Synthesis, structures, and properties of group 9- and group 10-group 6 heterodinuclear nitrosyl complexes

The reaction of the group 9 bis(hydrosulfido) complexes [Cp*M(SH)2(PMe3)] (M=Rh, Ir; Cp*=eta(5)-C 5Me5) with the group 6 nitrosyl complexes [Cp*M'Cl2(NO)] (M'=Mo, W) in the presence of NEt3 affords a series of bis(sulfido)-bridged early-late heterobimetallic (ELHB) complexes [Cp*M(PMe3)(mu-S)2M'(NO)Cp*] (2a, M=Rh, M'=Mo; 2b, M=Rh, M'=W; 3a, M=Ir, M'=Mo; 3b, M=Ir, M'=W). Similar reactions of the group 10 bis(hydrosulfido) complexes [M(SH)2(dppe)] (M=Pd, Pt; dppe=Ph 2P(CH2) 2PPh2), [Pt(SH)2(dppp)] (dppp=Ph2P(CH2) 3PPh2), and [M(SH)2(dpmb)] (dpmb=o-C6H4(CH2PPh2)2) give the group 10-group 6 ELHB complexes [(dppe)M(mu-S)2M'(NO)Cp*] (M=Pd, Pt; M'=Mo, W), [(dppp)Pt(mu-S)2M'(NO)Cp*] (6a, M'=Mo; 6b, M'=W), and [(dpmb)M(mu-S)2M'(NO)Cp*] (M=Pd, Pt; M'=Mo, W), respectively. Cyclic voltammetric measurements reveal that these ELHB complexes undergo reversible one-electron oxidation at the group 6 metal center, which is consistent with isolation of the single-electron oxidation products [Cp*M(PMe3)(mu-S)2M'(NO)Cp*][PF6] (M=Rh, Ir; M'=Mo, W). Upon treatment of 2b and 3b with ROTf (R=Me, Et; OTf=OSO 2CF 3), the O atom of the terminal nitrosyl ligand is readily alkylated to form the alkoxyimido complexes such as [Cp*Rh(PMe3)(mu-S)2W(NOMe)Cp*][OTf]. In contrast, methylation of the Rh-, Ir-, and Pt-Mo complexes 2a, 3a, and 6a results in S-methylation, giving the methanethiolato complexes [Cp*M(PMe3)(mu-SMe)(mu-S)Mo(NO)Cp*][BPh 4] (M=Rh, Ir) and [(dppp)Pt(mu-SMe)(mu-S)Mo(NO)Cp*][OTf], respectively. The Pt-W complex 6b undergoes either S- or O-methylation to form a mixture of [(dppp)Pt(mu-SMe)(mu-S)W(NO)Cp*][OTf] and [(dppp)Pt(mu-S) 2W(NOMe)Cp*][OTf]. These observations indicate that O-alkylation and one-electron oxidation of the dinuclear nitrosyl complexes are facilitated by a common effect, i.e., donation of electrons from the group 9 or 10 metal center, where the group 9 metals behave as the more effective electron donor.     

Sulfur-bridged early-late heterobimetallics synthesized by incorporation of titanium,vanadium, and molybdenum into bis(hydrosulfido) templates of group 9 metals

Reactions of the bis(hydrosulfido) complexes [Cp*Rh(SH)(2)(PMe(3))] (1a; Cp* = eta(5)-C(5)Me(5)) with [CpTiCl(3)] (Cp = eta(5)-C(5)H(5)) and [TiCl(4)(thf)(2)] in the presence of triethylamine led to the formation of the sulfido-bridged titanium-rhodium complexes [Cp*Rh(PMe(3))(micro(2)-S)(2)TiClCp] (2a) and [Cp*Rh(PMe(3))(micro2-S)(2)TiCl(2)] (3a), respectively. Complex 3a and its iridium analogue 3b were further converted into the bis(acetylacetonato) complexes [Cp*M(PMe(3))(micro(2)-S)(2)Ti(acac)(2)] (4a, M = Rh; 4b, M = Ir) upon treatment with acetylacetone. The hydrosulfido complexes 1a and [Cp*Ir(SH)(2)(PMe(3))] (1b) also reacted with [VCl(3)(thf)(3)] and [Mo(CO)(4)(nbd)] (nbd = 2,5-norbornadiene) to afford the cationic sulfido-bridged VM2 complexes [(Cp*M(PMe(3))(micro2-S)(2))2V](+) (5a(+), M = Rh; 5b(+), M = Ir) and the hydrosulfido-bridged MoM complexes [Cp*M(PMe(3))(micro2-SH)(2)Mo(CO)(4)] (6a, M = Rh; 6b, M = Ir), respectively.     

