A New Type of Tweezer Complex Involving a Rhenium−Rhenium Multiple Bond That Enforces an Unusual Structure in a Dipalladium(II) Unit

The substitution of the μ-acetato ligands in cis-Re2(μ-O2CCH3)2Cl2(μ-dppm)2 (1, dppm = Ph2PCH2PPh2) and trans-Re2(μ-O2CCH3)2Cl2(μ-dppE)2 (2, dppE = Ph2PC(CH2)PPh2) by [4-Ph2PC6H4CO2]- occurs with retention of stereochemistry to give cis-Re2(μ-O2CC6H4-4-PPh2)2Cl2(μ-dppm)2 (3) and trans-Re2(μ-O2CC6H4-4-PPh2)2Cl2(μ-dppE)2 (6), respectively. The uncoordinated phosphine groups in complexes 3 and 6 have been used to form mixed-metal assemblies with Au(I) and Pd(II), including the Re2Pd2 complex cis-Re2(μ-O2CC6H4-4-PPh2)2Cl2(μ-dppm)2(Pd2Cl4) (5), in which the planar [(P)ClPd(μ-Cl)2PdCl(P)] unit has the unusual cis structure. The crystal structures of 3 and 5 have been determined

Unsymmetrical Dirhenium Complexes That Contain [Re₂]⁶⁺ and [Re₂]⁵⁺ Cores Complexed by Tridentate Ligands with P₂O and P₂N Donor Sets

The quadruply bonded dirhenium(III) complex (n-Bu4N)2Re2Cl8 reacts with tridentate ligands that contain essentially planar P,O,P donor sets to afford the complexes Re2Cl6(η3-L1) (3) (L1 = bis[2-(diphenylphosphino)phenyl]ether) and (n-Bu4N)[Re2Cl7(η1-L2)] (4) (L2 = 4,6-bis(diphenylphosphino)dibenzofuran). Spectroscopic and electrochemical data support the unsymmetrical structure Cl4ReReCl2(η3-L1) in the case of 3, while 4 contains monodentate P-bound L2; both complexes contain ReRe bonds. The synthon cis-Re2(μ-O2CCH3)2Cl4(H2O)2 reacts with ligands L1, L2, 2,6-bis(diphenylphosphinomethyl)pyridine (L3), bis[2-(diphenylphosphino)ethyl]amine (L4), and N,N-bis[2-(diphenylphosphino)ethyl]trimethylacetamide (L5) to give the paramagnetic complexes Re2(μ-O2CCH3)Cl4(η3-Ln) (5−9) with Re bonds. The lability of the μ-acetato ligands in 5−9 has been demonstrated by the reactions of compounds 5 (n = 1) and 7 (n = 3) with 4-Ph2PC6H4CO2H, 2-Ph2PC6H4CO2H, and quinoline-4-carboxylic acid to give complexes 10−12 (from 5) and 13−15 (from 7), respectively. These products contain uncoordinated donor atoms that can be used to produce mixed-metal assemblies. Compounds 5 and 7 also react with terephthalic acid (1,4-C6H4(CO2H) to give [Re2Cl4(η3-L1)]2(μ-O2CC6H4CO2) (16) and [Re2Cl4(η3-L3)]2(μ-O2CC6H4CO2) (17) in which electronic coupling between the paramagnetic sets of dirhenium units is very weak. Single-crystal X-ray structure determinations have been carried out on complexes 5−8, 11, 12, and 14−16

Coupling of Edge-Sharing Bioctahedral Dirhenium(II) Units through the Agency of [N(CN)₂]^-, [C(CN)₃]^-, and [Ni(CN)₄]^2- Linkages

Coupling of Edge-Sharing Bioctahedral Dirhenium(II) Units through the Agency of [N(CN)2]-, [C(CN)3]-, and [Ni(CN)4]2- Linkage

