A Novel Example of the Reductive Cyclization of a Diyne at a Re−Re Triple Bond: The Reaction of Re₂Cl₄(μ-dppm)₂ with 1,7-Octadiyne

The triply bonded dirhenium(II) complex Re2Cl4(μ-dppm)2 (1; dppm = Ph2PCH2PPh2) reacts with 1,7-octadiyne to produce the novel dirhenium(III) complex Re2Cl3(μ,η2-C8H7)(μ-dppm)2 (2). The dirhenium complex 1 serves both as a reagent for the 2-electron reductive cyclization of the diyne and as the template to stabilize the resulting [C8H7Re2] bridging unit, which is of a type not previously encountered in multiple bond dimetal chemistry

Reactions of the Dirhenium(II) Complexes Re₂X₄(μ-dppm)₂ (X = Cl, Br; dppm = Ph₂PCH₂PPh₂) with Isocyanides. 16. Complexes of the Type [Re₂(μ-Br)₂(μ-dppm)₂Br(CO)(CNXyl)₂]Y (Y = O₃SCF₃, PF₆) That Exist in Isomeric Forms with Boat and Chair Conformations for the [Re₂(μ-dppm)₂] Unit

Reactions of the Dirhenium(II) Complexes Re2X4(μ-dppm)2 (X = Cl, Br; dppm = Ph2PCH2PPh2) with Isocyanides. 16. Complexes of the Type [Re2(μ-Br)2(μ-dppm)2Br(CO)(CNXyl)2]Y (Y = O3SCF3, PF6) That Exist in Isomeric Forms with Boat and Chair Conformations for the [Re2(μ-dppm)2] Uni

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

Reactions of the Dirhenium(II) Complexes Re₂X₄(μ-dppm)₂ (X = Cl, Br; dppm = Ph₂PCH₂PPh₂) with Isocyanides. 19. Studies of the Reactions of Five Structural Isomers of Re₂Cl₂(μ-dppm)₂(CO)(CNXyl)₃ That Lead to the Dirhenium(I) Complexes [Re₂(μ-Cl)(μ-CO)(μ-dppm)₂(CNXyl)₄]O₃SCF₃ and [Re₂Cl(μ-dppm)₂(CO)(CNXyl)₃(NCCH₃)]O₃SCF₃

Three of the five known isomers of Re2Cl2(μ-dppm)2(CO)(CNXyl)3 (labeled 4‘ ‘−8‘ ‘ in accord with earlier work) react with 1 equiv each of XylNC and TlO3SCF3 in benzene to produce the symmetrical dirhenium(I) complex [Re2(μ-Cl)(μ-CO)(μ-dppm)2(CNXyl)4]O3SCF3 (I) in good yield. Isomers 4‘ ‘, 6‘ ‘, and 8‘ ‘ are converted to I, while 5‘ ‘ gives an unidentified mixture and isomer 7‘ ‘ is unreactive. When the reactions of 4‘ ‘, 5‘ ‘, 6‘ ‘, and 8‘ ‘ with TlO3SCF3 are carried out in acetonitrile in the absence of XylNC, the compound [Re2Cl(μ-dppm)2(CO)(CNXyl)3(NCCH3)]O3SCF3 can be isolated in three stable isomeric forms (A−C). Isomer B is unreactive, while A and C react with XylNC in benzene to afford I. Single-crystal X-ray structure determinations have been carried out on compounds I and B

Reactions of the Dirhenium(II) Complexes Re₂X₄(dppm)₂ (X = Cl, Br; dppm = Ph₂PCH₂PPh₂) with Isocyanides. 10. Synthesis and Characterization of the Complex [Re₂Br₃(μ-dppm)₂(CO)₂(CNXyl)]O₃SCF₃ and Several Isomeric Forms of [Re₂Br₃(μ-dppm)₂(CO)(CNXyl)₂]Y (Y = PF₆, O₃SCF₃)^†

The reactions of the unsymmetrical, coordinatively unsaturated dirhenium(II) complexes [Re2Br3(μ-dppm)2(CO)(CNXyl)]Y (XylNC = 2,6-dimethylphenyl isocyanide; Y = O3SCF3 (3a), PF6 (3b)) with XylNC afford at least three isomeric forms of the complex cation [Re2Br3(μ-dppm)2(CO)(CNXyl)2]+. Two forms have very similar bis(μ-halo)-bridged edge-sharing bioctahedral structures of the type [(CO)BrRe(μ-Br)2(μ-dppm)2Re(CNXyl)2]Y (Y = O3SCF3 (4a/4a‘), PF6 (4b/4b‘)), while the third is an open bioctahedron [(XylNC)2BrRe(μ-dppm)2ReBr2(CO)]Y (Y = O3SCF3 (5a), PF6 (5b)). While the analogous chloro complex cation [Re2Cl3(μ-dppm)2(CO)(CNXyl)2]+ was previously shown to exist in three isomeric forms, only one of these has been found to be structurally similar to the bromo complexes (i.e. the isomer analogous to 5a and 5b). The reaction of 3a with CO gives the salt [Re2Br3(μ-dppm)2(CO)2(CNXyl)]O3SCF3 (7), in which the edge-sharing bioctahedral cation [(XylNC)BrRe(μ-Br)(μ-CO)(μ-dppm)2ReBr(CO)]+ has an all-cis arrangement of π-acceptor ligands. The Re−Re distances in the structures of 4b‘, 5a, and 7 are 3.0456(8), 2.3792(7), and 2.5853(13) Å, respectively, and accord with formal Re−Re bond orders of 1, 3, and 2, respectively. Crystal data for [Re2Br3(μ-dppm)2(CO)(CNXyl)2](PF6)0.78(ReO4)0.22·CH2Cl2 (4b‘) at 295 K:  monoclinic space group P21/n (No. 14) with a = 19.845(4) Å, b = 16.945(5) Å, c = 21.759(3) Å, β = 105.856(13)°, V = 7038(5) Å3, and Z = 4. The structure was refined to R = 0.060 (Rw = 0.145) for 14 245 data (Fo2 > 2σ(Fo2)). Crystal data for [Re2Br3(μ-dppm)2(CO)(CNXyl)2]O3SCF3·C6H6 (5a) at 173 K:  monoclinic space group P21/n (No. 14) with a = 14.785(3) Å, b = 15.289(4) Å, c = 32.067(5) Å, β = 100.87(2)°, V =7118(5) Å3, and Z = 4. The structure was refined to R = 0.046 (Rw = 0.055) for 6962 data (I > 3.0σ(I)). Crystal data for [Re2Br3(μ-dppm)2(CO)2(CNXyl)]O3SCF3·Me2CHC(O)Me (7) at 295 K:  monoclinic space group P21/n (No. 14) with a = 14.951(2) Å, b = 12.4180(19) Å, c = 40.600(5) Å, β = 89.993(11)°, V = 7537(3) Å3, and Z = 4. The structure was refined to R = 0.074 (Rw = 0.088) for 6595 data (I > 3.0σ(I))

