Synthesis, structure and reactivity of novel pyridazine-coordinated diiron bridging carbene complexes

[{mu-(Pyridazine-N(1):N(2))}Fe(2)(mu-CO)(CO)(6)](1) reacts with aryllithium reagents, ArLi (Ar = C(6)H(5), m-CH(3)C(6)H(4)) followed by treatment with Me(3)SiCl to give the novel pyridazine-coordinated diiron bridging siloxycarbene complexes [(C(4)H(4)N(2))Fe(2){mu-C(OSiMe(3))Ar}(CO)(6)](2, Ar = C(6)H(5); 3, Ar =m-CH(3)C(6)H(4)). Complex 2 reacts with HBF(4).Et(2)O at low temperature to yield a cationic bridging carbyne complex [(C(4)H(4)N(2))Fe(2)(mu-CC(6)H(5))(CO)(6)]BF(4)(4). Cationic 4 reacts with NaBH(4) in THF at low temperature to afford the diiron bridging arylcarbene complex [(C(4)H(4)N(2))Fe(2){mu-C(H)C(6)H(5)}(CO)(6)](5). Unexpectedly, the reaction of 4 with NaSCH(3) under similar conditions gave the bridging arylcarbene complex 5 and a carbonyl-coordinated diiron bridging carbene complex [Fe(2){mu-C(SCH(3))C(6)H(5)}(CO)(7)](6), while the reaction of NaSC(6)H(4)CH(3)-p with 4 affords the expected bridging arylthiocarbene complex [(C(4)H(4)N(2))Fe(2){mu-C(SC(6)H(4)CH(3)-p)C(6)H(5)}(CO)(6)](7), which can be converted into a novel diiron bridging carbyne complex with a thiolato-bridged ligand, [Fe(2)(mu-CC(6)H(5))(mu-SC(6)H(4)CH(3)-p)(CO)(6)](8). Cationic can also react with the carbonylmetal anionic compound Na(2)[Fe(CO)(4)] to yield complex 5, while the reactions of 4 with carbonylmetal anionic compounds Na[M(CO)(5)(CN)](M = Cr, Mo, W) produce the diiron bridging aryl(pentacarbonylcyanometal)carbene complexes [(C(4)H(4)N(2))Fe(2)-{mu-C(C(6)H(5))NCM(CO)(5)}(CO)(6)](9, M = Cr; 10, M = Mo; 11, M = W). The structures of complexes 2, 5, 6, 8, and 9 have been established by X-ray diffraction studies.     

Novel dimetal bridging carbene complexes derived from a terminal carbonyl dimetal compound. Syntheses, structures and reactivities of 7H-indene-coordinated diiron bridging carbene complexes

Pentacarbonyl-7H-indenediiron, [Fe2(CO)5(eta3,eta5-C9H8)] (1), reacts with aryllithium, ArLi (Ar = C6H5, p-C6H5C6H4), followed by alkylation with Et3OBF4 to give novel 7H-indene-coordinated diiron bridging alkoxycarbene complexes [Fe2{mu-C(OC2H5)Ar}(CO)4(eta4,eta4-C9H8)] (2, Ar = C6H5; 3, Ar = p-C6H5C6H4). Complexes 2 and 3 react with HBF4.Et2O at low temperature to yield cationic bridging carbyne complexes [Fe2(mu-CAr)(CO)4(eta4,eta4-C9H8)]BF4 (4, Ar = C6H5; 5, Ar = p-C6H5C6H4). Cationic 4 and 5 react with NaBH4 in THF at low temperature to afford diiron bridging arylcarbene complexes [Fe2{mu-C(H)Ar}(CO)4(eta4,eta4-C9H8)] (6, Ar = C6H5; 7, Ar = p-C6H5C6H4). The similar reactions of 4 and 5 with NaSC6H4CH3-p produce the bridging arylthiocarbene complexes [Fe2{mu-C(Ar)SC6H4CH3-p}(CO)4(eta4,eta4-C9H8)] (8, Ar = C6H5; 9, Ar = p-C6H5C6H4). Cationic 4 and 5 can also react with anionic carbonylmetal compounds Na[M(CO)5(CN)] (M = Cr, Mo, W) to give the diiron bridging aryl(pentacarbonylcyanometal)carbene complexes [Fe2{mu-C(Ar)NCM(CO)5}(CO)4(eta4,eta4-C9H8)] (10, Ar = C6H5, M = Cr; 11, Ar = p-C6H5C6H4, M = Cr; 12, Ar = C6H5, M = Mo; 13, Ar = p-C6H5C6H4, M = Mo; 14, Ar = C6H5, M = W; 15, Ar = p-C6H5C6H4, M = W). Interestingly, in CH2Cl2 solution at room temperature complexes 10-15 were transformed into the isomerized 7H-indene-coordinated monoiron complexes [Fe(CO)2(eta5-C9H8)C(Ar)NCM(CO)5] (16, Ar = C6H5, M = Cr; 17, Ar = p-C6H5C6H4, M = Cr; 18, Ar = C6H5, M = Mo; 19, Ar = p-C6H5C6H4, M = Mo; 20, Ar = C6H5, M = W; 21, Ar = p-C6H5C6H4, M = W), while complex 3 was converted into a novel ring addition product [Fe2{C(OC2H5)C6H4C6H5-p-(eta2,eta5-C9H8)}(CO)5] (22) under the same conditions. The structures of complexes 2, 6, 8, 14, 18 and 22 have been established by X-ray diffraction studies.     