Involvement of Multiply Bonded Dirhenium Complexes in Mixed-Metal Assemblies. Isolation and Characterization of a New Type of Re₄Pd₂ Cluster

Involvement of Multiply Bonded Dirhenium Complexes in Mixed-Metal Assemblies. Isolation and Characterization of a New Type of Re4Pd2 Cluste

Mixed-Metal Assemblies Containing Multiply Bonded Dirhenium Species Linked through Thiocyanate- and Cyanide-Containing Bridging Units

The lability of the terminal Re−Cl bond that is cis to the bridging CO ligand in the edge-sharing bioctahedral complexes Re2(μ-Cl)(μ-CO)(μ-PP)2Cl3(L), where PP = Ph2PC(CH2)PPh2 (dppE) when L = CO (1) and PP = Ph2PCH2PPh2 (dppm) when L = CO (2) or XyINC (3), has been exploited in the preparation of mixed-metal Re4Pd2, Re2Ag, Re2W, Re2Pt, and Re2Rh assemblies, in which the dirhenium units are bound to the other metals through NCS or CN bridges. These complexes, which retain the ReRe bonds of the parent dirhenium complexes, comprise the novel centrosymmetric complex [Re2Cl3(μ-dppE)2(CO)2(μ-NCS)]2Pd2(μ-SCN)(μ-NCS)Cl2 (9), and the trimetallic complexes Re2Cl3(μ-dppE)2(CO)2[(μ-NC)Ag(CN)] (10), Re2Cl3(μ-dppE)2(CO)2[(μ-NC)W(CO)5] (11), [Re2Cl3(μ-dppE)2(CO)2{(μ-NC)Pt(CN)(CN-t-Bu)2}]PF6 (12), [Re2Cl3(μ-dppE)2(CO)2{(μ-N(CN)2)Rh(CO)(PPh3)2}]O3SCF3 (13), and Re2Cl3(μ-dppm)2(CO)2[(μ-NC)W(CO)5] (16). The identities of 9 and 16 have been established by X-ray crystallography, and all complexes characterized by IR and NMR spectroscopy and cyclic voltammetry. The reactions of the dicarbonyl complex 1, and the isomeric pair of complexes Re2Cl4(μ-dppm)2(CO)(CNXyl), which have edge-sharing bioctahedral (ESBO) (3) and open bioctahedral (OBO) (4) geometries, with Na[N(CN)2] and K[C(CN)3] have been used to prepare complexes in which the uncoordinated CN groups have the potential to coordinate other mono- or dimetal units to form extended arrays. The complexes which have been prepared and characterized are the monosubstituted species Re2Cl3(X)(μ-dppE)2(CO)2 (X = N(CN)2 (14) or C(CN)3 (15)) and Re2Cl3(X)(μ-dppm)2(CO)(CNXyl) (X = N(CN)2 (17) or C(CN)3 (18) with ESBO structures; X = N(CN)2 (19) or C(CN)3 (20) with OBO structures), of which 15, 18, and 20 have been characterized by single-crystal X-ray structure determinations. The substitutional labilities of the Re−Cl bonds in the complexes Re2Cl4(μ-dppm)2(CO) (5), Re2Cl4(μ-dppm)2(CNXyl) (6), and Re2Cl4(μ-dppm)2 (7) toward Na[N(CN)2] and K[C(CN)3] have also been explored and the complexes Re2Cl3(X)(μ-dppm)2(CO) (X = N(CN)2 (21) or C(CN)3 (22)), Re2Cl3(X)(μ-dppm)2(CNXyl) (X = N(CN)2 (23) or C(CN)3 (24)), Re2Cl2(X)2(μ-dppm)2(CNXyl) (X = N(CN)2 (25) or C(CN)3 (26)), Re2[N(CN)2]4(μ-dppm)2 (27), and Re2[C(CN)3]4(μ-dppm)2 (28) isolated in good yield. Single-crystal X-ray structure determinations of 24, 26, and 27 have shown that the Re−Re triple bonds present in the starting materials 5−7 are retained in these products

