Reactions of manganese and rhenium complexes with organic azides: preparation of tetraazabutadiene derivatives

Azide complexes [M(RN(3))(CO)(3)P(2)]BPh(4)[M = Mn, Re; R = C(6)H(5)CH(2), 4-CH(3)C(6)H(4)CH(2), C(6)H(5), 4-CH(3)C(6)H(4), C(5)H(9); P = PPh(OEt)(2), PPh(2)(OEt)] were prepared by allowing tricarbonyl MH(CO)(3)P(2) hydride complexes to react first with Br?nsted acid (HBF(4), CF(3)SO(3)H) and then with organic azide in the dark. In sunlight the reaction yielded tetraazabutadiene [M(eta(2)-1,4-R(2)N(4))(CO)(2)P(2)]BPh(4) complexes or, with benzyl azide, imine [M{eta(1)-NH[double bond, length as m-dash]C(H)Ar}(CO)(3)P(2)]BPh(4)(Ar = C(6)H(5), 4-CH(3)C(6)H(4)) derivatives. Tetraazabutadiene [M(eta(2)-1,4-R(2)N(4))(CO)(2)P(2)]BPh(4) complexes were also prepared by reacting dicarbonyl MH(CO)(2)P(3) species first with Br?nsted acid and then with an excess of organic azide. Complexes were characterised spectroscopically (IR, (1)H, (31)P, (13)C, (15)N NMR data) and by the X-ray crystal structure determination of complex [Re{eta(2)-1,4-(C(6)H(5)CH(2))(2)N(4)}(CO)(2){PPh(OEt)(2)}(2)]BPh(4)(). Strong evidence for coordination of the organic azide was obtained from the (15)N NMR spectra of labelled [M(C(6)H(5)CH(2)(15)NN(15)N)(CO)(3)P(2)]BPh(4) derivatives.     

Ruthenium tris(pyrazolyl)borate diazo complexes: preparation of aryldiazenido, aryldiazene, and hydrazine derivatives

Tris(pyrazolyl)borate aryldiazenido complexes [RuTpLL'(ArN(2))](BF(4))(2) (1-3) [Ar = C(6)H(5), 4-CH(3)C(6)H(4); Tp = hydridotris(pyrazolyl)borate; L = P(OEt)(3) or PPh(OEt)(2), L' = PPh(3); L = L' = P(OEt)(3)] were prepared by allowing dihydrogen [RuTp(eta(2)-H(2))LL'](+) derivatives to react with aryldiazonium cations. Spectroscopic characterization (IR, (15)N NMR) using the (15)N-labeled derivatives strongly supports the presence of a linear [Ru]-NN-Ar aryldiazenido group. Hydrazine complexes [RuTp(RNHNH(2))LL']BPh(4) (4-6) [R = H, CH(3), C(6)H(5), 4-NO(2)C(6)H(4); L = P(OEt)(3) or PPh(OEt)(2), L' = PPh(3); L = L' = P(OEt)(3)] were also prepared by reacting the [RuTp(eta(2)-H(2))LL'](+) cation with an excess of hydrazine. The complexes were characterized spectroscopically (IR and NMR) and by X-ray crystal structure determination of the [RuTp(CH(3)NHNH(2))[P(OEt)(3)](PPh(3))]BPh(4) (4d) derivative. Tris(pyrazolyl)borate aryldiazene complexes [RuTp(ArN=NH)LL']BPh(4) (7-9) (Ar = C(6)H(5), 4-CH(3)C(6)H(4)) were prepared following three different methods: (i). by allowing hydride species RuHTpLL' to react with aryldiazonium cations in CH(2)Cl(2); (ii). by treating aryldiazenido [RuTpLL'(ArN(2))](BF(4))(2) with LiBHEt(3) in CH(2)Cl(2); (iii). by oxidizing arylhydrazine [RuTp(ArNHNH(2))LL']BPh(4) complexes with Pb(OAc)(4) in CH(2)Cl(2) at -30 degrees C. Methyldiazene complexes [RuTp(CH(3)N=NH)LL']BPh(4) were also prepared by the oxidation of the corresponding methylhydrazine [RuTp(CH(3)NHNH(2))LL']BPh(4) with Pb(OAc)(4).     

Preparation and reactivity of mixed-ligand ruthenium(II) hydride complexes with phosphites and polypyridyls

