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Michael I. Bruce, Alexandre Burgun, Jonathan George, Brian K. Nicholson, Christian R. Parker, Brian W. Skelton, Nancy Scoleri, Christopher J. Sumby, Natasha N. Zaitseva

Several complexes containing Ru(dppe)Cp* fragments attached to heterocyclic ligands were obtained from polycyanocarbons. Reactions of Ru{C CC(CN) C(CN)2}(dppe)Cp* with LiC CSiMe3 and LiOCH CH2 gave binuclear {[Ru(dppe)Cp*]C C–c-C C(C CSiMe3)N(H⋯OH2)CC C(CN)}2(N N) 2 and Ru{c-C CHC[ C(CN)2]CH CHO}(dppe)Cp* 4 [together with known Ru{C CCMe C(CN)2}(dppe)Cp* 3], respectively, while lithiation of Ru(C CC CH)(dppe)Cp* and subsequent reaction with TCNE afforded Ru{C C–c-C C(CN)C(O)NH[ C(CN)2]}(dppe)Cp* 6 and Ru{C C–c-C CHC[ C(CN)2]NHCMe N}(dppe)Cp* 7, as well as known {Ru(dppe)Cp*}2{μ-C CC[ C(CN)2]C[ C(CN)2]C C} 5. A second product from the earlier described reaction between TCNE and Ru(C CC CI)(dppe)Cp* was identified as Ru{C C–c-CC(CN)C(CN) C(NH2)C(CN)2}(dppe)Cp* 9. X-ray determined structures of 2, 4, 6, 7 and 9 are reported together with plausible routes by which they may be formed.

Treatment of Ru(C CPh)(PPh3)2Cp 1 with Ag[PF6] (2/1 molar ratio, in toluene) affords [Ag{η2-PhC2[Ru(PPh3)2Cp]}2]PF6 2, characterised by analysis, spectroscopy and a single-crystal X-ray structure determination. A similar reaction in CH2Cl2 (1/1 molar ratio) gives [{Cp(Ph3P)2Ru} C CHC6H4CPh C {Ru(PPh3)2Cp}](PF6)2 4 by oxidative coupling of two alkynyl-Ru radicals.

Desilylation of Fc’(C CSiMe3)2 [1; Fc’ = Fe(η-C5H4−)2] with LiMe or KOH/MeOH, followed by addition of AuCl(PR3), afforded Fc’{C CAu(PR3)}2 [R = Ph 2a, tol 2b]; the Ru analogue of 2a was also prepared. The XRD structures of 1 and 2a are reported. In the presence of CuI, a similar reaction over 2 h afforded the Au4 cluster Au4{(C C)2Fc’}2(PPh3)2 3. The X-ray determined structure of 3 showed a planar centrosymmetric Au4 rhomb, two opposed Au atoms being σ-bonded to the C C group, while the other two Au atoms are each η2-bonded to the C C group and a PPh3 ligand.

Reactions between [M 2 (dppm) 2 (NCMe) 2 ]X 2 [M = Ag, X = ClO 4 ; M = Cu, X = BF 4 ] and Ru(C CC CM)(dppe)Cp∗ [M = Ag, Cu; generated in situ from Ru(C CC CH)(dppe)Cp∗ and AgNO 3 or CuCl(PPh 3 ), respectively] afford the cationic mixed-metal cluster diynyl complexes [M 6 {μ 3 -C CC C[Ru(dppe)Cp∗]} 4 (μ-dppm) 2 ]X 2 , of which the structures were determined by single-crystal XRD studies. Electrochemical studies indicate that there is no interaction between the ruthenium centres. Reactions between [M 2 (μ-dppm) 2 (NCMe) 2 ](BF 4 ) 2 and Ru(C CC CM′)(dppe)Cp∗ (M,M′ = Cu, Ag) afforded a mixture of Ag 6− n Cu n clusters, as shown by ES-MS and crystallographic studies. Preliminary studies suggest that extensive disproportionation occurs in solution.