Heterolytic cleavage of dihydrogen promoted by sulfido-bridged tungsten-ruthenium dinuclear complexes

A series of sulfido-bridged tungsten-ruthenium dinuclear complexes Cp*W(mu-S)(3)RuX(PPh(3))(2) (4a; X = Cl, 4b; X = H), Cp*W(O)(mu-S)(2)RuX(PPh(3))(2) (5a; X = Cl, 5b; X = H), and Cp*W(NPh)(mu-S)(2)RuX(PPh(3))(2) (6a; X = Cl, 6b; X = H) have been synthesized by the reactions of (PPh(4))[Cp*W(S)(3)] (1), (PPh(4))[Cp*W(O)(S)(2)] (2), and (PPh(4))[Cp*W(NPh)(S)(2)] (3), with RuClX(PPh(3))(3) (X = Cl, H). The heterolytic cleavage of H(2) was found to proceed at room temperature upon treating 5a and 6a with NaBAr(F)(4) (Ar(F) = 3, 5-C(6)H(3)(CF(3))(2)) under atmospheric pressure of H(2), which gave rise to [Cp*W(OH)(mu-S)(2)RuH(PPh(3))(2)](BAr(F)(4)) (7a) and [Cp*W(NHPh)(mu-S)(2)RuH(PPh(3))(2)](BAr(F)(4)) (8), respectively. When Cp*W(O)(mu-S)(2)Ru(PPh(3))(2)H (5b) was treated with a Br?nstead acid, [H(OEt(2))(2)](BAr(F)(4)) or HOTf, protonation occurred exclusively at the terminal oxide to give [Cp*W(OH)(mu-S)(2)RuH(PPh(3))(2)](X) (7a; X = BAr(F)(4), 7b; X = OTf), while the hydride remained intact. The analogous reaction of Cp+W(mu-S)(3)Ru(PPh(3))(2)H (4b) led to immediate evolution of H(2). Selective deprotonation of the hydroxyl group of 7a or 7b was induced by NEt(3) and 4b, generating Cp*W(O)(mu-S)(2)Ru(PPh(3))(2)H (5b). Evolution of H(2) was also observed for the reactions of 7a or 7b with CH(3)CN to give [Cp*W(O)(mu-S)(2)Ru(CH(3)CN)(PPh(3))(2)](X) (11a; X = BAr(F)(4), 11b; X = OTf). We examined the H/D exchange reactions of 4b, 5b, and 7a with D(2) and CH(3)OD, and found that facile H/D scrambling over the W-OH and Ru-H sites occurred for 7a. Based on these experimental results, the mechanism of the heterolytic H(2) activation and the reverse H(2) evolution reactions are discussed.     

Cubane-type heterometallic sulfido clusters: incorporation of two metal fragments into a dinuclear ReS(mu-S)2ReS core affording bimetallic M2Re2(mu 3-S)4 clusters (M = Ru,Pt, Cu) or trimetallic MM'Re2(mu 3-S)4 clusters via incomplete cubane-type MRe2(mu 3-S)(mu 2-S)3 intermediates (M = Ru,Rh, Ir; M' = Mo,W, Pd,Ru, Rh)

Reactions of a dirhenium tetra(sulfido) complex [PPh(4)](2)[ReS(L)(mu-S)(2)ReS(L)] (L = S(2)C(2)(SiMe(3))(2)) with a series of group 8-11 metal complexes in MeCN at room temperature afforded either the cubane-type clusters [M(2)(ReL)(2)(mu(3)-S)(4)] (M = CpRu (2), PtMe(3), Cu(PPh(3)) (4); Cp = eta(5)-C(5)Me(5)) or the incomplete cubane-type clusters [M(ReL)(2)(mu(3)-S)(mu(2)-S)(3)] (M = (eta(6)-C(6)HMe(5))Ru (5), CpRh (6), CpIr (7)), depending on the nature of the metal complexes added. It has also been disclosed that the latter incomplete cubane-type clusters can serve as the good precursors to the trimetallic cubane-type clusters still poorly precedented. Thus, treatment of 5-7 with a range of metal complexes in THF at room temperature resulted in the formation of novel trimetallic cubane-type clusters, including the neutral clusters [[(eta(6)-C(6)HMe(5))Ru][W(CO)(3)](ReL)(2)(mu(3)-S)(4)], [(CpM)[W(CO)(3)](ReL)(2)(mu(3)-S)(4)] (M = Rh, Ir), [(Cp*Ir)[Mo(CO)(3)](ReL)(2)(mu(3)-S)(4)], [[(eta(6)-C(6)HMe(5))Ru][Pd(PPh(3))](ReL)(2)(mu(3)-S)(4)], and [(Cp*Ir)[Pd(PPh(3))](ReL)(2)(mu(3)-S)(4)] (13) along with the cationic clusters [(Cp*Ir)(CpRu)(ReL)(2)(mu(3)-S)(4)][PF(6)] (14) and [(Cp*Ir)[Rh(cod)](ReL)(2)(mu(3)-S)(4)][PF(6)] (cod = 1,5-cyclooctadiene). The X-ray analyses have been carried out for 2, 4, 7, 13, and the SbF(6) analogue of 14 (14') to confirm their bimetallic cubane-type, bimetallic incomplete cubane-type, or trimetallic cubane-type structures. Fluxional behavior of the incomplete cubane-type and trimetallic cubane-type clusters in solutions has been demonstrated by the variable-temperature (1)H NMR studies, which is ascribable to both the metal-metal bond migration in the cluster cores and the pseudorotation of the dithiolene ligand bonded to the square pyramidal Re centers, where the temperatures at which these processes proceed have been found to depend upon the nature of the metal centers included in the cluster cores.     