Chloro complexes [RuCl(N-N)P3]BPh4 (1-3) [N-N = 2,2'-bipyridine, bpy; 1,10-phenanthroline, phen; 5,5'-dimethyl-2,2'-bipyridine, 5,5'-Me2bpy; P = P(OEt)3, PPh(OEt)2 and PPh2OEt] were prepared by allowing the [RuCl4(N-N)].H2O compounds to react with an excess of phosphite in ethanol. The bis(bipyridine) [RuCl(bpy)2[P(OEt)3]]BPh4 (7) complex was also prepared by reacting RuCl2(bpy)2.2H2O with phosphite and ethanol. Treatment of the chloro complexes 1-3 and 7 with NaBH4 yielded the hydride [RuH(N-N)P3]BPh4 (4-6) and [RuH(bpy)2P]BPh4 (8) derivatives, which were characterized spectroscopically and by the X-ray crystal structure determination of [RuH(bpy)[P(OEt)3]3]BPh4 (4a). Protonation reaction of the new hydrides with Br?nsted acid was studied and led to dicationic [Ru(eta2-H2)(N-N)P3]2+ (9, 10) and [Ru(eta(2-H2)(bpy)2P]2+ (11) dihydrogen derivatives. The presence of the eta2-H2 ligand was indicated by a short T(1 min) value and by the measurements of the J(HD) in the [Ru](eta2-HD) isotopomers. From T(1 min) and J(HD) values the H-H distances of the dihydrogen complexes were also calculated. A series of ruthenium complexes, [RuL(N-N)P3](BPh4)2 and [RuL(bpy)2P](BPh4)2 (P = P(OEt)3; L = H2O, CO, 4-CH3C6H4NC, CH3CN, 4-CH3C6H4CN, PPh(OEt)2], was prepared by substituting the labile eta2-H2 ligand in the 9, 10, 11 derivatives. The reactions of the new hydrides 4-6 and 8 with both mono- and bis(aryldiazonium) cations were studied and led to aryldiazene [Ru(C6H5N=NH)(N-N)P3](BPh4)2 (19, 21), [[Ru(N-N)P3]2(mu-4,4'-NH=NC6H4-C6H4N=NH)](BPh4)4 (20), and [Ru(C6H5N=NH)(bpy)2P](BPh4)2 (22) derivatives. Also the heteroallenes CO2 and CS2 reacted with [RuH(bpy)2P]BPh4, yielding the formato [Ru[eta1-OC(H)=O](bpy)2P]BPh4 and dithioformato [Ru[eta1-SC(H)=S](bpy)2P]BPh4 derivatives.     

C-H activation and C=C double bond formation reactions in iridium ortho-methyl arylphosphane complexes

The Vaska-type iridium(I) complex [IrCl(CO){PPh(2)(2-MeC(6)H(4))}(2)] (1), characterized by an X-ray diffraction study, was obtained from iridium(III) chloride hydrate and PPh(2)(2,6-MeRC(6)H(3)) with R=H in DMF, whereas for R=Me, activation of two ortho-methyl groups resulted in the biscyclometalated iridium(III) compound [IrCl(CO){PPh(2)(2,6-CH(2)MeC(6)H(3))}(2)] (2). Conversely, for R=Me the iridium(I) compound [IrCl(CO){PPh(2)(2,6-Me(2)C(6)H(3))}(2)] (3) can be obtained by treatment of [IrCl(COE)(2)](2) (COE=cyclooctene) with carbon monoxide and the phosphane in acetonitrile. Compound 3 in CH(2)Cl(2) undergoes intramolecular C-H oxidative addition, affording the cyclometalated hydride iridium(III) species [IrHCl(CO){PPh(2)(2,6-CH(2)MeC(6)H(3))}{PPh(2)(2,6-Me(2)C(6)H(3))}] (4). Treatment of 2 with Na[BAr(f) (4)] (Ar(f)=3,5-C(6)H(3)(CF(3))(2)) gives the fluxional cationic 16-electron complex [Ir(CO){PPh(2)(2,6-CH(2)MeC(6)H(3))}(2)][BAr(f) (4)] (5), which reversibly reacts with dihydrogen to afford the delta-agostic complex [IrH(CO){PPh(2)(2,6-CH(2)MeC(6)H(3))}{PPh(2)(2,6-Me(2)C(6)H(3))}][BAr(f)(4)] (6), through cleavage of an Ir-C bond. This species can also be formed by treatment of 4 with Na[BAr(f)(4)] or of 2 with Na[BAr(f)(4)] through C-H oxidative addition of one ortho-methyl group, via a transient 14-electron iridium(I) complex. Heating of the coordinatively unsaturated biscyclometalated species 5 in toluene gives the trans-dihydride iridium(III) complex [IrH(2)(CO){PPh(2)(2,6-MeC(6)H(3)CH=CHC(6)H(3)Me-2,6)PPh(2)}][BAr(f) (4)] (7), containing a trans-stilbene-type terdentate ligand, as result of a dehydrogenative carbon-carbon double bond coupling reaction, possibly through an iridium carbene species.     

Formation of a cyclobutylidene ring: intramolecular [2 + 2] cycloaddition of allyl and vinylidene C=C bonds under mild conditions

Intramolecular [2 + 2] cycloaddition of two C=C bonds in vinylidene complexes [Ru(eta5-C9H7){=C=C(R)H}(PPh3){kappa1-(P)-PPh2(C3H5)][BF4] affords cyclobutylidene complexes [Ru(eta5-C9H7){kappa2-(P,C)-(=CC(R)HCH2CHCH2PPh2)}(PPh3)][BF4], which can be also obtained by reaction of terminal alkynes with [Ru(eta5-C9H7)(PPh3){kappa3-(P,C,C)-PPh2(C3H5)}][PF6]. The reaction proceeds under mild conditions via vinylidene complexes, and the activation parameters were determined by kinetic studies.     