Small Heteroborane Cluster Systems. 6. Mössbauer Effect Study of Iron Substituted Small Metallaborane Clusters

The M?ssbauer effect spectra for a series of small [Fe(eta(5)-C(5)H(5))(CO)(x)()] substituted metallaborane complexes are reported, where x = 1 or 2. The pentaborane cage in compounds [Fe(eta(5)-C(5)H(5))(CO)(2)B(5)H(7)P(C(6)H(5))(2)] (1), [Fe(eta(5)-C(5)H(5))(CO)(2)B(5)H(8)] (2), and [(Fe(eta(5)-C(5)H(5))(CO)(2))(2)B(5)H(7)] (3) was found to act as a significantly better donor ligand than the ligands in a comparison group of previously reported [Fe(eta(5)-C(5)H(5))(CO)LX] complexes, where L = CO or PPh(3) and X = halide, pseudohalide, or alkyl ligands. These metallaborane complexes were found to most resemble their silyl analogues in M?ssbauer spectral parameters and the electronic distribution around the iron centers. In addition, the M?ssbauer data showed that the [&mgr;-2,3-(P(C(6)H(5))(2)B(5)H(7)](-) ligand was a superior donor to the corresponding unsubstituted [B(5)H(8)](-) ligand. The M?ssbauer spectral results for the metallaborane complexes studied were found to be in general agreement with the anticipated donor and accepting bonding considerations for the cage ligands based upon their infrared and (11)B NMR spectra and X-ray structural features. The M?ssbauer data for the [Fe(eta(5)-C(5)H(5))(CO)B(4)H(6)(P(C(6)H(5))(2))] (4) and [Fe(eta(5)-C(5)H(5))(CO)B(3)H(7)(P(C(6)H(5))(2))] (5) complexes, in comparison with compound 1, showed that as the borane cage becomes progressively smaller, it becomes a poorer donor ligand. A qualitative relationship was found between the observed M?ssbauer isomer shift data and the number of boron cage vertices for the structurally related [Fe(eta(5)-C(5)H(5))(CO)(x)B(y)H(z)P(C(6)H(5))(2)] complexes, where x = 1 or 2, y = 3-5, and z = 6 or 7. The X-ray crystallographic data for compounds 1, 2, 5, and [Fe(eta(5)-C(5)H(5))(CO)B(5)H(8)] (6) were also found to agree with the trends observed in the M?ssbauer spectra which showed that the s-electron density on the iron nucleus increases in the order 5 < 6 < 2 < 1. The X-ray crystal structure of complex 2 is also reported. Crystallographic data for 2: space group P2(1)/c (No. 14, monoclinic), a = 6.084(3) ?, b = 15.045(8) ?, c = 13.449(7) ?, beta = 99.69(5) degrees, V = 1213(1) ?(3), Z = 4 molecules/cell.     

Remarkable reactions of cyclooctatetraene diiron-bridging carbyne complexes with amino and amido compounds: nucleophilic addition to and breaking of the cyclooctatetraene ring

The reactions of the cationic, diiron-bridging carbyne complexes [Fe(2)(mu-CAr)(CO)(4)(eta(8)-C(8)H(8))]BF(4) (1, Ar=C(6)H(5); 2, Ar=p-CH(3)C(6)H(4); 3, Ar=p-CF(3)C(6)H(4)) with LiN(C(6)H(5))(2) in THF at low temperature gave novel N-nucleophilic-addition products, namely, the neutral, diiron-bridging carbyne complexes [Fe(2)(mu-CAr)(CO)(4)(eta(7)-C(8)H(8)N(C(6)H(5))(2))] (4, Ar=C(6)H(5); 5, Ar=p-CH(3)C(6)H(4); 6, Ar=p-CF(3)C(6)H(4))). Cationic bridging carbyne complexes 1-3 react with (C(2)H(5))(2)NH, (iC(3)H(7))(2)NH, and (C(6)H(11))(2)NH under the same conditions with ring cleavage of the COT ligand to produce the novel diiron-bridging carbene inner salts [Fe(2)[mu-C(Ar)C(8)H(8)NR(2)](CO)(4)] (7, Ar=C(6)H(5), R=C(2)H(5); 8, Ar=p-CH(3)C(6)H(4), R=C(2)H(5); 9, Ar=p-CF(3)C(6)H(4), R=C(2)H(5); 10, Ar=C(6)H(5), R=iC(3)H(7); 11, Ar=p-CH(3)C(6)H(4), R=iC(3)H(7); 12, Ar=p-CF(3)C(6)H(4), R=iC(3)H(7); 13, Ar=C(6)H(5), R=C(6)H(11); 14, Ar=p-CH(3)C(6)H(4), R=C(6)H(11), 15, Ar=p-CF(3)C(6)H(4), R=C(6)H(11)). Piperidine reacts similarly with cationic carbyne complex 3 to afford the corresponding bridging carbene inner salt [Fe(2)[mu-C(Ar)C(8)H(8)N(CH(2))(5)](CO)(4)] (16). Compound 9 was transformed into a new diiron-bridging carbene inner salt 17, the trans isomer of 9, by heating in benzene. Unexpectedly, the reaction of C(6)H(5)NH(2) with 2 gave a novel COT iron-carbene complex [Fe(2)[=C(C(6)H(4)CH(3)-p)NHC(6)H(5)](mu-CO)(CO)(3)(eta(8)-C(8)H(8))] (18). However, the analogous reactions of 2-naphthylamine with 2 and of p-CF(3)C(6)H(4)NH(2) with 3 produce novel chelated iron-carbene complexes [Fe(2)[=C(C(6)H(4)CH(3)-p)NC(10)H(7)](CO)(4)(eta(2):eta(3):eta(2)-C(8)H(9))] (19) and [Fe(2)[=C(C(6)H(4)CF(3)-p)NC(6)H(4)CF(3)-p](CO)(4)(eta(2):eta(3):eta(2)-C(8)H(9))] (20), respectively. Compound 18 can also be transformed into the analogous chelated iron-carbene complex [Fe(2)[=C(C(6)H(4)CH(3)-p)NC(6)H(5)](CO)(4)(eta(2):eta(3):eta(2)-C(8)H(9))] (21). The structures of complexes 6, 9, 15, 17, 18, and 21 have been established by X-ray diffraction studies.     