Several complexes containing Co3 carbonyl clusters end-capping carbon chains of various lengths are described. Pd(0)/Cu(I)-catalysed reactions between {Co3{μ3-C(C C)2Au(PPh3)}(μ-dppm)(CO)7 and I(C C)2SiMe3 or FcC CI gave {Co3{μ3-C(C C)xR}(μ-dppm)(CO)7 [x = 4, R = SiMe3 3; x = 3, R = Fc 8]; treatment of 3 with NaOMe and AuCl(PPh3) gave 4 [x = 4, R = Au(PPh3)]. Related preparations of Co3{μ3-C(C C)2[Ru(PP)Cp′]}(μ-dppm)n(CO)9−2n [PP = (PPh3)2, Cp’ = Cp, n = 1, 5; PP = dppe, Cp′ = Cp∗, n = 1, 6; 0, 7] are also described. Syntheses of bis-cluster complexes {Co3(μ-dppm)(CO)7}2(μ-Cx) (x = 14, 12; 16, 9; 18, 11; 26, 10) – the latter being the longest cluster-capped Cx chains so far described – and the mercury-bridged compounds Hg{(C C)xC[Co3(μ-dppm)(CO)7]}2 (x = 1, 13; 2, 14) are reported. The molecular structures of 7, 12, 13 and 14, as well as of Co3(μ3-CC CSiMe3)(μ-dppm)(CO)6(PPh3) (15) and Co3{μ3-CC(O)OEt}(μ-dppm)(CO)7 (16), are reported.

Addition of [I(py)2]BF4 to Ru(C CH)(dppe)Cp∗ gave the iodovinylidene [Ru( C CHI)(dppe)Cp∗]BF4 1, which could be deprotonated to Ru(C CI)(dppe)Cp∗ 2. The attempted preparation of Ru(C CC CI)(dppe)Cp∗, followed by derivatisation with tcne, gave the dienynyl Ru{C CC[ C(CN)2]CI C(CN)2}(dppe)Cp∗ 3. The Pd(0)/Cu(I)-catalysed reaction of 3 with Ru{C CC CAu(PPh3)}(dppe)Cp∗ afforded Ru{C CC C(CN)2C C(CN)2Au(PPh3)}(dppe)Cp∗ 4 by formal replacement of I+ by [Au(PPh3)]+. XRD structures of 1–4 are reported.

The reaction between RuCl(PPh 3 ) 2 Cp ∗ and {Cu(CCPh)} n in refluxing benzene afforded Ru 2 Cu 2 (C 2 Ph) 5 H 2 (Cl)(PPh 3 )Cp ∗ 2 , which contains an unusual tetramer of the phenylethynyl group which interacts with an Ru…Cu…Cu…Ru chain. The second Ru atom is part of a ruthenocenyl moiety which interacts weakly with the second Cu atom, and bears a vinylidene which bridges an Ru–Cu vector. The structure of a second modification of Ru(C CPh)(CO)(PPh 3 )Cp ∗ is also reported.

A series of alkynyl-tricobalt carbonyl clusters, Co3(μ3-CnR)(μ-dppm)(CO)7 [R = But, Ph, C6H4I, C6H4C CPh, SiMe3, Fc, Au(PPh3)] containing three, five or seven carbons in the chain, have been prepared by elimination of phosphine–gold(I) halides in reactions between Co3(μ3-CBr)(μ-dppm)(CO)7 and Au(C CR)(PPh3) or between Co3{μ3-CC CAu(PR3)} (μ-dppm)(CO)7 (R = Ph, tol) and IC CR′ (R′ = SiMe3, Fc). The use of poly-substituted arenes or ferrocenes has enabled preparation of the complexes 1,4-{(OC)7(μ-dppm)Co3 (μ3-CC C)}2C6H3X-5 (X = H, Br), 1,3,5-{(OC)7(μ-dppm)Co3(μ3-CC C)}3C6H3 and 1,1′-{(OC)7(μ-dppm)Co3 (μ3-CC C)}2Fc′ [Fc′ = Fe(η-C5H4-)2]. The X-ray determined molecular structures of 12 of the complexes are reported.