Diazo complexes of rhenium: preparations and crystal structures of the bis(dinitrogen), [Re(N2)2(PPh(OEt)2)4][BPh4] and methyldiazenido [ReCl(CH3N2)(CH3NHNH2)(PPh(OEt)2)3][BPh4] derivatives

Depending on experimental conditions and the nature of the hydrazine, the reactions of ReCl3P3 [P = PPh(OEt)2] with RNHNH2 (R = H, CH3, tBu) afford the bis(dinitrogen) [Re(N2)2P4]+ (2+), dinitrogen ReClN2P4 (3), and methyldiazenido [ReCl(CH3N2)(CH3NHNH2)P3]+ (1+) derivatives. In contrast, reactions of ReCl3P3 [P = PPh(OEt)2, PPh2OEt] with arylhydrazines ArNHNH2 (Ar = Ph, p-tolyl) give the aryldiazenido cations [ReCl(ArN2)(ArNHNH2)P3]+ (4+) and [ReCl(ArN2)P4]+ (7+) and the bis(aryldiazenido) cations [Re(ArN2)2P3]+ (5+, 6+). These complexes were characterized spectroscopically (IR; 1H and 31P NMR), and the BPh4 complexes 1, 2, and 7 were characterized crystallographically. The methyldiazenido derivative [ReCl(CH3N2)(CH3NHNH2)(PPh(OEt)2)3][BPh4] (1) crystallizes in space group P1 with a = 15.396(5) A, b = 16.986(5) A, c = 11.560(5) A, alpha = 93.96(5) degrees, beta = 93.99(5) degrees, gamma = 93.09(5) degrees, and Z = 2 and contains a singly bent CH3N2, group bonded to an octahedral central metal. One methylhydrazine ligand, one Cl- trans to the CH3N2, and three PPh(OEt)2 ligands complete the coordination. The complex [Re(N2)2(PPh(OEt)2)4][BPh4] (2) crystallizes in space group Pbaa with a = 23.008(5) A, b = 23.367(5) A, c = 12.863(3) A, and Z = 4. The structure displays octahedral coordination with two end-on N2 ligands in mutually trans positions. [ReCl(PhN2)(PPh(OEt)2)4][BPh4] (7) crystallizes in space group P2(1)/n with a = 19.613(5) A, b = 20.101(5) A, c = 19.918(5) A, beta = 115.12(2) degrees, and Z = 4. The structure shows a singly bent phenyldiazenido group trans to the Cl- ligand in an octahedral environment. The dinitrogen complex ReClN2P4 (3) reacts with CF3SO3CH3 to give the unstable methyldiazenido derivative [ReCl(CH3N2)P4][BPh4]. Reaction of the methylhydrazine complex [ReCl(CH3N2)(CH3NHNH2)P3][BPh4] (1) with Pb(OAc)4 at -30 degrees C results in selective oxidation of the hydrazine, affording the corresponding methyldiazene derivative [ReCl(CH3N=NH)(CH3N2)P3][BPh4] (8). In contrast, treatment with Pb(OAc)4 of the related arylhydrazines [ReCl(ArN2)(ArNHNH2)P3][BPh4] (4) [P = PPh(OEt)2] gives the bis(aryldiazenido) complexes [Re(ArN2)2P3][BPh4] (5). Possible protonation reactions of Br?nsted acids HX with all diazenides, 1, 4, 5, 6, and 8, were investigated and found to proceed only in the cases of the bis(aryldiazenido) complexes 5 and 6, affording, with HCl, the octahedral [ReCl(ArN=NH)(ArN2)P3][BPh4] or [ReCl(Ar(H)NN)(ArN2)P3][BPh4] (10) (Ar = Ph; P = PPh2OEt) derivative.     

Preparation and reactivity of mixed-ligand iron(II) hydride complexes with phosphites and polypyridyls

Hydride complexes [FeH(N-N)P3]BPh4 (1, 2) [N-N = 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen); P = P(OEt)4, PPh(OEt)2, and PPh2OEt] were prepared by allowing FeCl2(N-N) to react with phosphite in the presence of NaBH4. The hydrides [FeH(bpy)2P]BPh4 (3) [P = P(OEt)3 and PPh(OEt)2] were prepared by reacting the tris(2,2'-bipyridine) [Fe(bpy)3]Cl2.5H2O complex with the appropriate phosphite in the presence of NaBH4. The protonation reaction of 1 and 2 with acid was studied and led to thermally unstable (above -20 degrees C) dihydrogen [Fe(eta2-H2)(N-N)P3]2+ (4, 5) derivatives. The presence of the H2 ligand is indicated by short T(1 min) values (3.1-3.6 ms) and by J(HD) measurements (31.2-32.5 Hz) of the partially deuterated derivatives. Carbonyl [Fe(CO)(bpy)[P(OEt)3]3](BPh4)2 (6) and nitrile [Fe(CH3CN)(N-N)P3](BPh4)2 (7, 8) [N-N = bpy, phen; P = P(OEt)3 and PPh(OEt)2] complexes were prepared by substituting the H2 ligand in the eta2-H2 4, 5 derivatives. Aryldiazene complexes [Fe(ArN=NH)(N-N)P3](BPh4)2 (9, 10, 11) (Ar = C6H5, 4-CH3C6H4) were also obtained by allowing hydride [FeH(N-N)P3]BPh4 derivatives to react with aryldiazonium cations in CH2Cl2 at low temperature.     