Highly bulky and electron-rich terminal ruthenium phosphido complexes: new donor ligands for palladium-catalyzed suzuki cross-couplings

Secondary phosphine complexes of the formula [(eta(5)-C(5)H(5))Ru(L)(2)(PHR(2))](+) BAr(F)(-) are prepared from cationic ruthenium N(2) complexes and PHR(2) (R = Ph (a), t-Bu (b), Cy (c)). Additions of t-BuOK or NaN(SiMe(3))(2) give the phosphido complexes (eta(5)-C(5)H(5))Ru(L)(2)(PR(2)) ((L)(2) = (PEt(3))(2) (5a-c), depe (6a,b)) in high NMR yields. These rapidly oxidize in air to give isolable RuP(=O)R(2) species. Complex 5a is more basic than the rhenium analogue (eta(5)-C(5)H(5))Re(NO)(PPh(3))(PPh(2)), and 6b is more basic than P-t-Bu(3). Complexes 5a-c and 6b are effective ligands for palladium-catalyzed Suzuki reactions. The catalyst from 6b is nearly as reactive as that from the benchmark ligand P-t-Bu(3).     

Acetylide-bridged organometallic oligomers via the photochemical metathesis of methyl-iron(II) complexes

The acetylido methyl iron(II) complexes, cis/trans-[Fe(dmpe)(2)(C[triple bond]CR)(CH(3))] (1) and trans-[Fe(depe)(2)(C[triple bond]CR)(CH(3))] (2) (dmpe = 1,2-dimethylphoshinoethane; depe = 1,2-diethylphosphinoethane), were synthesized by transmetalation from the corresponding alkyl halide complexes. Acetylido methyl iron(II) complexes were also formed by transmetalation from the chloride complexes, trans-[Fe(dmpe)(2)(C[triple bond]CR)(Cl)] or trans-[Fe(depe)(2)(C[triple bond]CR)(Cl)]. The structure of trans-[Fe(dmpe)(2)(C[triple bond]CC(6)H(5))(CH(3))] (1a) was determined by single-crystal X-ray diffraction. The methyl acetylido iron complexes, [Fe(dmpe)(2)(C[triple bond]CR)(CH(3))] (1), are thermally stable in the presence of acetylenes; however, under UV irradiation, methane is lost with the formation of a metal bisacetylide. Photochemical metathesis of cis- or trans-[Fe(dmpe)(2)(CH(3))(C[triple bond]CR)] (R = C(6)H(5) (1a), 4-C(6)H(4)OCH(3) (1b)) with terminal acetylenes was used to selectively synthesize unsymmetrically substituted iron(II) bisacetylide complexes of the type trans-[Fe(dmpe)(2)(C[triple bond]CR)(C[triple bond]CR')] [R = Ph, R' = Ph (6a), 4-CH(3)OC(6)H(4) (6b), (t)()Bu (6c), Si(CH(3))(3) (6d), (CH(2))(4)C[triple bond]CH (6e); R = 4-CH(3)OC(6)H(4), R' = 4-CH(3)OC(6)H(4), (6g), (t)()Bu (6h), (CH(2))(4)C[triple bond]CH (6i), adamantyl (6j)]. The structure of the unsymmetrical iron(II) bisacetylide complex trans-[Fe(dmpe)(2)(C[triple bond]CC(6)H(5))(C[triple bond]CC(6)H(4)OCH(3))] (6b) was determined by single-crystal X-ray diffraction. The photochemical metathesis of the bis-acetylene, 1,7-octadiyne, with trans-[Fe(dmpe)(2)(CH(3))(C[triple bond]CPh)] (1a), was utilized to synthesize the bridged binuclear species trans,trans-[(C(6)H(5)C[triple bond]C)Fe(dmpe)(2)(mu-C[triple bond]C(CH(2))(4)C[triple bond]C)Fe(dmpe)(2)(C[triple bond]CC(6)H(5))] (11). The trinuclear species trans,trans,trans-[(C(6)H(5)C[triple bond]C)Fe(dmpe)(2)(mu-C[triple bond]C(CH(2))(4)C[triple bond]C)Fe(dmpe)(2)(mu-C[triple bond]C(CH(2))(4)C[triple bond]C)Fe(dmpe)(2)(C[triple bond]CC(6)H(5))] (12) was synthesized by the photochemical reaction of Fe(dmpe)(2)(C[triple bond]CPh)(C[triple bond]C(CH(2))(4)C[triple bond]CH) (6e) with Fe(dmpe)(2)(CH(3))(2). Extended irradiation of the bisacetylide complexes with phenylacetylene resulted in insertion of the terminal alkyne into one of the metal acetylide bonds to give acetylide butenyne complexes. The structure of the acetylide butenyne complex, trans-[Fe(dmpe)(2)(C[triple bond]CC(6)H(4)OCH(3))(eta(1)-C(C(6)H(5))=CH(C[triple bond]CC(6)H(4)OCH(3)))] (9a) was determined by single-crystal X-ray diffraction.     