Mixed phosphine and group-13 metal ligator complexes [(PR3)(a)M(ECp*)b] (M = Mo, Ni; E = Ga, Al; R = C6H5, cyclo-C6H11, CH3)

Treatment of [Mo(N(2))(PMe(3))(5)] with two equivalents GaCp* (Cp* = η(5)-C(5)(CH(3))(5)) leads to the formation of cis-[Mo(GaCp*)(2)(PMe(3))(4)] (1), while AlCp* did not react with this precursor. In addition, [Ni(GaCp*)(2)(PPh(3))(2)] (2a), [Ni(AlCp*)(2)(PPh(3))(2)] (2b), [Ni(GaCp*)(2)(PCy(3))(2)] (3a), [Ni(GaCp*)(2)(PMe(3))(2)] (3b), [Ni(GaCp*)(3)(PCy(3))] (4) and [Ni(GaCp*)(PMe(3))(3)] (5) have been prepared in high yields by a direct synthesis from [Ni(COD)(2)] and stoichiometric amounts of the ligands PR(3) and ECp* (E = Al, Ga), respectively. All compounds have been fully characterized by (1)H, (13)C, and (31)P NMR spectroscopy, elemental analysis and single crystal X-ray diffraction studies.     

Synthesis and reactivity of the monomeric late-transition-metal parent amido complex [Ir(Cp*)(PMe3)(Ph)(NH2)

The late-transition-metal parent amido compound [Ir(Cp*)(PMe3)(Ph)(NH2)] (2) has been synthesized by deprotonation of the corresponding ammine complex [Ir(Cp*)(PMe3)(Ph)(NH3)][OTf] (6) with KN(SiMe3)2. An X-ray structure determination has ascertained its monomeric nature. Proton-transfer studies indicate that 2 can successfully deprotonate p-nitrophenylacetonitrile, aniline, and phenol. Crystallographic analysis has revealed that the ion pair [Ir(Cp*)(PMe3)(Ph)(NH3)][OPh] (8) exists as a hydrogen-bonded dimer in the solid state. Reactions of 2 with isocyanates and carbodiimides lead to overall insertion of the heterocumulenes into the N--H bond of the Ir-bonded amido group, demonstrating the ability of 2 to act as an efficient nucleophile. Intriguing reactivity is observed when amide 2 reacts with CO or 2,6-dimethylphenyl isocyanide. eta4-Tetramethylfulvene complexes [Ir(eta4-C5Me4CH2)(PMe3)(Ph)(L)] (L=CO (15), CNC6H3-2,6-(CH3)2 (16)) are formed in solution through displacement of the amido group by the incoming ligand followed by deprotonation of a methyl group on the Cp* ring and liberation of ammonia. Conclusive evidence for the presence of the Ir-bonded eta4-tetramethylfulvene moiety in the solid state has been provided by an X-ray diffraction study of complex 16.     

Quasi-octahedral complexes of pentamethylcyclopentadienyliridium(III) bearing bis(diphenylphosphinomethyl)phenylphosphine (dpmp)

Reaction of [Cp*IrCl2]2 (1) with dpmp in the presence of KPF6 afforded a binuclear complex [Cp*IrCl(dpmp-P1,P2;P3)IrCl2Cp*](PF6) (2) (dpmp =(Ph2PCH2)2PPh). The mononuclear complex [Cp*IrCl(dpmp-P1,P2)](PF6) (4) was generated by the reaction of [Cp*IrCl2(BDMPP)](BDMPP =PPh[2,6-(MeO)2C6H3]2) with dpmp in the presence of KPF6. These mono- and binuclear complexes have four-membered ring structures with a terminal and a central P atom of the dpmp ligand coordinated to an iridium atom as a bidentate ligand. Since there are two chiral centers at the Ir atom and a central P2 atom, there are two diastereomers that were characterized by spectrometry. Complexes anti-4 and syn-4 reacted with [Cp*RhCl2]2 or [(C6Me6)RuCl2]2, giving the corresponding mixed-metal complexes, anti- and syn- [Cp*IrCl(dppm-P1,P2;P3)MCl2L](PF6) (6: M = Rh, L = Cp*; 7: M = Ru, L = C6Me6). Treatment with AuCl(SC4H8) gave tetranuclear complexes, anti- and syn-8 [[Cp*IrCl(dppm-P1,P2;P3)AuCl]2](PF6)2 bearing an Au-Au bond. Reaction of anti- with PtCl2(cod) generated the trinuclear complex anti-9, anti-[[Cp*IrCl(dppm-P1,P2;P3)]2PtCl2](PF6)2. These reactions proceeded stereospecifically. The P,O-chelated complex syn-[Cp*IrCl(BDMPP-P,O)] (syn-10)(BDMPP-P,O = PPh[2,6-(MeO)2C6H3][2-O-6-(MeO)C6H3]2) reacted with dpmp in the presence of KPF6, generating the corresponding anti-complex as a main product as well as a small amount of syn-complex, [Cp*Ir(BDMPP-P,O)(dppm-P1)](PF6) (11). The reaction proceeded preferentially with inversion. The reaction processes were investigated by PM3 calculation. anti- was treated with MCl2(cod), giving anti-[Cp*Ir(BDMPP-P,O)(dppm-P1;P2,P3)MCl2](PF6)(14: M = Pt; 15: M = Pd), in which the MCl2 moiety coordinated to the two free P atoms of anti-11. The X-ray analyses of syn-2, anti-2, anti-4, anti-8 and anti-11 were performed.     