Si-H and Si-Si activation at Pt: synthesis and reactivity of neutral and cationic silyl complexes

Reactions of [Pt(PEt(3))(3)] (1) with the silanes HSiPh(3), HSiPh(2)Me and HSi(OEt)(3) led to the products of oxidative addition, cis-[Pt(H)(SiPh(3))(PEt(3))(2)] (2), cis-[Pt(H)(SiPh(2)Me)(PEt(3))(2)] (3), cis-[Pt(H){Si(OEt)(3)}(PEt(3))(2)] (cis-4) and trans-[Pt(H){Si(OEt)(3)}(PEt(3))(2)] (trans-4). The complexes cis-4 and trans-4 can also be generated by hydrogenolysis of (EtO)(3)SiSi(OEt)(3) in the presence of 1. Furthermore, the silyl compounds cis-4 and trans-4 react with B(C(6)F(5))(3) and CH(3)CN by hydride abstraction to give the cationic silyl complex trans-[Pt{Si(OEt)(3)}(NCCH(3))(PEt(3))(2)][HB(C(6)F(5))(3)] (8). In addition, the reactivity of the complexes cis-4, trans-4 and 8 towards alkenes and CO was studied using NMR experiments.     

Synthesis and characterization of triazenide and triazene complexes of ruthenium and osmium

Triazenide [M(eta2-1,3-ArNNNAr)P4]BPh4 [M = Ru, Os; Ar = Ph, p-tolyl; P = P(OMe)3, P(OEt)3, PPh(OEt)2] complexes were prepared by allowing triflate [M(kappa2-OTf)P4]OTf species to react first with 1,3-ArN=NN(H)Ar triazene and then with an excess of triethylamine. Alternatively, ruthenium triazenide [Ru(eta2-1,3-ArNNNAr)P4]BPh4 derivatives were obtained by reacting hydride [RuH(eta2-H2)P4]+ and RuH(kappa1-OTf)P4 compounds with 1,3-diaryltriazene. The complexes were characterized by spectroscopy and X-ray crystallography of the [Ru(eta2-1,3-PhNNNPh){P(OEt)3}4]BPh4 derivative. Hydride triazene [OsH(eta1-1,3-ArN=NN(H)Ar)P4]BPh4 [P = P(OEt)3, PPh(OEt)2; Ar = Ph, p-tolyl] and [RuH{eta1-1,3-p-tolyl-N=NN(H)-p-tolyl}{PPh(OEt)2}4]BPh4 derivatives were prepared by allowing kappa1-triflate MH(kappa1-OTf)P4 to react with 1,3-diaryltriazene. The [Os(kappa1-OTf){eta1-1,3-PhN=NN(H)Ph}{P(OEt)3}4]BPh4 intermediate was also obtained. Variable-temperature NMR studies were carried out using 15N-labeled triazene complexes prepared from the 1,3-Ph15N=N15N(H)Ph ligand. Osmium dihydrogen [OsH(eta2-H2)P4]BPh4 complexes [P = P(OEt)3, PPh(OEt)2] react with 1,3-ArN=NN(H)Ar triazene to give the hydride-diazene [OsH(ArN=NH)P4]BPh4 derivatives. The X-ray crystal structure determination of the [OsH(PhN=NH){PPh(OEt)2}4]BPh4 complex is reported. A reaction path to explain the formation of the diazene complexes is also reported.     

C-H activations at iridium(I) square-planar complexes promoted by a fifth ligand

In the presence of ligands such as acetonitrile, ethylene, or propylene, the Ir(I) complex [Ir(1,2,5,6-eta-C8H12)(NCMe)(PMe3)]BF4 (1) transforms into the Ir(III) derivatives [Ir(1-kappa-4,5,6-eta-C8H12)(NCMe)(L)(PMe3)]BF4 (L = NCMe, 2; eta2-C2H4, 3; eta2-C3H6, 4), respectively, through a sequence of C-H oxidative addition and insertion elementary steps. The rate of this transformation depends on the nature of L and, in the case of NCMe, the pseudo-first-order rate constants display a dependence upon ligand concentration suggesting the formation of five-coordinate reaction intermediates. A similar reaction between 1 and vinyl acetate affords the Ir(III) complex [Ir(1-kappa-4,5,6-eta-C8H12){kappa-O-eta2-OC(Me)OC2H3}(PMe3)]BF4 (7) via the isolable five-coordinate Ir(I) compound [Ir(1,2,5,6-eta-C8H12){kappa-O-eta2-OC(Me)OC2H3}(PMe3)]BF4 (6). DFT (B3LYP) calculations in model complexes show that reactions initiated by acetonitrile or ethylene five-coordinate adducts involve C-H oxidative addition transition states of lower energy than that found in the absence of these ligands. Key species in these ligand-assisted transformations are the distorted (nonsquare-planar) intermediates preceding the intramolecular C-H oxidative addition step, which are generated after release of one cyclooctadiene double bond from the five-coordinate species. The feasibility of this mechanism is also investigated for complexes [IrCl(L)(PiPr3)2] (L = eta2-C2H4, 27; eta2-C3H6, 28). In the presence of NCMe, these complexes afford the C-H activation products [IrClH(CH=CHR)(NCMe)(PiPr3)2] (R = H, 29; Me, 30) via the common cyclometalated intermediate [IrClH{kappa-P,C-P(iPr)2CH(CH3)CH2}(NCMe)(PiPr3)] (31). The most effective C-H oxidative addition mechanism seems to involve three-coordinate intermediates generated by photochemical release of the alkene ligand. However, in the absence of light, the reaction rates display dependences upon NCMe concentration again indicating the intermediacy of five-coordinate acetonitrile adducts.     