Syntheses of functionalized ferratricarbadecaboranyl complexes

The reactions of nitriles (RCN) with arachno-4,6-C(2)B(7)H(12)(-) provide a general route to functionalized tricarbadecaboranyl anions, 6-R-nido-5,6,9-C(3)B(7)H(9)(-), R = C(6)H(5) (2(-)), NC(CH(2))(4) (4(-)), (p-BrC(6)H(4))(Me(3)SiO)CH (6(-)), C(14)H(11) (8(-)), and H(3)BNMe(2)(CH(2))(2) (10(-)). Further reaction of these anions with (eta(5)-C(5)H(5))Fe(CO)(2)I yields the functionalized ferratricarbadecaboranyl complexes 1-(eta(5)-C(5)H(5))-2-C(6)H(5)-closo-1,2,3,4-FeC(3)B(7)H(9) (3), 1-(eta(5)-C(5)H(5))-2-NC(CH(2))(4)-closo-1,2,3,4-FeC(3)B(7)H(9) (5), 1-(eta(5)-C(5)H(5))-2-[(p-BrC(6)H(4))(Me(3)SiO)CH]-closo-1,2,3,4-FeC(3)B(7)H(9) (7), 1-(eta(5)-C(5)H(5))-2-C(14)H(11)-closo-1,2,3,4-FeC(3)B(7)H(9) (9), and 1-(eta(5)-C(5)H(5))-2-H(3)BNMe(2)(CH(2))(2)-closo-1,2,3,4-FeC(3)B(7)H(9) (11). Reaction of 11 with DABCO (triethylenediamine) resulted in removal of the BH(3) group coordinated to the nitrogen of the side chain, giving 1-(eta(5)-C(5)H(5))-2-NMe(2)(CH(2))(2)-closo-1,2,3,4-FeC(3)B(7)H(9) (12). Crystallographic studies of complexes 3, 5, 7, 9, and 11 confirmed that these complexes are ferrocene analogues in which a formal Fe(2+) ion is sandwiched between the cyclopentadienyl and tricarbadecaboranyl monoanionic ligands. The metals are eta(6)-coordinated to the puckered six-membered face of the tricarbadecaboranyl cage, with the exopolyhedral substituents bonded to the low-coordinate carbon adjacent to the iron.     

Formation,structure and reactivity of boryloxycarbyne complexes of group 6 metals

Reaction of the diborane(4) B(2)(NMe(2))(2)I(2) with two equivalents of K[(eta(5)-C(5)H(5))M(CO)(3)] (M=Cr, Mo, W) yielded the dinuclear boryloxycarbyne complexes [[(eta(5)-C(5)H(5))(OC)(2)M(triple bond)CO](2)B(2)(NMe(2))(2)] (4 a, M=Mo; b, M=W; c, M=Cr), which were fully characterised in solution by multinuclear NMR methods. The Mo and W complexes 4 a, b proved to be kinetically favoured products of this reaction and underwent quantitative rearrangement in solution to afford the complexes [[(eta(5)-C(5)H(5))(OC)(2)M(triple bond)CO]B(NMe(2))B(NMe(2))[M(CO)(3)(eta(5)-C(5)H(5))]] (5 a, M=Mo; b, M=W); 5 a was characterised by X-ray crystallography in the solid state. Corresponding reactions of B(2)(NMe(2))(2)I(2) with only one equivalent of K[(eta(5)-C(5)H(5))M(CO)(3)] (M=Mo, W) initially afforded 1:1 mixtures of the boryloxycarbyne complexes 4 a, b and unconsumed B(2)(NMe(2))(2)I(2). This mixture, however, yielded finally the diborane(4)yl complexes [(eta(5)-C(5)H(5))(OC)(3)M[B(NMe(2))B(NMe(2))I]] (6 a, M=Mo; b, M=W) by [(eta(5)-C(5)H(5))(OC)(3)M] transfer and rearrangement. Density functional calculations were carried out for 4 c and 5 a, b.     

Arene-ruthenium complexes of an acyclic thiolate-thioether and tridentate thioether derivatives resulting from ring-closure reactions

The reaction of [(eta(6)-arene)RuCl(2)](2) (arene = C(6)Me(6), 1,4-MeC(6)H(4)CHMe(2)) with a large excess of the dianion of bis(2-mercaptoethyl) sulfide, (HSCH(2)CH(2))(2)S, obtained from deprotonation of the dithiol with freshly prepared NaOMe, gives the deep red, monomeric complexes [(eta(6)-arene)Ru(eta(3)-C(4)H(8)S(3))] (arene = C(6)Me(6) (5), 1,4-MeC(6)H(4)CHMe(2) (6)) in which the dianion is bound to the metal atom through one thioether and two thiolate sulfur atoms. Complex 5 reacts with [(eta(6)-C(6)Me(6))RuCl(2)](2) (4) in a 2:1 mole ratio to give a quantitative yield of the chloride salt of a binuclear cation [((eta(6)-C(6)Me(6))Ru)(2)Cl(mu(2)-eta(2):eta(3)-C(4)H(8)S(3))](+) (7) in which the thiolate sulfur atoms of the [(eta(6)-C(6)Me(6))Ru(eta(3)-C(4)H(8)S(3))] group bridge to a (eta(6)-C(6)Me(6))RuCl unit. This compound is also obtained directly from the reaction of 4 with the dithiolate, if the Ru dimer is used in large excess. The binuclear complex [((eta(6)-C(6)Me(6))Ru)(2)(MeCN)(mu(2)-eta(2):eta(3)-C(4)H(8)S(3))](PF(6))(2).MeCN, (9)(PF(6))(2).MeCN, is obtained by treatment of (7)Cl with NH(4)PF(6) in acetonitrile. Protonation of 5 with HCl gave the mono- and diprotonated derivatives viz. [(eta(6)-C(6)Me(6))Ru(eta(3)-C(4)H(9)S(3))]Cl, (8)Cl, and [(eta(6)-C(6)Me(6))Ru(eta(3)-C(4)H(10)S(3))]Cl(2), (10)Cl(2), respectively. The reaction of 5 with methyl iodide gives both the mono- and di-S-methylated derivatives. Treatment of 5 with dibromoalkanes, Br(CH(2))(n)Br (n = 1-5), effects ring closure to give the (eta(6)-C(6)Me(6))Ru dications containing the trithia mesocyclic zS3 (z = 8-12) ligands, isolated as their PF(6) salts. The X-ray crystal structures of 5, 6, the solvates of (7)Cl and (9)(PF(6))(2), and the trithia mesocyclic Ru complexes (eta(6)-C(6)Me(6))Ru(zS3)(PF(6))(2) (z = 8-11) are reported.     