Inter- and intramolecular activation of aromatic C-H bonds by diphosphine and hydrido-bridged dinuclear iridium complexes

Reactions of [(Cp*Ir)2(mu-dmpm)(mu-H)2]2+ (1) with NaOtBu in aromatic solvent at room temperature give [(Cp*Ir)(H)(mu-dmpm)(mu-H)(Cp*Ir)(Ar)]+ [Ar = Ph (3), p-Tol (4a), m-Tol (4b), 2-furanyl (5a), 3-furanyl (5b)] via intermolecular aromatic C-H activation. Treatment of [(Cp*Ir)2(mu-dppm)(mu-H)2]2+ (2) with base (Et2NH) results in intramolecular C-H activation of the phenyl group in the dppm ligand to give [(Cp*Ir)(H){mu-PPh(C6H4)CH2PPh2}(mu-H)(Cp*Ir)]+ (6). The structures of 3, 5a, and 6 have been determined by X-ray diffraction methods.     

Activation and coordination of ammonia at [cp*ir(h)(2) ]: NMR and matrix isolation studies

(1) H?NMR exchange spectroscopy of a reaction mixture of [Cp*Ir(H)(4) ] (1; Cp*=1,2,3,4,5-pentamethylcyclopentadienyl) and ammonia suggests an exchange of hydrogen atoms between the hydrido ligands and ammonia. Treatment of 1 with ND(3) led to an H/D exchange between ND(3) and the hydrido ligands of 1. Subsequent studies showed that photolysis of 1 isolated in frozen argon matrices leads to the formation of the iridium compounds [Cp*Ir(H)(2) ] (2) and [Cp*Ir(H)(3) ] (4), as it was confirmed by IR spectroscopy. In the presence of water the aqua complex [Cp*Ir(H)(2) (OH(2) )] (3) was generated simultaneously. Accordingly, photolysis of 1 in an argon matrix doped with ammonia gave rise to the ammine complex [Cp*Ir(H)(2) (NH(3) )] (5). IR assignments were supported by calculations of the gas-phase IR spectra of 1-5 by DFT methods.     

Silylenediamido [(CH3)2Si(NTs)2(2-); Ts = p-CH3C6H4SO2] complexes of iridium: synthesis, structures and facile Si-N bond cleavage

The N,N'-bis(sulfonyl)diaminosilane TsdmsinH(2) (TsdmsinH(2) = (CH(3))(2)Si(NHTs)(2), Ts = p-CH(3)C(6)H(4)SO(2)) reacted with [Cp*IrCl(2)](2) (Cp* = eta(5)-C(5)(CH(3))(5)) in the presence of a base to give the coordinatively unsaturated (silylenediamido)iridium complex [Cp*Ir(Tsdmsin)] (2), which was further converted to the 18e adducts [Cp*Ir(Tsdmsin)L] (L = P(C(6)H(5))(3) (3a), P(OC(2)H(5))(3), CO); the reactions of 2 and 3a with water led to the formation of the imido-bridged dinuclear complex [Cp*Ir(micro(2)-NTs)(2)IrCp*] and the bis(amido) complex [Cp*Ir(NHTs)(2){P(C(6)H(5))(3)}], respectively.     

The elusive 16-electron Cp*M(NO)Me(2)(M = Mo, W) complexes and their spontaneous conversions to Cp*M(NMe)(O)Me isomers.