Tautomerization of methyldiazene to formaldehyde-hydrazone in ruthenium and osmium complexes

Mixed-ligand hydrazine complexes [M(CO)(RNHNH2)P4](BPh4)2 (1, 2) [M = Ru, Os; R = H, CH3, C6H5; P = P(OEt)3] with carbonyl and triethyl phosphite were prepared by allowing hydride [MH(CO)P4]BPh4 species to react first with HBF4.Et2O and then with hydrazines. Depending on the nature of the hydrazine ligand, the oxidation of [M(CO)(RNHNH2)P4](BPh4)2 derivatives with Pb(OAc)4 at -30 C gives acetate [M(kappa1-OCOCH3)(CO)P4]BPh4 (3a), phenyldiazene [M(CO)(C6H5N=NH)P4](BPh4)2 (3c, 4c), and methyldiazene [M(CO)(CH3N=NH)P4](BPh4)2 (3b, 4b) derivatives. Methyldiazene complexes 3b and 4b undergo base-catalyzed tautomerization of the CH3N=NH ligand to formaldehyde-hydrazone NH2N=CH2, giving the [M(CO)(NH2N=CH2)P4](BPh4)2 (5, 6) derivatives. Complexes 5 and 6 were characterized spectroscopically and by the X-ray crystal structure determination of the [Ru(CO)(NH2N=CH2)[P(OEt)3]4](BPh4)2 (5) derivative. Acetone-hydrazone [M(CO)[NH2N=C(CH3)2]P4](BPh4)2 (7, 8) complexes were also prepared by allowing hydrazine [M(CO)(NH2NH2)P4](BPh4)2 derivatives to react with acetone.     

The preparation and characterisation of hetero- and homobimetallic complexes containing bridging naphthalene-1,8-dithiolato ligands

Homo- and heterobimetallic complexes of the form [(PPh(3))(2)(mu(2)-1,8-S(2)-nap){ML(n)}] (in which (1,8-S(2)-nap)=naphtho-1,8-dithiolate and {ML(n)}={PtCl(2)} (1), {PtClMe} (2), {PtClPh} (3), {PtMe(2)} (4), {PtIMe(3)} (5) and {Mo(CO)(4)} (6)) were obtained by the addition of [PtCl(2)(NCPh)(2)], [PtClMe(cod)] (cod=1,5-cyclooctadiene), [PtClPh(cod)], [PtMe(2)(cod)], [{PtIMe(3)}(4)] and [Mo(CO)(4)(nbd)] (nbd=norbornadiene), respectively, to [Pt(PPh(3))(2)(1,8-S(2)-nap)]. Synthesis of cationic complexes was achieved by the addition of one or two equivalents of a halide abstractor, Ag[BF(4)] or Ag[ClO(4)], to [{Pt(mu-Cl)(mu-eta(2):eta(1)-C(3)H(5))}(4)], [{Pd(mu-Cl)(eta(3)-C(3)H(5))}(2)], [{IrCl(mu-Cl)(eta(5)-C(5)Me(5))}(2)] (in which C(5)Me(5)=Cp*=1,2,3,4,5-pentamethylcyclopentadienyl), [{RhCl(mu-Cl)(eta(5)-C(5)Me(5))}(2)], [PtCl(2)(PMe(2)Ph)(2)] and [{Rh(mu-Cl)(cod)}(2)] to give the appropriate coordinatively unsaturated species that, upon treatment with [(PPh(3))(2)Pt(1,8-S(2)-nap)], gave complexes of the form [(PPh(3))(2)(mu(2)-1,8-S(2)-nap){ML(n)}][X] (in which {ML(n)}[X]={Pt(eta(3)-C(3)H(5))}[ClO(4)] (7), {Pd(eta(3)-C(3)H(5))}[ClO(4)] (8), {IrCl(eta(5)-C(5)Me(5))}[ClO(4)] (9), {RhCl(eta(5)-C(5)Me(5))}[BF(4)] (10), {Pt(PMe(2)Ph)(2)}[ClO(4)](2) (11), {Rh(cod)}[ClO(4)] (12); the carbonyl complex {Rh(CO)(2)}[ClO(4)] (13) was formed by bubbling gaseous CO through a solution of 12. In all cases the naphtho-1,8-dithiolate ligand acts as a bridge between two metal centres to give a four-membered PtMS(2) ring (M=transition metal). All compounds were characterised spectroscopically. The X-ray structures of 5, 6, 7, 8, 10 and 12 reveal a binuclear PtMS(2) core with PtM distances ranging from 2.9630(8)-3.438(1) A for 8 and 5, respectively. The napS(2) mean plane is tilted with respect to the PtP(2)S(2) coordination plane, with dihedral angles in the range 49.7-76.1 degrees and the degree of tilting being related to the PtM distance and the coordination number of M. The sum of the Pt(1)coordination plane/napS(2) angle, a, and the Pt(1)coordination plane/M(2)coordination plane angle, b, a+b, is close to 120 degrees in nearly all cases. This suggests that electronic effects play a significant role in these binuclear systems.     