Reactions of {(Ph 3 P)AuC C} 2 C C{C CAu(PPh 3 )} 2 ( 1b ), with Co 3 (μ-CBr)(μ-dppm) n (CO) 9−2 n ( n = 0, 1) result in complete or partial elimination of AuBr(PPh 3 ) to give the complexes {(OC) 9 Co 3 -μ 3 -CC C} 2 C C{C C-μ 3 -CCo 3 (CO) 9 } 2 ( 3 ), trans -{(OC) 7 (μ-dppm)Co 3 -μ 3 -CC C}(HC C)C C{C CAu(PPh 3 )}{C C-μ 3 -CCo 3 (μ-dppm)(CO) 7 } ( 4 ), {(OC) 7 (μ-dppm)Co 3 -μ 3 -CC C} 2 C C(C CH){C C-μ 3 -CCo 3 (μ-dppm)(CO) 7 } ( 5 ) and {(OC) 7 (μ-dppm)Co 3 -μ 3 -CC C} 2 C C{C CAu(PPh 3 )}{C C-μ 3 -CCo 3 (μ-dppm)(CO) 7 } ( 6 ), which have been identified by spectroscopic methods and in the cases of 3 , 4 and 5 , by single-crystal X-ray diffraction methods.

Reactions of platinum(II) chloro-phosphine complexes with Co3(μ3-CC CC CSiMe3)(μ-dppm)(CO)7 in the presence of NaOMe have given the compounds Pt{C CC C-μ3-C[Co3(μ-dppm)(CO)7]}2(dppe) (1), trans-Pt{C CC C-μ3-C[Co3(μ-dppm)(CO)7]}2(PEt3)2 (2) and trans-Pt{C CC C-μ3-C[Co3(μ-dppm) (CO)6(PPh3)]}2(PPh3)2 (3), each of which contains two Co3 clusters linked by C5 chains to the Pt centre. Electrochemical studies (CVs) show the presence of both oxidation and reduction processes, the latter probably occurring on the CCo3 cores. Ready reductive elimination of {Co3(μ-dppm)(CO)7}2(μ3:μ3-C10) occurs from 1 upon heating. The X-ray study of 3 was carried out using synchrotron radiation (Advanced Photon Source, Argonne, IL) to confirm its structure.

The syntheses of several diynylgold(I) phosphine complexes, including Au(C CC CH){P(tol)3} (1), Au(C CC CSiMe3)(PR3) (R = Ph 2-Ph, tol 2-tol), Au(C CC CFc)(PPh3) (3), {(tol)3P}Au(C C)nAu{P(tol)3} [n = 2 (4), 3 (6), 4 (7)], {(Ph3P)Au}C CC C{Au[P(tol)3]} (5), [ppn][Au{C CC CAu[P(tol)3]}2] (8), [Au2(μ-I)(μ-dppm)2][Au(C CC CSiMe3)2] (9), Hg{C CC CAu(PR3)}2 (R = Ph 10-Ph, tol 10-tol) and {(triphos)Cu}C CC C{Au[P(tol)3]} (11) are described. Of these, the X-ray molecular structures of 1, 2-tol, 3, 4 and 9 have been determined.

Complexes containing C4 ligands attached to one or two AuRu3 clusters by conventional σ, 2π interactions have been obtained from reactions between (R3P)AuC≡CC≡CAu(PR3) (R = Ph, tol) or Au(C≡CC≡CH){P(tol)3} and either Ru3(CO)12, Ru3(CO)10(NCMe)2 or Ru3(μ-dppm)(CO)10. The X-ray determined structures of {(R3P)AuRu3(CO)9}2(μ3,η2:μ3,η2-C2C2) [R = Ph (1) (three solvates), tol (2)], AuRu3{μ3,η2-C2C≡CAu(PPh3)}(CO)9(PPh3) (3) and {(Ph3P)AuRu3(μ-dppm)(CO)7} (μ3,η2:μ3,η2-C2C2){Ru3(μ-H)(μ-dppm)(CO)7} (4) are reported.