Reactions of the Dirhenium(II) Complexes Re₂X₄(μ-dppm)₂ (X = Cl, Br; dppm = Ph₂PCH₂PPh₂) with Isocyanides. 21. A Comparison with the Complexes Re₂Cl₄(μ-dppE)₂ and Re₂Cl₄(μ-dcpm)₂ (dppE = Ph₂PC(CH₂)PPh₂; dcpm = Cy₂PCH₂PCy₂) and the Structural Characterization of Complexes of the Types Re₂Cl₄(μ-LL)₂(CNR), Re₂Cl₄(μ-LL)₂(CNR)₂, and [Re₂Cl₃(μ-LL)₂(CNR)₃]⁺ (LL = dppm, dppE, dcpm; R = <i>t</i>-Bu, Xyl)

A study of the reactions between the triply bonded dirhenium(II) complexes Re2Cl4(μ-LL)2, where LL = Ph2PCH2PPh2 (dppm), Ph2PC(CH2)PPh2 (dppE), or Cy2PCH2PCy2 (dcpm), with the isocyanides t-BuNC and XylNC (Xyl = 2,6-dimethylphenyl) show that complexes of the type Re2Cl4(μ-LL)2(CNR), Re2Cl4(μ-LL)2(CNR)2, and [Re2Cl3(μ-LL)2(CNR)3]+ are formed sequentially. Several of these have been structurally characterized by X-ray crystallography:  Re2Cl4(μ-dppm)2(CNXyl) (2), Re2Cl4(μ-dcpm)2(CNXyl) (11), Re2Cl4(μ-dppE)2(CN-t-Bu)2 (6), Re2Cl4(μ-dcpm)2(CN-t-Bu)2 (12), and [Re2Cl3(μ-dppE)2(CN-t-Bu)3]Cl (7). Complex 2 has an A-frame-like structure with a single μ-Cl bridging ligand, whereas for 11 the structure is like that of 2 but without this bridge, viz., Cl2Re(μ-dppm)2ReCl2(CNXyl) with a Re−Cl bond approximately collinear with Re⋮Re. The symmetrical complexes 6 and 12 are essentially isostructural and have an anti-arrangement of the two t-BuNC ligands. Complex 7 has the open bioctahedral structure [(t-BuNC)2ClRe(μ-dppE)2ReCl2(CN-t-Bu)]+, which is quite different from that of the edge-sharing bioctahedron found in salts of the [Re2Cl3(μ-dppm)2(CNXyl)3]+ cation and its neutral congener Re2Cl3(μ-dppm)2(CNXyl)3; preliminary crystallographic data for the latter compound show the structure to be (XylNC)ClRe(μ-Cl)(μ-CNXyl)(μ-dppm)2ReCl(CNXyl) with an all-cis arrangement of XylNC ligands. The Re−Re bond distances of 2, 6, 7, 11, and 12 occur in the range 2.289−2.380 Å and are consistent in all instances with the retention of a Re⋮Re bond, albeit weakened by some degree of Re→CNR(π*) back-bonding

Simple Cu(I) Complexes with Unprecedented Excited-State Lifetimes

This report describes new, readily accessible copper(I) complexes that can exhibit unusually long-lived, high quantum yield emissions in fluid solution. The complexes are of the form [Cu(NN)(POP)]+ where NN denotes 1,10-phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline (dmp) or 2,9-di-n-butyl-1,10-phenanthroline (dbp) and POP denotes bis[2-(diphenylphosphino)phenyl] ether. Modes of characterization include X-ray crystallography and cyclic voltammetry. The complexes each have a pseudotetrahedral coordination geometry and a Cu(II)/Cu(I) potential upward of +1.2 V vs Ag/AgCl. In room-temperature dichloromethane solution, charge-transfer excited states of the dmp and dbp derivatives exhibit respective emission quantum yields of 0.15 and 0.16 and corresponding excited-state lifetimes of 14.3 and 16.1 μs, respectively. Despite the fact that coordinating solvents usually quench charge-transfer emission from copper systems, the photoexcited dmp (dbp) complex retains a lifetime of 2.4 μs (5.4 μs) in methanol