Rhodium/iridium-titanium azaheterometallocubanes

Treatment of [[Ti(eta5-C5Me5)(mu-NH)]3(mu3-N)] (1) with the diolefin complexes [[MCl(cod)]2] (M = Rh, Ir; cod = 1,5-cyclooctadiene) in toluene afforded the ionic complexes [M-(cod)(mu3-NH)3Ti3(eta5-C5Me5)3(mu3-N)]Cl [M = Rh (2), Ir (3)]. Reaction of complexes 2 and 3 with [Ag(BPh4)] in dichloromethane leads to anion metathesis and formation of the analogous ionic derivatives [M(cod)(mu3-NH)3Ti3-(eta5-C5Me5)3(mu3-N)][BPh4] [M = Rh (4), Ir (5)]. An X-ray crystal structure determination for 5 reveals a cube-type core [IrTi3N4] for the cationic fragment, in which 1 coordinates in a tripodal fashion to the iridium atom. Reaction of the diolefin complexes [[MCl(cod))2] (M = Rh, Ir) and [[RhCl(C2H4)2]2] with the lithium derivative [[Li(mu3-NH)2(mu3-N)-Ti3(eta5-C5Me5)3(mu3-N)]2] x C7H8 (6 C7H8) in toluene gave the neutral cube-type complexes [M(cod)(mu-NH)2(mu3-N)Ti3-(eta5-C5Me5)3(mu3-N)] [M = Rh (7), Ir (8)] and [Rh(C2H4)2(mu3-NH)2(mu3-N)Ti3(eta5-C5Me5)3(mu3-N)] (9), respectively. Density functional theory calculations have been carried out on the ionic and neutral azaheterometallocubane complexes to understand their electronic structures.     

Towards new organometallic wires: tetraruthenium complexes bridged by phenylenevinylene and vinylpyridine ligands

The tetranuclear complexes [{(PiPr(3))(2)(CO)ClRu(mu-CH=CHpy)Ru Cl(CO)(PPh(3))(2)}(2)(mu-CH=CH-C(6)H(4)- CH=CH-1,4)] (3 a) and [{(PiPr(3))(2)(CO)ClRu(mu-CH=CHpy)RuCl(CO)(PPh(3))(2)}(2)(mu-CH=CH-C(6)H(4)-CH=CH-1,3)] (3b), which contain vinylpyridine ligands that connect peripheral Ru(PiPr(3))(2)(CO)Cl units to a central divinylphenylene-bridged diruthenium core, have been prepared and investigated. These complexes, in various oxidation states up to the tetracation level, have been characterized by standard electrochemical and spectroelectrochemical techniques, including IR, UV/Vis/NIR and ESR spectroscopy. A comparison with the results for the vinylpyridine-bridged dinuclear complex [PiPr(3))(2)(CO)ClRu(mu-CH=CHpy)RuCl(CO)(PPh(3))(2)(CH=CHPh)] (6) and the divinylphenylene-bridged complexes [{(EtOOCpy)(CO)Cl(PPh(3))(2)Ru}(2)(mu-CH=CH-C(6)H(4)-CH=CH-1,4)] (8a) and [{(EtOOCpy)(CO)Cl(PPh(3))(2)Ru}(2)(mu-CH=CH-C(6)H(4)-CH=CH-1,3)] (8b), which represent the outer sections (6) or the inner core (8a,b) of complexes 3a,b, and with the mononuclear complex [(EtOOCpy)(CO)(PPh(3))(2)RuCl(CH=CHPh)] (7) indicate that every accessible oxidation process is primarily centred on one of the vinyl ligands, with smaller contributions from the metal centres. The experimental results and quantum chemical calculations indicate charge- and spin-delocalization across the central divinylphenylenediruthenium part of 3a,b or the styrylruthenium unit of 6, but not beyond. The energy gap between the higher lying styryl- or divinylphenylenediruthenium-based and the lower occupied vinylpyridineruthenium-based orbitals increases in the order 6<3 b<3 a and thus follows the conjugation within the non-heteroatom-substituted aromatic vinyl ligand.     

Preparation of five- and six-coordinate aryl(hydrido) iridium(III) complexes from benzene and functionalized arenes by C-H activation

The reaction of the in situ generated cyclooctene iridium(I) derivative trans-[IrCl(C8H14)(PiPr3)2] with benzene at 80 degrees C gave a mixture of the five-coordinate dihydrido and hydrido(phenyl) iridium(III) complexes [IrH2(Cl)(PiPr3)2] 2 and [IrH(C6H5)(Cl)(PiPr3)2] 3 in the ratio of about 1 : 2. The chloro- and fluoro-substituted arenes C6H5X (X = Cl, F), C6H4F2 and C6H4F(CH3) reacted also by C-H activation to afford the corresponding aryl(hydrido) iridium(III) derivatives [IrH(C6H4X)(Cl)(PiPr3)2] 7, 8, [IrH(C6H3F2)(Cl)(PiPr3)2] 9-11 and [IrH[C6H3F(CH3)](Cl)(PiPr3)2] 12, 13, respectively. The formation of isomeric mixtures had been detected by 1H, 13C, 19F and 31P NMR spectroscopy. Treatment of 3 and 7-13 with CO gave the octahedral carbonyl iridium(III) complexes [IrH(C6H3XX')(Cl)(CO)(PiPr3)2] 5, 14-20 without the elimination of the arene. The reactions of trans-[IrCl(C8H14)(PiPr3)2] with aryl ketones C6H5C(O)R (R = Me, Ph), aryl ketoximes C6H5C(NOH)R (R = Me, Ph) and benzaloxime C6H5C(NOH)H resulted in the formation of six-coordinate aryl(hydrido) iridium(III) compounds 21-25 with the aryl ligand coordinated in a bidentate kappa2-C,O or kappa2-C,N fashion. With C6H5C(O)NH2 as the substrate, the two isomers [IrH[kappa2-N,O-NHC(O)C6H5](Cl)(PiPr3)2] 26 and [IrH[kappa2-C,O-C6H4C(O)NH2](Cl)(PiPr3)2] 27 were prepared stepwise. Treatment of trans-[IrCl(C8H14)(PiPr3)2] with benzoic acid gave the benzoato(hydrido) complex [IrH[kappa2-O,O-O2CC6H5](Cl)(PiPr3)2] 29 which did not rearrange to the kappa2-C,O isomer.     