Treatment of [Cp*Mo(NO)Cl(mu-Cl)](2) with magnesium (Me(2)Mg.dioxane, MeMgCl) or aluminum (Me(3)Al) methylating reagents affords the known compound [Cp*Mo(NO)Me(mu-Cl)](2) (1). Similar treatment of the dichloro precursor with MeLi in ethereal solvents generates an equimolar mixture of 1 and the trimethyl "ate" complex, Cp*MoMe(3)(NO-Li(OEt(2)(n)), (2-Et(2)O). Reaction of 2-Et(2)O with a source of [Me](+) forms Cp*MoMe(3)(=N-OMe)(3), a rare terminal alkoxylimido complex. Metathesis of the chloro ligands of [Cp*Mo(NO)Cl(mu-Cl)](2) by MeLi in toluene at low temperatures produces the target dimethyl complex, Cp*Mo(NO)Me(2) (4), in 75% isolated yield. In solution, 4 is predominantly a monomeric species, whereas in the solid state it adopts a dimeric or oligomeric structure containing isonitrosyl bridges as indicated by IR and (15)N/(13)C NMR spectroscopies. Hydrolysis of 4 affords meso- and rac-[Cp*Mo(NO)Me](2)(mu-O) (5), and the reactions of 4 with a range of Lewis bases, L, to form the 18e adducts Cp*Mo(NO)(L)Me(2) (e.g., Cp*Mo(NO)(PMe(3))Me(2) (7)), have established it to be the most electrophilic complex of its family. Acidolysis of the methyl groups of 4 is also facile. Most notably, 4 is thermally unstable in solution and undergoes isomerization via nitrosyl N-O bond cleavage to its oxo(imido) form, Cp*Mo(NMe)(O)Me (11), which is isolable from the final reaction mixture as the mu-oxo-bridged adduct formed by 4 and 11, i.e., Cp*Mo(NO)Me(2)(mu-O)Cp*Mo(NMe)Me (4 <-- 11). The rate of this isomerization is significantly faster for the tungsten dimethyl complex; hence, Cp*W(NO)Me(2) (12) is not isolable free of a supporting donor interaction and can only be isolated as Cp*W(NO)Me(2)(mu-O)Cp*W(NMe)Me (12 <-- 13) or Cp*W(NO)Me(2)(PMe(3)) (14) adducts.     

Synthesis and characterization of heterometallic clusters (Ir2Rh, Ir2W, Rh3) Containing 1,2-dicarba-closo-dodecaborane(12)-1,2-dithiolate chelate ligands, [(B10H10)C2S2]2-

The 16-electron half-sandwich complex [Cp*Ir[S2C2(B10H10)]] (Cp* = eta5-C5Me5) (1a) reacts with [[Rh(cod)(mu-Cl)]2] (cod = cycloocta-1,5-diene, C8H12) in different molar ratios to give three products, [[Cp*Ir[S2C2(B10H9)]]Rh(cod)] (2), trans-[[Cp*Ir[S2C2(B10H9)]]Rh[[S2C2(B10H10)]IrCp*]] (3), and [Rh2(cod)2[(mu-SH)(mu-SC)(CH)(B10H10)]] (4). Complex 3 contains an Ir2Rh backbone with two different Ir-Rh bonds (3.003(3) and 2.685(3) angstroms). The dinuclear complex 2 reacts with the mononuclear 16-electron complex 1a to give 3 in refluxing toluene. Reaction of 1a with [W(CO)3(py)3] (py = C5H5N) in the presence of BF3.EtO2 leads to the trinuclear cluster [[Cp*Ir[S2C2(B10H10)]]2W(CO)2] (5) together with [[Cp*Ir(CO)[S2C2(B10H10)]]W(CO)5] (6), and [Cp*Ir(CO)[S2C2(B10H10)]] (7). Analogous reactions of [Cp*Rh[S2C2(B10H10)]] (1 b) with [[Rh(cod)(mu-Cl)]2] were investigated and two complexes cis-[[Cp*Rh[S2C2(B10H10)]]2Rh] (8) and trans-[[Cp*Rh[S2C2(B10H10)]]2Rh] (9) were obtained. In refluxing THF solution, the cisoid 8 is converted in more than 95 % yield to the transoid 9. All new complexes 2-9 were characterized by NMR spectroscopy (1H, 11B NMR) and X-ray diffraction structural analyses are reported for complexes 2-5, 8, and 9.     

Construction of trinuclear iridium clusters through ancillary ortho-carborane-1,2-diselenolato ligands, with simultaneous iridium-induced B-H activation

The reaction of the 16-electron "pseudo-aromatic" complex Cp*Ir[Se2C2(B10H10)] (1, Cp* = eta5-C5Me5) with [Ir(cod)(micro-OC2H5)]2 leads to the trinuclear iridium complexes {(cod)Ir[Se2C2(B10H8)(OC2H5)]}Ir{[Se2C2(B10H10)]IrCp*} (2), {(cod)Ir[Se2C2(B10H8)(OC2H5)]}Ir{[Se2C2(B10H9)]IrCp*} (3), {Cp*Ir[Se2C2(B10H9)]}{IrSe(2)[C2(B10H9)(OC2H5)]}{[Se2C2(B10H10)] IrCp*} (4) and one mononuclear complex Cp*Ir[Se2C2(B10H8)(OC2H5)(2)] (5). The reactivity of 2 was investigated and revealed that transformation from 2 to 3 occurred thermally in solution. The transoid complex 2 (with the carborane diselenolato units in trans position) can be converted in nearly 90% yield to the cisoid complex 3. In complexes 2, 3, two diselenolato carborane ligands bridge the Ir(3) core, which consists of Ir-Ir metal bonds. Compared with transoid 2, the cisoid 3 contains two iridium-boron bonds. Complex 4 consists of three different coordination environment carborane ligands (Ir-B(cluster): {Cp*Ir[Se2C2(B10H9)]}, O-B(cluster): {[Se2C2(B10H9)](OC2H5)}, and intact carborane: {Cp*Ir[Se2C2 (B10H10)]}) without the presence of a metal-metal bond. Analogous reaction of 1 with [Ir(cod)(micro-OCH(3))](2) results in formation of the trinuclear complex {Cp*Ir[Se2C2(B10H9)]}{IrSe(2)[C2(B10H9)(OCH3)]}{[Se2C2(B10H10)]IrCp*} (6) and mononuclear complex Cp*Ir[Se2C2(B10H8)(OCH3)(2)] (7). The structures of 2, 3, 4, 5, 6 and 7 have been determined by crystallographic studies.     