Synthesis,molecular structure,and C-C coupling reactions of carbeneruthenium(II) complexes with C5H5Ru(=CRR') and C5Me5Ru(=CRR') as molecular units

The ethene derivatives [(eta(5)-C(5)R(5))RuX(C(2)H(4))(PPh(3))] with R=H and Me, which have been prepared from the eta(3)-allylic compounds [(eta(5)-C(5)R(5))Ru(eta(3)-2-MeC(3)H(4))(PPh(3))] (1, 2) and acids HX under an ethene atmosphere, are excellent starting materials for the synthesis of a series of new halfsandwich-type ruthenium(II) complexes. The olefinic ligand is replaced not only by CO and pyridine, but also by internal and terminal alkynes to give (for X=Cl) alkyne, vinylidene, and allene compounds of the general composition [(eta(5)-C(5)R(5))RuCl(L)(PPh(3))] with L=C(2)(CO(2)Me)(2), Me(3)SiC(2)CO(2)Et, C=CHCO(2)R, and C(3)H(4). The allenylidene complex [(eta(5)-C(5)H(5))RuCl(=C=C=CPh(2))(PPh(3))] is directly accessible from 1 (R=H) in two steps with the propargylic alcohol HC triple bond CC(OH)Ph(2) as the precursor. The reactions of the ethene derivatives [(eta(5)-C(5)H(5))RuX(C(2)H(4))(PPh(3))] (X=Cl, CF(3)CO(2)) with diazo compounds RR'CN(2) yield the corresponding carbene complexes [(eta(5)-C(5)R(5))RuX(=CRR')(PPh(3))], while with ethyl diazoacetate (for X=Cl) the diethyl maleate compound [(eta(5)-C(5)H(5))RuCl[eta(2)-Z-C(2)H(2)(CO(2)Et)(2)](PPh(3))] is obtained. Halfsandwich-type ruthenium(II) complexes [(eta(5)-C(5)R(5))RuCl(=CHR')(PPh(3))] with secondary carbenes as ligands, as well as cationic species [(eta(5)-C(5)H(5))Ru(=CPh(2))(L)(PPh(3))]X with L=CO and CNtBu and X=AlCl(4) and PF(6), have also been prepared. The neutral compounds [(eta(5)-C(5)H(5))RuCl(=CRR')(PPh(3))] react with phenyllithium, methyllithium, and the vinyl Grignard reagent CH(2)=CHMgBr by displacement of the chloride and subsequent C-C coupling to generate halfsandwich-type ruthenium(II) complexes with eta(3)-benzyl, eta(3)-allyl, and substituted olefins as ligands. Protolytic cleavage of the metal-allylic bond in [(eta(5)-C(5)H(5))Ru(eta(3)-CH(2)CHCR(2))(PPh(3))] with acetic acid affords the corresponding olefins R(2)C=CHCH(3). The by-product of this process is the acetato derivative [(eta(5)-C(5)H(5))Ru(kappa(2)-O(2)CCH(3))(PPh(3))], which can be reconverted to the carbene complexes [(eta(5)-C(5)H(5))RuCl(=CR(2))(PPh(3))] in a one-pot reaction with R(2)CN(2) and Et(3)NHCl.     

Cube-type nitrido complexes containing titanium and alkali/alkaline-earth metals

Treatment of [[Ti(eta(5)-C(5)Me(5))(mu-NH)](3)(mu(3)-N)] with alkali-metal bis(trimethylsilyl)amido derivatives [M[N(SiMe(3))(2)]] in toluene affords edge-linked double-cube nitrido complexes [M(mu(4)-N)(mu(3)-NH)(2)[Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)]](2) (M = Li, Na, K, Rb, Cs) or corner-shared double-cube nitrido complexes [M(mu(3)-N)(mu(3)-NH)(5)[Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)](2)] (M = Na, K, Rb, Cs). Analogous reactions with 1/2 equiv of alkaline-earth bis(trimethylsilyl)amido derivatives [M[N(SiMe(3))(2)](2)(thf)(2)] give corner-shared double-cube nitrido complexes [M[(mu(3)-N)(mu(3)-NH)(2)Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)](2)] (M = Mg, Ca, Sr, Ba). If 1 equiv of the group 2 amido reagent is employed, single-cube-type derivatives [(thf)(x)[(Me(3)Si)(2)N]M[(mu(3)-N)(mu(3)-NH)(2)Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)]] (M = Mg, x = 0; M = Ca, Sr, Ba, x = 1) can be isolated or identified. The tetrahydrofuran molecules are easily displaced with 4-tert-butylpyridine in toluene, affording the analogous complexes [(tBupy)[(Me(3)Si)(2)N]M[(mu(3)-N)(mu(3)-NH)(2)Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)]] (M = Ca, Sr). The X-ray crystal structures of [M(mu(3)-N)(mu(3)-NH)(5)[Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)](2)] (M = K, Rb, Cs) and [M[(mu(3)-N)(mu(3)-NH)(2)Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3))-N)](2)] (M = Ca, Sr) have been determined. The properties and solid-state structures of the azaheterometallocubane complexes bearing alkali and alkaline-earth metals are discussed.     