Versatility of dithiophosphates in the syntheses of copper(I) complexes with bis(diphenylphosphino)alkanes: abstraction of chloride from dichloromethane

Reactions of [Cu(CH(3)CN)(4)]X (X = PF(6), BF(4)) with bis(diphenylphosphino)methane (dppm = Ph(2)PCH(2)PPh(2)) and ammonium dialkyldithiophosphates, (NH(4))[S(2)P(OR)(2)] (R = Et, (i)Pr), yield a series of novel Cu(I) polynuclear complexes, trinuclear [Cu(3)(mu-dppm)(3)(mu(3)-Cl){S(2)P(OEt)(2)}] (PF(6)) 1 and [Cu(3)(mu-dppm)(2){S(2)P(OR)(2)}(2)](PF(6)) (R = Et, 2; (i)Pr, 3), tetranuclear [Cu(4)(mu-dppm)(2) {S(2)P(OEt)(2)}(4)] 4, and hexanuclear [Cu(6)(mu-dppm)(2)(mu(4)-Cl){S(2)P(O(i)()Pr)(2)}(4)](BF(4)) 5. Similarly, the reaction of [Cu(2)(mu-L-L)(2)(CH(3)CN)(2)](PF(6))(2) (L-L, dppm, dppe = Ph(2)PCH(2)CH(2)PPh(2)) with (NH(4))[S(2)P(OR)(2)] yields dinuclear [Cu(2)(mu-dppm)(2){S(2)P(OR)(2)}(2)] 6 (R= (i)Pr, 6A; Et, 6B), trinuclear [Cu(3)(mu-dppe)(3)(mu-Cl)(2){S(2)P(O(i)Pr)(2)}] 9, and polymeric [Cu(mu(2)-dppe){S(2)P(OR)(2)}](n) (R = Et, 7; (i)Pr, 8) complexes. The formation of 1 and 5 involved the abstraction of chloride from dichloromethane when the Cu/S(2)P(OR)(2) ratio exceeded 1, but when ratio was 1:1, no Cl abstraction occurred, as in compound 4. Compound 9, however, was obtained as a 12% byproduct in the synthesis of 8 using a 1:1:1 ratio of Cu/dppe/S(2)P(O(i)Pr)(2). The chloride binds to Cu atoms in a mu(3)-Cl mode by capping one face of the Cu(3) triangle of cluster 1. A mu(4)-Cl caps a single tetragonal face of the trigonal prism of cluster 5, and in the cluster 9, two chlorides bond in mu(2)-Cl modes. Both clusters 2 and 3 exhibit the mu(3)-S mode of bonding for dtp ligands. Only cluster 5 exhibited close Cu...Cu contacts (2.997-3.0238 A). All of compounds were characterized by single-crystal X-ray diffraction and pertinent crystallographic data for 1, 5, and 9 are are follows: (1) C(79)H(76)ClCu(3)F(6)O(2)P(8)S(2), triclinic, P, a = 11.213(1) A, b = 14.142(1) A, c = 25.910(2) A, alpha = 95.328(2) degrees , beta = 99.594(2) degrees , gamma = 102.581(2) degrees , V = 3918.2(6) A(3), Z = 2; (5) C(74)H(100)BClCu(6)F(4)O(8)P(8)S(8), monoclinic, P2(1)/n, a = 25.198(4) A, b = 15.990(3) A, c = 25.421(4) A, beta = 106.027(3) degrees , V = 9845(3)A(3), Z = 4; (9) C(84)H(86)Cl(2)Cu(3)O(2)P(7)S(2), monoclinic, C2/c, with a = 24.965(3) A, b = 17.058(2) A, c = 20.253(2) A, beta = 95.351(4) degrees , V = 8587.4(17)A(3), Z = 4.     

Preparation and characterization of an isometallabenzene with the structure of a 1,2,4-cyclohexatriene

The elongated dihydrogen complex [Os{C6H4C(O) CH3}(eta2-H2)(H2O)(PiPr3)2]BF4 reacts with phenylacetylene and HBF4.OEt2 to give the unsaturated compound [Os{(E)-CH=CHPh}(CCPh)(CCH2Ph)(PiPr3)2]BF4 containing alkenyl, alkynyl, and carbyne ligands. The addition of sodium chloride to this compound leads to the cyclic allene Os{=C=C(Ph)CH(Ph)CH=C(CH2Ph)}Cl(PiPr3)2, which is the first isometallabenzene with the structure of a 1,2,4-cyclohexatriene.     