Synthesis of Ru-Pt and Ru-Pd mixed-metal imido clusters from a diruthenium imido-methylene scaffold [(Cp*Ru)2(mu2-NPh)(mu2-CH2)

The diruthenium mu2-imido mu2-methylene complex [(Cp*Ru)2(mu2-NPh)(mu2-CH2)] serves as a bifunctional scaffold for cluster synthesis, producing a mu3-imido Ru2Pt cluster [(Cp*Ru)2(mu3-NPh)(mu2-CH2)Pt(PMe3)2] on treatment with [Pt(eta2-C2H4)(PMe3)2] and a mu3-methylidyne Ru4Pd2 cluster [(Cp*Ru)2(mu2-NPh)(mu3-CH)PdCl]2 with [PdMeCl(cod)].     

Synthesis and reactivity of Ir(I) and Ir(III) complexes with MeNH2, Me2C=NR (R = H, Me), C,N-C6H4{C(Me)=N(Me)}-2, and N,N'-RN=C(Me)CH2C(Me2)NHR (R = H, Me) ligands

Complexes [Ir(Cp*)Cl(n)(NH2Me)(3-n)]X(m) (n = 2, m = 0 (1), n = 1, m = 1, X = Cl (2a), n = 0, m = 2, X = OTf (3)) are obtained by reacting [Ir(Cp*)Cl(mu-Cl)]2 with MeNH2 (1:2 or 1:8) or with [Ag(NH2Me)2]OTf (1:4), respectively. Complex 2b (n = 1, m = 1, X = ClO 4) is obtained from 2a and NaClO4 x H2O. The reaction of 3 with MeC(O)Ph at 80 degrees C gives [Ir(Cp*){C,N-C6H4{C(Me)=N(Me)}-2}(NH2Me)]OTf (4), which in turn reacts with RNC to give [Ir(Cp*){C,N-C6H4{C(Me)=N(Me)}-2}(CNR)]OTf (R = (t)Bu (5), Xy (6)). [Ir(mu-Cl)(COD)]2 reacts with [Ag{N(R)=CMe2}2]X (1:2) to give [Ir{N(R)=CMe2}2(COD)]X (R = H, X = ClO4 (7); R = Me, X = OTf (8)). Complexes [Ir(CO)2(NH=CMe2)2]ClO4 (9) and [IrCl{N(R)=CMe2}(COD)] (R = H (10), Me (11)) are obtained from the appropriate [Ir{N(R)=CMe2}2(COD)]X and CO or Me4NCl, respectively. [Ir(Cp*)Cl(mu-Cl)]2 reacts with [Au(NH=CMe2)(PPh3)]ClO4 (1:2) to give [Ir(Cp*)(mu-Cl)(NH=CMe2)]2(ClO4)2 (12) which in turn reacts with PPh 3 or Me4NCl (1:2) to give [Ir(Cp*)Cl(NH=CMe2)(PPh3)]ClO4 (13) or [Ir(Cp*)Cl2(NH=CMe2)] (14), respectively. Complex 14 hydrolyzes in a CH2Cl2/Et2O solution to give [Ir(Cp*)Cl2(NH3)] (15). The reaction of [Ir(Cp*)Cl(mu-Cl)]2 with [Ag(NH=CMe2)2]ClO4 (1:4) gives [Ir(Cp*)(NH=CMe2)3](ClO4)2 (16a), which reacts with PPNCl (PPN = Ph3=P=N=PPh3) under different reaction conditions to give [Ir(Cp*)(NH=CMe2)3]XY (X = Cl, Y = ClO4 (16b); X = Y = Cl (16c)). Equimolar amounts of 14 and 16a react to give [Ir(Cp*)Cl(NH=CMe2)2]ClO4 (17), which in turn reacts with PPNCl to give [Ir(Cp*)Cl(H-imam)]Cl (R-imam = N,N'-N(R)=C(Me)CH2C(Me)2NHR (18a)]. Complexes [Ir(Cp*)Cl(R-imam)]ClO4 (R = H (18b), Me (19)) are obtained from 18a and AgClO4 or by refluxing 2b in acetone for 7 h, respectively. They react with AgClO4 and the appropriate neutral ligand or with [Ag(NH=CMe2)2]ClO4 to give [Ir(Cp*)(R-imam)L](ClO4)2 (R = H, L = (t)BuNC (20), XyNC (21); R = Me, L = MeCN (22)) or [Ir(Cp*)(H-imam)(NH=CMe2)](ClO4)2 (23a), respectively. The later reacts with PPNCl to give [Ir(Cp*)(H-imam)(NH=CMe2)]Cl(ClO4) (23b). The reaction of 22 with XyNC gives [Ir(Cp*)(Me-imam)(CNXy)](ClO4)2 (24). The structures of complexes 15, 16c and 18b have been solved by X-ray diffraction methods.     