Reaction of (mu-oxo)diiron(III) core with CO2 in N-methylimidazole: formation of mono(mu-carboxylato)(mu-oxo)diiron(III) complexes with N-methylimidazole as ligands

Several iron(III) complexes with N-methylimidazole (N-MeIm) as the ligand have been synthesized by using N-MeIm as the solvent. Under anaerobic conditions, [Fe(N-MeIm)(6)](ClO(4))(3) (1) reacts with stoichiometric amounts of water in N-MeIm to afford the (mu-oxo)diiron(III) complex, [Fe(2)(mu-O)(N-MeIm)(10)](ClO(4))(4) (3). Exposure of a solution of 3 in N-MeIm to stoichiometric and excess CO(2) gives rise to the (mu-oxo)(mu-carboxylato)diiron(III) species [Fe(2)(mu-O)(mu-HCO(2))(N-MeIm)(8)](ClO(4))(3) (4) and the methyl carbonate complex [Fe(2)(mu-O)(mu-CH(3)OCO(2))(N-MeIm)(8)](ClO(4))(3) (5), respectively. Formation of the formato-bridged complex 4 upon fixation of CO(2) by 3 in N-MeIm is unprecedentated. Methyl transfer from N-MeIm to a bicarbonato-bridged (mu-oxo)diiron(III) intermediate appears to give rise to 5. Complex 3 is a good starting material for the synthesis of (mu-oxo)mono(mu-carboxylato)diiron(III) species [Fe(2)(mu-O)(mu-RCO(2))(N-MeIm)(8)](ClO(4))(3) (where R = H (4), CH(3) (6), or C(6)H(5) (7)); addition of the respective carboxylate ligand in stoichiometric amount to a solution of 3 in N-MeIm affords these complexes in high yields. Attempts to add a third bridge to complexes 4, 6, and 7 to form the (mu-oxo)bis(mu-carboxylato)diiron(III) species result in the isolation of the previously known triiron(III) mu-eta(3)-oxo clusters [[Fe(mu-RCO(2))(2)(N-MeIm)](3)O](ClO(4)) (8). The structures of 3, 4, 6, and 7 allow one, for the first time, to inspect the various features of the [Fe(2)(mu-O)(mu-RCO(2))](3+) moiety with no strain from the ligand framework.     

Molecular nitrides containing group 4 and 5 metals: single and double azatitanocubanes

Treatment of [[Ti(eta(5)-C(5)Me(5))(micro-NH)](3)(micro(3)-N)] (1) with the imido complexes [Ti(NAr)Cl(2)(py)(3)] (Ar=2,4,6-C(6)H(2)Me(3)) and [Ti(NtBu)Cl(2)(py)(3)] in toluene affords the single azatitanocubanes [[Cl(2)(ArN)Ti]( micro(3)-NH)(3)[Ti(3)(eta(5)-C(5)Me(5))(3)(micro(3)-N)]].(C(7)H(8)) (2.C(7)H(8)) and [[Cl(2)Ti](micro(3)-N)(2)(micro(3)-NH)[Ti(3)(eta(5)-C(5)Me(5))(3)(micro(3)-N)]] (3), respectively. Similar reactions of complex 1 with the niobium and tantalum imido derivatives [[M(NtBu)(NHtBu)Cl(2)(NH(2)tBu)](2)] (M=Nb, Ta) in toluene give the single azaheterometallocubanes [[Cl(2)(tBuN)M](micro(3)-N)(micro(3)-NH)(2)[Ti(3)(eta(5)-C(5)Me(5))(3)(micro(3)-N)]] (M=Nb (4), Ta (5)), both complexes react with 2,4,6-trimethylaniline to yield the analogous species [[Cl(2)(ArN)M](micro(3)-N)(micro(3)-NH)(2)[Ti(3)(eta(5)-C(5)Me(5))(3)(micro(3)-N)]].(C(7)H(8)) (Ar=2,4,6-C(6)H(2)Me(3), M=Nb (6.C(7)H(8)), Ta (7.C(7)H(8))). Also the azaheterodicubanes [M[micro(3)-N)(2)(micro(3)-NH)](2)[Ti(3)(eta(5)-C(5)Me(5))(3)(micro(3)-N)](2)].2C(7)H(8) [M=Ti (8.2C(7)H(8)), Zr (9.2C(7)H(8))], and [M[(micro(3)-N)(5)(micro(3)-NH)][Ti(3)(eta(5)-C(5)Me(5))(3)(micro(3)-N)](2)].2 C(7)H(8) (Nb (10.2C(7)H(8)), Ta (11.2C(7)H(8))) were prepared from 1 and the homoleptic dimethylamido complex [M(NMe(2))(x)] (x=4, M=Ti, Zr; x=5, M=Nb, Ta) in toluene at 150 degrees C. X-ray crystal structure determinations were performed for 6 and 10, which revealed a cube- and double-cube-type core, respectively. For complexes 2 and 4-7 we observed and studied by DNMR a rotation or trigonal-twist of the organometallic ligands [[Ti(eta(5)-C(5)Me(5))(micro-NH)](3)(micro(3)-N)] (1) and [(micro(3)-N)(micro(3)-NH)(2)[Ti(3)(eta(5)-C(5)Me(5))(3)(micro(3)-N)]](1-). Density functional theory calculations were carried out on model complexes of 2, 3, and 8 to establish and understand their structures.     

