh₃)₂(^tbu₄-dpttd)] as well as [Ru(PPh₃(^tbu₄-dpttd)]. The ¹H NMR and ³¹P NMR spectra indicate that in solution [Ru(PPh₃)₂(^tbu₄-dpttd)] exists as a mixture of diastereomers, whereas [Ru(PPh₃)(^tbu₄-dpttd)] forms one pair of enantiomers only. This was confirmed by an X-ray structure determination of a single crystal. [Ru(PPh₃)(^tbu₄-dpttd)] crystallizes in space group P2₁/n with a = 10.496(4), b = 14.888(6), c = 32.382(12) Å, β = 98.04(3)°, Z = 4 and D_calc. = 1.27 g/cm³, R = 4.84; R_W = 5.06%; the ruthenium center is coordinated pseudooctahedrally by one phosphorus, two thiolate and three thiother S atoms.     

Synthesis, characterization and reactivity of polypyridyl ruthenium(II) carbonyl complexes with phosphine derivatives: Ruthenium-carbon bond labilization based on steric and electronic effects

Ruthenium phosphine complexes with a CO ligand [Ru(tpy)(PR₃)(CO)Cl]⁺ (tpy = 2,2′:6′,2″-terpyridine, R = Ph or p-tolyl), were prepared by introduction of CO gas to the corresponding dichloro complexes at room temperature. New carbonyl complexes were characterized by various methods including structural analyses. They were shown to release CO following the addition of several N-donors to form the corresponding substituted complexes. The kinetic data and structural results observed in this study indicated that the CO release reactions proceeded in an interchange mechanism. The molecular structures of [Ru(tpy)(PPh₃)(CO)Cl]PF₆, [Ru(tpy)(P(p-tolyl)₃)(CO)Cl]PF₆ and [Ru(tpy)(PPh₃)(CH₃CN)Cl]PF₆ were determined by X-ray crystallography.     

Ruthenium PCP–bis(phosphinite) pincer complexes

The reactions of [RuHCl(CO)(PPh₃)₃] with resorcinol bis(phosphinite) pincer ligands lead to complexes of the general formula [RuCl(PCP)(CO)(PPh₃)]; the crystal structure of one example has been determined. The structures of the bulky resorcinol 2-methyl-4,6-di-tert-butyl resorcinol and its mono-diisopropylphosphinite derivative were also determined. Reactions of [RuCl₂(PPh₃)₃] with resorcinol bis(phosphinite) ligands yield complexes of the type [RuCl(PCP)(PPh₃)], while the reaction of C₆H-2-Me-4,6-^tBu₂-1,3-(OPPh₂) with [RuHCl(CO)(PPh₃)₃] provides a PCP–pincer complex in which the ligand has undergone 2-methyl C–H activation.     

Cyclodiphosphazane appended with thioether functionality: Synthesis, transition metal chemistry and catalytic application in Suzuki-Miyaura cross-coupling reactions

The coordination chemistry of thioether functionalized cyclodiphosphazane ligand, cis-{^tBuNP(OCH₂CH₂SCH₃)}₂ (1) is described. The reactions of 1 with [Pd (COD)Cl₂] in 1:1, 1:2 and 2:1 M ratios afforded cis-[PdCl₂{^tBuNP(OCH₂CH₂SCH₃)}₂] (2), cis-[{PdCl₂}₂{^tBuNP(OCH₂CH₂SCH₃)}₂] (3) and trans-[PdCl₂{(^tBuNP(OCH₂CH₂SCH₃))₂}₂] (4), respectively. Treatment of 1 with [Pd(PEt₃)Cl₂]₂ or [PdCl(η³-C₃H₅)]₂ in appropriate molar ratios produce the mono- and binuclear complexes [PdCl₂(PEt₃{^tBuNP(OCH₂CH₂SCH₃)}₂] (5) and [{PdCl(η³-C₃H₅)}₂{^tBuNP(OCH₂CH₂SCH₃)}₂] (6) in good yield. The reaction of 1 with [{Ru(p-cymene)Cl₂}₂] afforded the mononuclear cationic complex, [{(p-cymene)RuCl{^tBuNP(OCH₂CH₂SCH₃)}₂]Cl (7), whereas the reactions of [Rh(COD)Cl]₂, [Pt(COD)Cl₂] and [Au(SMe₂)Cl] with 1 yielded the corresponding P-coordinated neutral complexes, [RhCl(COD){^tBuNP(OCH₂CH₂SCH₃)}₂] (8)cis-[PtCl₂{^tBuNP(OCH₂CH₂SCH₃)}₂] (9), respectively. The binuclear palladium(II) complex 3 was found to be an effective catalyst for the Suzuki-Miyaura cross-coupling reactions.