Half-sandwich cyclopentandienyl molybdenum and tungsten nitrosyl complexes containing bidentate sulfur ligands

Half-sandwich nitrosyl complexes Cp*M(NO)I2 (M = Mo, or W) react with dithiocarbamates (NaS2CNMe2 and NaS2CNEt2) in THF to form of complexes: Cp*Mo(NO)I (S2CNMe2) (1), Cp*Mo(NO)I(S2CNEt2) (2), Cp*W(NO)I(S2CNMe2) (3) and Cp*W(NO)I(S2CNEt2) (4) in high yields. Treatments of Cp*M(NO)I2 (M = Mo, W) or [CpMo(NO)I2]2 with phosphinodithioate (NaS2PMe2) and phosphorodithioate [(NH4)S2P(OMe)2] result in complexes: Cp*Mo(NO)I(S2PMe2) (5a), CpMo(NO)I (S2PMe2) (5b), Cp*Mo(NO)(S2PMe2)2 (6a), CpMo (NO) (S2PMe2)2 (6b) and Cp*Mo(NO)I[S2P(OMe)2] (7), Cp*W(NO)I(S2PMe2) (8), Cp*W(NO) I[S2P(OMe)]2 (9). Treatment of (5a) and (5b) with an excess of NaS2PMe2 gives (6a) and (6b). The complexes have been characterized by their elemental analyses, i.r., 1H, 13C-n.m.r. and by EI-MS spectrometry.     

Iridium(III) complexes formed by O-H and/Or C-H activation of 2-(arylazo)phenols

Reaction of 2-(arylazo)phenols with [Ir(PPh(3))(3)Cl] in refluxing ethanol in the presence of a base (NEt(3)) affords complexes of three different types, viz. [Ir(PPh(3))(2)(NO-R)(H)Cl] (R = OCH(3), CH(3), H, Cl and NO(2)), [Ir(PPh(3))(2)(NO-R)(H)(2)] and [Ir(PPh(3))(2)(CNO-R)(H)]. Structures of the [Ir(PPh(3))(2)(NO-Cl)(H)Cl], [Ir(PPh(3))(2)(NO-Cl)(H)(2)] and [Ir(PPh(3))(2)(CNO-Cl)(H)] complexes have been determined by X-ray crystallography. In the [Ir(PPh(3))(2)(NO-R)(H)Cl] and [Ir(PPh(3))(2)(NO-R)(H)(2)] complexes, the 2-(arylazo)phenolate ligands are coordinated to the metal center as monoanionic bidentate N,O-donors, whereas in the [Ir(PPh(3))(2)(CNO-R)(H)] complexes, they are coordinated to iridium as dianionic tridentate C,N,O-donors. In all three products formed in ethanol, the two PPh(3) ligands are trans. Reaction of 2-(arylazo)phenols with [Ir(PPh(3))(3)Cl] in refluxing toluene in the presence of NEt(3) affords complexes of two types, viz. [Ir(PPh(3))(2)(CNO-R)(H)] and [Ir(PPh(3))(2)(CNO-R)Cl]. Structure of the [Ir(PPh(3))(2)(CNO-Cl)Cl] complex has been determined by X-ray crystallography, and the 2-(arylazo)phenolate ligand is coordinated to the metal center as a dianionic tridentate C,N,O-donor and the two PPh(3) ligands are cis. All of the iridium(III) complexes show intense MLCT transitions in the visible region. Cyclic voltammetry shows an Ir(III)-Ir(IV) oxidation on the positive side of SCE and an Ir(III)-Ir(II) reduction on the negative side for all of the products.     

Syntheses, structures, and reactivities of mono- and dinuclear iridium thiolato complexes containing nitrosyl ligands

Reactions of the iridium(III) nitrosyl complex [Ir(NO)Cl2(PPh3)2] (1) with hydrosulfide and arenethiolate anions afforded the square-pyramidal iridium(III) complex [Ir(NO)(SH)2(PPh3)2] (2) with a bent nitrosyl ligand and a series of the square-planar iridium(I) complexes [Ir(NO)(SAr)2(PPh3)] (3a, Ar = C6H2Me3-2,4,6 (Mes); 3b, Ar = C6H3Me2-2,6 (Xy); 3c, Ar = C6H2Pri3-2,4,6) containing a linear nitrosyl ligand, respectively. Complex 1 also reacted with alkanethiolate anions or alkanethiols to give the thiolato-bridged diiridium complexes [Ir(NO)(mu-SPri)(SPri)(PPh3)]2 (4) and [Ir(NO)(mu-SBut)(PPh3)]2 (5). Complex 4 contains two square-pyramidal iridium(III) centers with a bent nitrosyl ligand, whereas 5 contains two tetrahedral iridium(0) centers with a linear nitrosyl ligand and has an Ir-Ir bond. Upon treatment with benzoyl chloride, 3a and 3b were converted into the (diaryl disulfide)- and thiolato-bridged dichlorodiiridium(III) complexes [[IrCl(mu-SC6HnMe4-nCH2)(PPh3)]2(mu-ArSSAr)] (6a, Ar = Mes, n = 2; 6b, Ar = Xy, n = 3) accompanied by a loss of the nitrosyl ligands and cleavage of a C-H bond in an ortho methyl group of the thiolato ligands. Similar treatment of 4 gave the dichlorodiiridium complex [Ir(NO)(PPh3)(mu-SPri)3IrCl2(PPh3)] (7), which has an octahedral dichloroiridium(III) center and a distorted trigonal-bipyramidal Ir(I) atom with a linear nitrosyl ligand. The detailed structures of 3a, 4, 5, 6a, and 7 have been determined by X-ray crystallography.     