Synthesis and characterization of half-sandwich N-heterocyclic carbene complexes of cobalt and rhodium

A series of novel half-sandwich M(I) and M(III) complexes (M = Co, Rh) bearing the N-heterocyclic carbene ligand 1,3-dimesitylimidazol-2-ylidene (IMes) have been prepared and characterized. Thus, (eta5-C(5)R(5))M(IMes)(C(2)H(4))(M = Co, Rh; R = H, Me) were obtained from the corresponding bis(ethene) complexes (eta5-C(5)R(5))M(C(2)H(4))(2), except for CpRh(IMes)(C(2)H(4)) which was prepared via the novel 16-electron Rh(I) compound Rh(IMes)(C(2)H(4))(2)Cl. The carbonyl compounds (eta5-C(5)R(5))Co(IMes)(CO)(R = H, Me) were synthesized by thermal CO substitution of (eta5-C(5)R(5))Co(CO)(2). A diamagnetic, apparently 16-electron Co(III) compound [CpCo(IMes)I](+)[I(3)(-)] was obtained from CpCo(IMes)(CO) and I(2). Finally, Co(III) and Rh(III) complexes CpCo(IMes)Me(2) and Cp*Rh(IMes)Me(2) were prepared by methylation of [CpCo(IMes)I](+)[I(3)(-)], and ligand exchange at Cp*Rh(Me(2)SO)Me(2), respectively. The molecular structures of CpCo(IMes)(CO), CpRh(IMes)(C(2)H(4)), Cp*Rh(IMes)(C(2)H(4)), and Cp*Rh(IMes)Me(2) were determined by single crystal X-ray diffraction. Steric and electronic factors imposed by the strongly donating and sterically demanding IMes ligand are discussed on the basis of X-ray crystallographic, NMR, and IR spectroscopic analyses. Very poor correlations are found between values for (1)J(Rh-C(carbene)) and dRh-C(carbene) data for Rh(i) N,N-heterocyclic carbene complexes including literature data and this work.     

Unusual coordination assemblies from platinum(II) thienyl and bithienyl complexes

Dinuclear Pt(2)Br(2)(dppf)(2)(mu-C(8)H(4)S(2)) exchanges with isonicotinic acid to release free bithiophene and gives a molecular square [Pt(4)(dppf)(4)(mu(2)-O(2)CC(5)H(4)N)(4)](4+)4OTf(-) which is an "all-ring" system with four Pt rings disposed at the corners of a larger macrocyclic ring. The related mononuclear complex PtBr(eta(1)(C2)-C(4)H(3)S)(dppf) reacts with AgOTf (OTf = triflate) to give [Pt(2)(dppf)(2)(mu(2),eta(1)(C),eta(1)(S)-C(4)H(3)S)(2)](2+)2OTf(-) with an unusual six-membered ring formed by the fusion of two Pt-thienyl entities at the sulfur sites. All the complexes are structurally characterized by single-crystal X-ray crystallography.     

A Search for pi/sigma Equilibria in Chiral Rhenium Imine Complexes of the Formula [(eta(5)-C(5)H(5))Re(NO)(PPh(3))(N(H)=C(CF(3))X)](+)TfO(-): Investigation of Electronic Effects upon the Binding Mode

Reaction of the amido complex (eta(5)-C(5)H(5))Re(NO)(PPh(3))(&Numl;H(2)) (2) and hexafluoroacetone gives the methyleneamido complex (eta(5)-C(5)H(5))Re(NO)(PPh(3))(&Numl;=C(CF(3))(2)) (3, 58%). Addition of TfOH to 3 yields the sigma-imine complex [(eta(5)-C(5)H(5))Re(NO)(PPh(3))(eta(1)-N(H)=C(CF(3))(2))](+)TfO(-) (4, 96%). Similar reactions of 2 with trifluoroacetaldehyde and then TfOH give the sigma-imine complex [(eta(5)-C(5)H(5))Re(NO)(PPh(3))(eta(1)-N(H)=C(CF(3))H)](+)TfO(-) (5, 78%) and sometimes small amounts of the corresponding pi-trifluoroacetaldehyde complex. Reaction of 5 and t-BuO(-)K(+) gives the methyleneamido complex (eta(5)-C(5)H(5))Re(NO)(PPh(3))(&Numl;=C(CF(3))H) (6, 82%). The IR and NMR properties of 3-6 are studied in detail. The (13)C NMR spectra show C=N signals (157-142 ppm) diagnostic of sigma-binding modes. No evidence is observed for pi isomers of 4 or 5. Analogous O=C(CF(3))X complexes give exclusively pi isomers, and rationales are discussed. Reactions of 3or 6 with MeOTf and heteroatom electrophiles are also described.     

