Mixed nitrosyl/phosphinidene and nitrene/phosphinidene clusters of ruthenium

Reaction of the aminophosphinidene complex [Ru5(CO)15(mu 4-PNPri2)] 1 with [PPN][NO2] (PPN = Ph3P=N=PPh3) led to the mixed nitrosyl/phosphinidene cluster complex [PPN][Ru5(CO)13(mu-NO)(mu 4-PNPri2)] 2 which is transformed into the novel nitrene/phosphinidene cluster [Ru5(CO)10(mu-CO)2(mu 3-CO)(mu 4-NH)(mu 3-PNPri2)] 3 via treatment with triflic acid.     

Metal-templated diyne cyclodimerization and cyclotrimerization

Reaction of [Pt(CH3)2(COD)] (COD = 1,5-cyclooctadiene) with Ph2PCCCCPPh2 led to a mixture of [{Pt(CH3)2}2(mu-Ph2PC4PPh2)2] (1) and [{Pt(CH3)2}3(mu-Ph2PC4PPh2)3] (2). Reaction of [PtCl2(COD)] with Ph2PCCCCPPh2 led to a mixture of the thermally unstable compounds [{PtCl2}2(mu-Ph2PC4PPh2)2] (3) and [{PtCl2}3(mu-Ph2PC4PPh2)3] (4) which transform into [{PtMe2}2{mu-C8(PPh2)4}] (5) and [{PtMe2}3{mu3-C12(PPh2)6}] (6) containing 8-membered diene-diyne and 12-membered triene-triyne rings, respectively. Compound 2 can be converted to [{PtMe2}3{C12(PPh2)6}] (7) by heating with CuCl at 80 degrees C, while 1 can be heated without significant cycloaddition.     

Transformation of mu4-phosphinidenes at an Ru5 center: isolation and structural characterization of hydroxyphosphinidene cluster acids, fluorophosphinidenes, and a novel mu5-phosphide

Acid hydrolysis of [Ru(5)(CO)(15)(mu(4)-PN(i)Pr(2))] (2) or protonation of the anionic PO cluster [Ru(5)(CO)(15)(mu(4)-PO)](-) (3) affords the hydroxyphosphinidene complex [Ru(5)(CO)(15)(mu(4)-POH)].1.[H(2)N(i)()Pr(2)][CF(3)SO(3)], which cocrystallizes with a hydrogen-bonded ammonium triflate salt. Reaction of [Ru(5)(CO)(15)(mu(4)-PN(i)Pr(2))] (2) with bis(diphenylphosphino)methane (dppm) leads to [Ru(5)(CO)(13)(mu-dppm)(mu(4)-PN(i)Pr(2))] (4). Acid hydrolysis of 4 leads to the dppm-substituted hydroxyphosphinidene [Ru(5)(CO)(13)(mu-dppm)(mu(4)-POH)] (5), which is analogous to 1, but unlike 1, can be readily isolated as the free hydroxyphosphinidene acid. Compound 5 can also be formed by reaction of 3 with dppm and acid. The cationic hydride cluster [Ru(5)(CO)(13)(mu-dppm)(mu(3)-H)(mu(4)-POH)][CF(3)SO(3)] (6) can be isolated from the same reaction if chromatography is not used. Compound 4 also reacts with HBF(4) to form the fluorophosphinidene cluster [Ru(5)(CO)(13)(mu-dppm)(mu(4)-PF)] (7), while reaction with HCl leads to the mu-chloro, mu(5)-phosphide cluster [Ru(5)(CO)(13)(mu-dppm)(mu-Cl)(mu(5)-P)] (8).     

Selective coupling of methylene groups at a Rh/Os core, yielding C2, C3, or C4 fragments: roles of the adjacent metals in carbon-carbon bond formation

The mixed-metal complex, [RhOs(CO)(4)(dppm)(2)][BF(4)] (1; dppm = micro-Ph(2)PCH(2)PPh(2)) reacts with diazomethane to yield a number of products resulting from methylene incorporation into the bimetallic core. At -80 degrees C the reaction between 1 and CH(2)N(2) yields the methylene-bridged [RhOs(CO)(3)(micro-CH(2))(micro-CO)(dppm)(2)][BF(4)] (2), which reacts further at ambient temperature to give the allyl methyl species, [RhOs(eta(1)-C(3)H(5))(CH(3))(CO)(3)(dppm)(2)][BF(4)] (4). At intermediate temperatures compounds 1 and 2 react with diazomethane to yield the butanediyl complex [RhOs(C(4)H(8))(CO)(3)(dppm)(2)][BF(4)] (3) by the incorporation and coupling of four methylene units. Compound 2 is proposed to be an intermediate in the formation of 3 and 4 from 1 and on the basis of labeling studies a mechanism has been proposed in which sequential insertions of diazomethane-generated methylene fragments into the Rh-C bond of bridging hydrocarbyl fragments occur. Reaction of the tricarbonyl species, [RhOs(CO)(3)(micro-CH(2))(dppm)(2)][BF(4)] with diazomethane over a range of temperatures generates the ethylene complex [RhOs(eta(2)-C(2)H(4))(CO)(3)(dppm)(2)][BF(4)] (7a), but no further incorporation of methylene groups is observed. This observation suggests that carbonyl loss in the formation of the above allyl and butanediyl species only occurs after incorporation of the third methylene fragment. Attempts to generate C(2)-bridged species by the reaction of 1 with ethylene gave no reaction, however, in the presence of trimethylamine oxide the ethylene adducts [RhOs(eta(2)-C(2)H(4))(CO)(3)(dppm)(2)][BF(4)] (7b; an isomer of 7a) and [RhOs(eta(2)-C(2)H(4))(2)(CO)(2)(dppm)(2)][BF(4)] (8) were obtained. The relationship of the above products to the selective coupling of methylene groups, and the roles of the different metals are discussed.     