Simple Cu(I) Complexes with Unprecedented Excited-State Lifetimes

This report describes new, readily accessible copper(I) complexes that can exhibit unusually long-lived, high quantum yield emissions in fluid solution. The complexes are of the form [Cu(NN)(POP)]+ where NN denotes 1,10-phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline (dmp) or 2,9-di-n-butyl-1,10-phenanthroline (dbp) and POP denotes bis[2-(diphenylphosphino)phenyl] ether. Modes of characterization include X-ray crystallography and cyclic voltammetry. The complexes each have a pseudotetrahedral coordination geometry and a Cu(II)/Cu(I) potential upward of +1.2 V vs Ag/AgCl. In room-temperature dichloromethane solution, charge-transfer excited states of the dmp and dbp derivatives exhibit respective emission quantum yields of 0.15 and 0.16 and corresponding excited-state lifetimes of 14.3 and 16.1 μs, respectively. Despite the fact that coordinating solvents usually quench charge-transfer emission from copper systems, the photoexcited dmp (dbp) complex retains a lifetime of 2.4 μs (5.4 μs) in methanol

Synthesis and Structural Characterization of Cu(I) and Ni(II) Complexes that Contain the Bis[2-(diphenylphosphino)phenyl]ether Ligand. Novel Emission Properties for the Cu(I) Species

The pseudotetrahedral complexes [Cu(NN)(DPEphos)]BF4, where DPEphos = bis[2-(diphenylphosphino)phenyl]ether and NN = 1,10-phenanthroline (1), 2,9-dimethyl-1,10-phenanthroline (2), 2,9-di-n-butylphenanthroline (3), or two dimethylcyanamides (4), and NiCl2(DPEphos) (5) have been synthesized and structurally characterized by X-ray crystallography and their solution properties examined by use of a combination of cyclic voltammetry, NMR spectroscopy, and electronic absorption spectroscopy. Complexes 1−4 possess a reversible Cu(II)/Cu(I) couple at potentials upward of +1.2 V versus Ag/AgCl. Compounds 1−3 exhibit extraordinary photophysical properties. In room-temperature dichloromethane solution, the charge-transfer excited state of the dmp (dbp) derivative exhibits an emission quantum yield of 0.15 (0.16) and an excited-state lifetime of 14.3 μs (16.1 μs). Coordinating solvents quench the charge-transfer emission to a degree, but the photoexcited dmp complex 2 retains a lifetime of over a microsecond in acetone, methanol, and acetonitrile

Simple Cu(I) Complexes with Unprecedented Excited-State Lifetimes

This report describes new, readily accessible copper(I) complexes that can exhibit unusually long-lived, high quantum yield emissions in fluid solution. The complexes are of the form [Cu(NN)(POP)]+ where NN denotes 1,10-phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline (dmp) or 2,9-di-n-butyl-1,10-phenanthroline (dbp) and POP denotes bis[2-(diphenylphosphino)phenyl] ether. Modes of characterization include X-ray crystallography and cyclic voltammetry. The complexes each have a pseudotetrahedral coordination geometry and a Cu(II)/Cu(I) potential upward of +1.2 V vs Ag/AgCl. In room-temperature dichloromethane solution, charge-transfer excited states of the dmp and dbp derivatives exhibit respective emission quantum yields of 0.15 and 0.16 and corresponding excited-state lifetimes of 14.3 and 16.1 μs, respectively. Despite the fact that coordinating solvents usually quench charge-transfer emission from copper systems, the photoexcited dmp (dbp) complex retains a lifetime of 2.4 μs (5.4 μs) in methanol