Synthesis, characterisation and molecular structure of Re(III) 2-oxacyclocarbenes stabilised by a benzoyldiazenido ligand

A family of new Fischer-type rhenium(III) benzoyldiazenido-2-oxacyclocarbenes of formula [(ReCl2[eta1-N2C(O)Ph][=C(CH2)nCH(R)O](PPh3)2][n = 2, R = H (2), R = Me (3); n = 3, R = H (4), R = Me (5)] have been prepared by reaction of [ReCl2[eta2-N2C(Ph)O](PPh3)2] (1) with omega-alkynols, such as 3-butyn-1-ol, 4-pentyn-1-ol, 4-pentyn-2-ol, 5-hexyn-2-ol in refluxing THF. The correct formulation of the carbene derivatives 2-5 has been unambiguously determined in solution by NMR analysis and confirmed for compounds 2-4 by X-ray diffraction methods in the solid state. All complexes are octahedral with the benzoyldiazenido ligand, Re[N2C(O)Ph], adopting a "single bent" conformation. The coordination basal plane is completed by an oxacyclocarbene ligand and two chlorine atoms. Two triphenylphosphines in trans positions with respect to each other complete the octahedral geometry around rhenium. The reactivity of 1 towards different alkynes and alkenes including propargyl- and allylamine has been also studied. With propargyl amine, monosubstituted or bisubstituted complexes, [(ReCl2[eta1-N2C(O)Ph][eta1-NH2CH2C triple bond CH]n(PPh3)(3-n)][n= 1 (6); n = 2 (7)], have been isolated depending on the reaction conditions. In contrast, the reaction with allylamine gave only the disubstituted complex [(ReCl2[eta1-N2C(O)Ph][eta1-NH2CH2CH=CH2]2(PPh3)] (8). The molecular structure of the monosubstituted adduct has been confirmed by X-ray analysis in the solid state.     

Binuclear half-sandwich cobalt(III) and rhodium(III) ortho-carboranedichalocogenolato complexes with ether chain-bridged bis(cyclopentadienyl) ligand

1, 1'-(3-Oxapentamethylene)dicyclopentadiene [O(CH(2)CH(2)C(5)H(5))(2)], containing a flexible chain-bridged group, was synthesized by the reaction of sodium cyclopentadienide with bis(2-chloroethyl) ether through a slightly modified literature procedure. Furthermore, the binuclear cobalt(III) complex O[CH(2)CH(2)(eta(5)-C(5)H(4))Co(CO)I(2)](2) and insoluble polynuclear rhodium(III) complex {O[CH(2)CH(2)(eta(5)-C(5)H(4))RhI(2)](2)}(n) were obtained from reactions of with the corresponding metal fragments and they react easily with PPh(3) to give binuclear metal complexes, O[CH(2)CH(2)(eta(5)-C(5)H(4))Co(PPh(3))I(2)](2) and O[CH(2)CH(2)(eta(5)-C(5)H(4))Rh(PPh(3))I(2)](2), respectively. Complexes react with bidentate dilithium dichalcogenolato ortho-carborane to give eight binuclear half-sandwich ortho-carboranedichalcogenolato cobalt(III) and rhodium(III) complexes O[CH(2)CH(2)(eta(5)-C(5)H(4))Co(PPh(3))(E(2)C(2)B(10)H(10))](2) (E = S and Se), O[CH(2)CH(2)(eta(5)-C(5)H(4))](2)Co(2)(E(2)C(2)B(10)H(10)) (E = S and Se), O[CH(2)CH(2)(eta(5)-C(5)H(4))Co(E(2)C(2)B(10)H(10))](2) (E = S and Se and O[CH(2)CH(2)(eta(5)-C(5)H(4))Rh(PPh(3))(E(2)C(2)B(10)H(10))](2) (E = S and Se). All complexes have been characterized by elemental analyses, NMR spectra ((1)H, (13)C, (31)P and (11)B NMR) and IR spectroscopy. The molecular structures were determined by X-ray diffractometry.     

Preparation and reactivity of penta- and tetracoordinate platinum(II) hydride complexes with P(OEt)3 and PPh(OEt)2 phosphite ligands

The pentacoordinate [PtH{P(OEt)3}4]BF4 (1) hydride complex was prepared by allowing the tetrakis(phosphite) Pt{P(OEt)3}4 to react with HBF4.Et2O at -80 degrees C. Depending on the nature of the acid used, however, the protonation of the related Pt{PPh(OEt)2}4 complex yielded the pentacoordinate [PtH{PPh(OEt)2}4]BF4 (3) or the tetracoordinate [PtH{PPh(OEt)2}3]Y (4) [Y = BF4- (a), CF3SO3- (b), Cl- (c)] derivatives. Neutral PtHClP2 (7,8) [P = P(OEt)3, PPh(OEt)2] hydride complexes were prepared by allowing PtCl2P2 to react with NaBH4 in CH3CN. The tetrakis(phosphite)[Pt{P(OEt)3}4](BF4)2 (2) derivative was also synthesised and then characterised spectroscopically and by an X-ray crystal structure determination. Reactivity with aryldiazonium cations of all the hydrides was investigated and found to proceed only with the PtHClP2 complex to yield the aryldiazene [PtCl(ArN=NH)P2]BF4[P = PPh(OEt)2] derivative. The hydrazine [PtCl(NH2NH2){PPh(OEt)2}2]BPh4 complex was also prepared by allowing PtHClP2 to react first with AgCF3SO3 and then with hydrazine.