The Synthesis and Reactivity of New μ 2- and μ 3-Aminophosphinidene Cobalt Complexes

The reaction of K[Co(CO)₄] and PCl₂(TMP) at –5°C leads to the unstable and reactive -phosphinidene complex [Co₂(CO)₆{-P(TMP)}] (1), while the same reaction carried out at 35°C gives the chlorophosphido and phosphinidene bridged cluster [Co₃(CO)₇{-P(Cl)TMP}{ ₃-P(TMP)}] (2) (TMP=2,2,6,6-tetramethylpiperidyl). Compound 1 reacts with dppm (dppm=bis(diphenyl- phosphino)methane) and [Co₂(CO)₈] to form the more stable substitution product [Co₂(CO)₄{-P(TMP)}(-dppm)] (3) and [Co₄(CO)₇(-CO)₃{ ₃-P(TMP)}] (4) respectively. The first example of a cationic ₃-phosphinidene cluster compound [Co₃(CO)₉{ ₃-P(TMP)}][AlCl₄] (5) is obtained from reaction of 3 with AlCl₃. The X-ray structures of clusters 2 and 5 are discussed.     

A thermally stable and sterically unprotected terminal electrophilic phosphinidene complex of cobalt and its conversion to an eta(1)-phosphirene

The terminal chloroaminophosphido complex [Co(CO)3(PPh3){P(Cl)NiPr2}] is formed via reaction of K[Co(CO)4] with iPr2NPCl2 in the presence of triphenylphosphine. Chloride abstraction by aluminum trichloride leads to the first terminal phosphinidene complex of cobalt, [Co(CO)3(PPh3)(PNiPr2)][AlCl4]. The electrophilicity of the phosphinidene was demonstrated by its reaction with diphenylacetylene to form the phosphirene complex [Co(CO)3(PPh3){P(NiPr2)C(Ph)C(Ph)}][AlCl4].     

Tetraplatinum Cluster Complexes

The tetranuclear platinum cluster complexes [Pt₄(-CO)₃(-dppm)₃(PPh₃)]²⁺ and [Pt₄(-H)(-CO)₂(-dppm)₃(PPh₃)]⁺ have been prepared by cluster expansion. They have butterfly structures and are fluxional.     

Supra-supra, supra-antara, and stepwise-diradical pathways for an observed 16-electron double-[4 + 4] cycloaddition within metal-templated dialkyne dimers (PtX2)2(μ-R2PCCCCPR2)2

Quantum chemistry calculations are used to provide insight into the cycloaddition of two dialkyne chains in initially monocyclic organoplatinum dimers of the type (PtX(2))(2)(μ-R(2)PC(4)PR(2))(2), where X = Cl or Me and R = Ph or Me. Previous experimental studies showed that the cycloaddition occurs with {X, R} = {Cl, Ph} but not {Me, Ph}. Two concerted pericyclic paths, a D(2h)-symmetry double-[π4s+π4s] "Hu?ckel path" and a D(2)-symmetry double-[π4s+π4a] "Mo?bius path", were explored via orbital energy correlation diagrams (OECDs) computed using a singly occupied molecular orbital technique developed earlier. In accord with pericyclic reaction theory, the 16e(-) rearrangement is forbidden along the D(2h) Hu?ckel path; four electrons would need to change their orbital symmetries. The D(2) Mo?bius path, afforded by the natural twist in the reactant structure which allows the desired Mo?bius orbital connectivity for a 4n rearrangement, is concluded to be a borderline forbidden pathway. This Mo?bius path creates avoided crossings in the OECD, which allows consistent orbital populations throughout the reaction, but it does not cause a change in intended orbital correlation, and the predicted activation barrier is rather high (～50 kcal mol(-1)). The avoided crossings show strong coupling, but a clear HOMO-LUMO gap for the reaction is not produced. A stepwise path is also presented, with evidence of its diradical character.