The Pd(0)/Cu(I)-catalysed reactions between Co 3 (μ 3 -CBr) (CO) 9 and W(C CC CH)(CO) 3 Cp gives the C 5 complex {Cp(OC) 3 W}C CC CC{Co 3 (CO) 9 } ( 2 ). Similarly, Co 3 (μ 3 -CBr)(μ-dppm)(CO) 7 and W(C CC CH)(CO) 3 Cp or Ru(C CC CH)(dppe)Cp* give {Cp(OC) 3 W}C CC CC{Co 3 (μ-dppm)(CO) 7 } and {Cp*(dppe)Ru}C CC CC{Co 3 (μ-dppmn)(CO) 7 } ( 5 ). An attempt to prepare a C 3 analogue from Ru(C CH)(PPh 3 ) 2 Cp and Co 3 (μ 3 -CBr)(CO) 9 gave instead the acyl derivative {Cp(Ph 3 P) 2 Ru}C CC(O)C{Co 3 (CO) 8 (PPh 3 )} ( 7 ). The X-ray structures of 2 , 5 and 7 are reported: the C 5 chains in 2 and 5 have an essentially unperturbed –C C–C C–C formulation.

The reaction between Ru 3 (μ-H){μ 3 -C 2 CPh 2 (OH)}(CO) 9 and HCCPh, carried out in the presence of HBF 4 · Me 2 O, afforded the cluster complexes Ru 3 (μ-H)(μ 3 -CPh 2 CCCCPh)(CO) 9 ( 5 ) and Ru 3 {μ 3 -CPhCHCC(CPh 2 )CHCPh}(μ-CO)(CO) 8 ( 6 ), both of which were characterised by single-crystal X-ray studies.

Complexes containing a Co3 cluster linked to SiMe3, Au(PPh3), W(CO)3Cp and Fc groups by a C5 chain have been prepared by elimination of AuBr(PR3) (R=Ph, tol) in the reactions between Co3(μ3-CBr)(μ-dppm)(CO)7 and {(R3P)Au}CCCCX [X=SiMe3, W(CO)3Cp] or {(OC)7(μ-dppm)Co3}CCC{Au(PPh3)} and FcCCI (X=Fc). Subsequent auro-desilylation of the SiMe3 compound affords {(OC)7(μ-dppm)Co3}CCCCC{Au[P(tol)3]}. Single-crystal X-ray structures of the W(CO)3Cp, Au{P(tol)3} and Fc complexes are reported. The C5 chain shows little departure from a formal CCCCC fragment.

Reactions of Co3(μ3-CBr)(μ-dppm)(CO)7 with {Au[P(tol)3]}2{μ-(CC)n} (n=2–4) have given {Co3(μ-dppm)(CO)7}{μ3:μ3-C(CC)nC} [n=2 (1), 3 (2), 4 (3)] containing carbon chains capped by the cobalt clusters. Tetracyanoethene reacts with 2 to give {Co3(μ-dppm)(CO)7}2{μ3:μ3-C(CC)2C[C(CN)2]C[C(CN)2]C} (4). X-ray structural characterisation of 1, 3 and 4 are reported, that for 3 being the first of a cluster-capped C10 chain.

Reactions of FcCCH (a), HCCCCFc (b) and FcCCCCFc (c) with Ru3(CO)10(NCMe)2 (all) and Ru3(μ-dppm)(CO)10 (b and c only) are described. Among the products, the complexes Ru3(μ3-RC2R′)(μ-CO)(CO)9 (R=H, R′=Fc 1, CCFc 2; R=R′=Fc 5), Ru3(μ-H)(μ3-C2CCFc)(μ-dppm)(CO)7 3, Ru3(μ3-FcC2CCFc)(μ-dppm)(μ-CO)(CO)7 6 and Ru3{μ3-C4Fc2(CCFc)2}(μ-dppm)(μ-CO)(CO)5 7 were characterised, including single-crystal structure determinations for 1, 3, 5 and 7; that of 7 did not differ significantly from an earlier study of a mixed CH2Cl2–C6H6 solvate.