Coordination features of a hybrid scorpionate/phosphane ligand exemplified with Iridium

Although the pentacoordinated complex [Ir{(allyl)B(CH(2)PPh(2))(pz)(2)}(cod)] (1; pz=pyrazolyl, cod=1,5-cyclooctadiene), isolated from the reaction of [{Ir(mu-Cl)(cod)}(2)] with [Li(tmen)][B(allyl)(CH(2)PPh(2))- (pz)(2)] (tmen=N,N,N',N'-tetramethylethane-1,2-diamine), shows behavior similar to that of the related hydridotris(pyrazolyl)borate complex, the carbonyl derivatives behave in a quite different way. On carbonylation of 1, the metal--metal-bonded complex [(Ir{(allyl)B(CH(2)PPh(2))(pz)(2)}CO)(2)(mu-CO)] (2) that results has a single ketonic carbonyl bridge. This bridging carbonyl is labile such that upon treatment of 2 with PMe(3) the pentacoordinated Ir(I) complex [Ir(CO){(pz)B(eta(2)-CH(2)CH=CH(2))(CH(2)PPh(2))(pz)}(PMe(3))] (3) was isolated. Complex 3 shows a unique fac coordination of the hybrid ligand with the allyl group eta(2)-bonded to the metal in the equatorial plane of a distorted trigonal bipyramid with one pyrazolate group remaining uncoordinated. This unusual feature can be rationalized on the basis of the electron-rich nature of the metal center. The related complex [Ir(CO){(pz)B(eta(2)-CH(2)CH=CH(2))(CH(2)PPh(2))(pz)}(PPh(3))] (4) was found to exist in solution as a temperature-dependent equilibrium between the cis-pentacoordinated and trans square planar isomers with respect to the phosphorus donor atoms. Protonation of 3 with different acids is selective at the iridium center and gives the cationic hydrides [Ir{(allyl)B(CH(2)PPh(2))(pz)(2)}(CO)H(PMe(3))]X (X=BF(4) (5), MeCO(2) (6), and Cl (7)). Complex 7 further reacts with HCl to generate the unexpected product [Ir(CO)Cl{(Hpz)B(CH(2)PPh(2))(pz)CH(2)CH(Me)}(PMe(3))]Cl (9; Hpz=protonated pyrazolyl group) formed by the insertion of the hydride into the Ir-(eta(2)-allyl) bond. In contrast, protonation of complex 4 with HCl stops at the hydrido complex [Ir{(allyl)B(CH(2)PPh(2))(pz)(2)}(CO)H(PPh(3))]Cl (8). X-ray diffraction studies carried out on complexes 2, 3, and 9 show the versatility of the hybrid scorpionate ligand in its coordination.     

A mechanistic investigation of oxidative addition of methyl iodide to [Tp*Rh(CO)(L)

Reaction of methyl iodide with square planar [kappa(2)-Tp*Rh(CO)(PMe(3))] 1a (Tp* = HB(3,5-Me(2)pz)(3)) at room temperature affords [kappa(3)-Tp*Rh(CO)(PMe(3))(Me)]I 2a, which was fully characterized by spectroscopy and X-ray crystallography. The pseudooctahedral geometry of cationic 2a, which contains a kappa(3)-coordinated Tp* ligand, indicates a reaction mechanism in which nucleophilic attack by Rh on MeI is accompanied by coordination of the pendant pyrazolyl group. In solution 2a transforms slowly into a neutral (acetyl)(iodo) rhodium complex [kappa(3)-Tp*Rh(PMe(3))(COMe)I] 3a, for which an X-ray crystal structure is also reported. Kinetic studies on the reactions of [kappa(2)-Tp*Rh(CO)(L)] (L = PMe(3), PMe(2)Ph, PMePh(2), PPh(3), CO)] with MeI show second-order behavior with large negative activation entropies, consistent with an S(N)2 mechanism. The second-order rate constants correlate well with phosphine basicity. For L = CO, reaction with MeI gives an acetyl complex, [kappa(3)-Tp*Rh(CO)(COMe)I]. The bis(pyrazolyl)borate complexes [kappa(2)-Bp*Rh(CO)(L)] (L = PPh(3), CO) are much less reactive toward MeI than the Tp* analogues, indicating the importance of the third pyrazolyl group and the accessibility of a kappa(3) coordination mode. The results strengthen the evidence in favor of an S(N)2 mechanism for oxidative addition of MeI to square planar d(8) transition metal complexes.