Reactivity of the bis(pentafluorophenyl)boranes ClB(C6F5)2 and [HB(C6F5)2]n towards late transition metal reagents

The reactivities of the highly electrophilic boranes ClB(C(6)F(5))(2) (1) and [HB(C(6)F(5))(2)](n) (2) towards a range of organometallic reagents featuring metals from Groups 7-10 have been investigated. Salt elimination chemistry is observed 1 between and the nucleophilic anions eta(5)-C(5)R(5))Fe(CO)(2)](-)(R = H or Me) and [Mn(CO)(5)](-), leading to the generation of the novel boryl complexes (eta(5)-C(5)R(5))Fe(CO)(2)B(C(6)F(5))(2)[R = H (3) or Me (4)] and (OC)(5)MnB(C(6)F(5))(2) (5). Such systems are designed to probe the extent to which the strongly sigma-donor boryl ligand can also act as a pi-acceptor; a variety of spectroscopic, structural and computational probes imply that even with such strongly electron withdrawing boryl substituents, the pi component of the metal-boron linkage is a relatively minor one. Similar reactivity is observed towards the hydridomanganese anion [(eta(5)-C(5)H(4)Me)Mn(CO)(2)H](-), generating a thermally labile product identified spectroscopically as (eta(5)-C(5)H(4)Me)Mn(CO)(2)(H)B(C(6)F(5))(2) (6). Boranes 1 and 2 display different patterns of reactivity towards low-valent platinum and rhodium complexes than those demonstrated previously for less electrophilic reagents. Thus, reaction of 1 with (Ph(3)P)(2)Pt(H(2)C=CH(2)) ultimately generates EtB(C(6)F(5))(2) (10) as the major boron-containing product, together with cis-(Ph(3)P)(2)PtCl(2) and trans-(Ph(3)P)(2)Pt(C(6)F(5))Cl (9). The cationic platinum hydride [(Ph(3)P)(3)PtH](+) is identified as an intermediate in the reaction pathway. Reaction of with [(Ph(3)P)(2)Rh(mu-Cl)](2), in toluene on the other hand, appears to proceed via ligand abstraction with both Ph(3)P.HB(C(6)F(5))(2) (11) and the arene rhodium(I) cation [(Ph(3)P)(2)Rh(eta(6)-C(6)H(5)Me)](+) (14) ultimately being formed.     

Effect of trimethylsilyl substitution on the chemical properties of triarylphosphines and their corresponding metal-complexes: solubilising effect in supercritical carbon dioxide

The donor strengths of the following triarylphosphine ligands P(Ar)(2)(Ar')(Ar = Ar'= 4-Me(3)SiC(6)H(4), 1b; 4-Me(3)CC(6)H(4), 1d; 4-F(3)CC(6)H(4), 1e; Ar = C(6)H(5), Ar'= 4-Me(3)SiC(6)H(4), 1c) have been evaluated experimentally and theoretically. The measurements of the J(P-Se) coupling constants of the corresponding synthesised selenides Se=P(Ar)(2)(Ar'), 2b,c and the DFT calculation of the energies of the phosphine lone-pair (HOMO) reveal insignificant influence on the electronic properties of the substituted phosphines when the trimethylsilyl group is attached to the aryl ring, in marked contrast to the strong electronic effect of the trifluoromethyl group. These triarylphosphine ligands P(Ar)(2)(Ar') reacted with (eta5-C(5)H(5))Co(CO)(2), (eta5-C(5)H(5))Co(CO)I(2) or PdCl(2) to yield the new compounds (eta5-C(5)H(5))Co(CO)[P(Ar)(2)(Ar')], 3b,d; (eta5-C(5)H(5))CoI(2)[P(Ar)(2)(Ar')], 4b-e; and PdCl(2)[P(Ar)(2)(Ar')](2), 5b,c respectively. These complexes have been characterized and their spectroscopic properties compared with those reported for the known triphenylphosphine complexes. Again, the contrast of the (31)P NMR and (13)C NMR chemical shifts or C-O or M-Cl stretching frequencies, when applied, does not show an important electronic effect on the metal complex of the trimethylsilyl substituted phosphines with respect to P(C(6)H(5))(3) derivatives. Solubility measurements of complexes 3a and 3b in scCO(2) were performed. We conclude that Me(3)Si groups on the triarylphosphine improve the solubility of the corresponding metal complex in scCO(2).     

Reactions of Elemental Indium and Indium(I) Bromide with Nickel-Bromine Bonds: Structure of (eta(5)-C(5)H(5))(Ph(3)P)Ni-InBr(2)(O=PPh(3))

The reactions of elemental indium and In(I)Br with the carbonyl-free organonickel complexes (eta(5)-C(5)H(5))(PR(3))Ni-Br (R = CH(3), C(6)H(5)) have been studied in some detail. Either redox reactions to yield the ionic products [(eta(5)-C(5)H(5))(PR(3))(2)Ni][InBr(4)] (2a,b) occurred or the Ni-In bound systems (eta(5)-C(5)H(5))(PPh(3))Ni-InBr(2)(OPPh(3)) (3a) and [(eta(5)-C(5)H(5))(PPh(3))Ni](2)InBr (4) were obtained in good yields. The new compounds were characterized by elemental analysis, NMR, and mass spectrometry. A short Ni-In bond of 244.65(9) pm was found for 3a. Single crystal data for (eta(5)-C(5)H(5))(PPh(3))Ni-InBr(2)(OPPh(3)).THF (3a): triclinic, P1 with a = 1124.9(3), b = 1353.2(4), c = 1476.4(4) pm, alpha = 94.74(2) degrees, beta = 101.78(2) degrees, gamma = 109.64(1) degrees, V = 2044(1) x 10(6) pm(3), Z = 2, R = 0.053 (R(w) = 0.063).     

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.