The reaction of C2(CN)4 with Ru(CCPh)(dppm)Cp* in THF has given the anticipated tetracyanobuta-1,3-dien-2-yl complex Ru{C[C(CN)2]CPhC(CN)2}(dppm)Cp* (3). In benzene, η3-cyano-enyl complexes Ru{η3-C[C(CN)2]CPhCC(CN)2}(L)Cp* (L=dppm-P (4) or dppmO (5)) are formed, the latter by adventitious oxidation. On warming, complex 3 rearranges to the cyanoruthenium–ylid complex Ru(CN){C(CN)C[CPhC(CN)2]PPh2CH2PPh2}Cp* (6). A possible reaction sequence, involving a zwitterionic intermediate such as Ru(δ-)(CN){C(CN)C(δ+)CPhC(CN)2}(dppm-P)Cp* D, is discussed. Only the η1-dienyl complex 7 is obtained from Ru(CCPh)(dppe)Cp* and TCNE.

Reactions between Ru3(μ3-PhC2CCPh)(μ-dppm)(CO)8 (1) and SiMe3CCCCSiMe3 have given the complexes Ru2(μ-dppm){μ-C(CCPh)CPhC(SiMe3)C(CCSiMe3)}(CO)4 (3), containing the two diynes coupled in head-to-head fashion, Ru3{μ3C(SiMe3)C(CCSiMe3)C(CPh)C(CPh)C(O)}(μ-dppm)(CO)7 (4), containing a metalla–indenone ligand formed by coupling of the two diynes with CO, and Ru4(μ4-PhC2CCPh)(μ4-SiMe3C2CCSiMe3)(μ-dppm)(μ-CO)(CO)8 (6), in which the two diynes are on opposite sides of a puckered Ru4 rhomboid. Also formed were thermolysis products of 1, Ru3{μ3-CPhCHCC(C6H4)}(μ-dppm)(CO)8 (5) (previously described) and Ru4(μ4-PhC2CCPh)(μ-dppm)(CO)10 (7), the dppm-substitution product of Ru4(μ4-PhC2CCPh)(CO)12. The X-ray determined structures of 3, 6 and 7 are reported.

Reactions between Ru3(μ-dppm)(CO)10 and PhC≡CC≡CPh in thf, in the presence of Me3NO, afford the complexes Ru3(μ3-PhC2C≡CPh)(μ-dppm)(μ-CO)(CO)7 (1) and Ru3(μ-dppm)μ-C4Ph2(C≡CPh)2(CO)6 (2). Complex 1 was also obtained from Ru3(μ3-PhC2C≡CPh)(μ-CO)(CO)9 (3) and dppm in thf on heating. Two of the complexes formed by thermolysis of 1 in xylene at 130°C were identified crystallographically as Ru3μ3-CPhCHCC(C6H4-2)(μ-dppm)(CO)8 (4) and Ru3μ3-C4H2Ph2(μCO)(CO)5(dppm) (5). In 4, fragmentation of the cluster and metallation of one of the diyne phenyl groups took place; the dppm ligand bridges two non-bonded Ru atoms. In 5, partial hydrogenation of the diyne has occurred to give a 2η1:η4:η4-butadiendiyl ligand, the dppm ligand adopting a chelating mode on one of the two Ru atoms which is η4 attached to the hydrocarbon. In comparison, thermolysis of 3 gave Ru4(μ4-PhC2C≡CPh)(CO)n(n = 12 (6) and 14 (7)). The former has a distorted C2Ru4 octahedral core, while in the latter the Ru3 cluster has fragmented to give a ruthenacyclopentadiene derivative in which the central C-C bond bridges an Ru2(CO)8 group.

Reactions of RuCl(PPh3)2Cp∗ with 1-alkynes in non-polar solvents afford the neutral vinylidene complexes RuCl(CCHR)(PPh3) Cp∗ [RPh (X-ray structure), Bu1, SiMe3, CO2Me]; a novel 1,3 elimination of HCl induced by NaOMe in the presence of a variety of ligands gives the chiral-at-metal complexes Ru(CCR)(L)(PPh3)Cp∗ [LCO, C2H4 (X-ray structure), PR3, P(OR)3, O2, S2, CS2 (for example)].