Reactions of the Dirhenium(II) Complexes Re₂X₄(μ-dppm)₂ (X = Cl, Br; dppm = Ph₂PCH₂PPh₂) with Isocyanides. 16. Complexes of the Type [Re₂(μ-Br)₂(μ-dppm)₂Br(CO)(CNXyl)₂]Y (Y = O₃SCF₃, PF₆) That Exist in Isomeric Forms with Boat and Chair Conformations for the [Re₂(μ-dppm)₂] Unit

Reactions of the Dirhenium(II) Complexes Re2X4(μ-dppm)2 (X = Cl, Br; dppm = Ph2PCH2PPh2) with Isocyanides. 16. Complexes of the Type [Re2(μ-Br)2(μ-dppm)2Br(CO)(CNXyl)2]Y (Y = O3SCF3, PF6) That Exist in Isomeric Forms with Boat and Chair Conformations for the [Re2(μ-dppm)2] Uni

The First Example of Isomerization of a Dimetal Complex Involving the Switch of a Metal−Metal Bond Order from 3 to 0. Synthesis and Characterization of the Paramagnetic Mixed-Valence Complex Cation [(XylNC)(OC)Re(μ-Cl)₂(μ-dppm)₂ReCl(CNXyl)]⁺ ¹

The First Example of Isomerization of a Dimetal Complex Involving the Switch of a Metal−Metal Bond Order from 3 to 0. Synthesis and Characterization of the Paramagnetic Mixed-Valence Complex Cation [(XylNC)(OC)Re(μ-Cl)2(μ-dppm)2ReCl(CNXyl)]+ 1</sup

Resistance of the [Re₂(μ-dppm)₂]⁴⁺ Core (dppm = Ph₂PCH₂PPh₂) to Cleavage by π-Acceptor Ligands. Novel Isomers of the [Re₂Cl₂(μ-dppm)₂(CO)(CNxyl)₃]²⁺ Cation¹

Resistance of the [Re2(μ-dppm)2]4+ Core (dppm = Ph2PCH2PPh2) to Cleavage by π-Acceptor Ligands. Novel Isomers of the [Re2Cl2(μ-dppm)2(CO)(CNxyl)3]2+ Cation1</sup

Reactions of the Dirhenium(II) Complexes Re₂X₄(μ-dppm)₂ (X = Cl, Br; dppm = Ph₂PCH₂PPh₂) with Isocyanides. 13. Identification of a New Structural Isomer of the Dirhenium Cation [Re₂Cl₃(μ-dppm)₂(CO)(CNXyl)₂]⁺ and Its Isomerization Behavior. Structural Characterization of (XylNC)ClRe(μ-Cl)(μ-CNXyl)(μ-dppm)₂ReCl(CO)

A yellow form of the dirhenium salts of the type [Re2Cl3(μ-dppm)2(CO)(CNXyl)2]Y (Y = Cl, O3SCF3, PF6, ReO4) has been shown to have the μ-CNXyl-bridged structure [(XylNC)ClRe(μ-Cl)(μ-CNXyl)(μ-dppm)2ReCl(CO)]+ on the basis of an X-ray crystal structure determination of its neutral paramagnetic congener. The Re−Re bond length in the structure of Re2Cl3(μ-dppm)2(CO)(CNXyl)2 is 2.7155(9) Å, in accord with the presence of a formal Re−Re bond order of 1.5. This particular cation constitutes the fourth isomer of [Re2Cl3(μ-dppm)2(CO)(CNXyl)2]+ to have been structurally characterized

The First Example of Isomerization of a Dimetal Complex Involving the Switch of a Metal−Metal Bond Order from 3 to 0. Synthesis and Characterization of the Paramagnetic Mixed-Valence Complex Cation [(XylNC)(OC)Re(μ-Cl)₂(μ-dppm)₂ReCl(CNXyl)]⁺ ¹

The First Example of Isomerization of a Dimetal Complex Involving the Switch of a Metal−Metal Bond Order from 3 to 0. Synthesis and Characterization of the Paramagnetic Mixed-Valence Complex Cation [(XylNC)(OC)Re(μ-Cl)2(μ-dppm)2ReCl(CNXyl)]+ 1</sup