Ag(I) dicarbene complexes [Ag(m)(L(n))m]X(m) (L(n) = Im(Me)(CH2)(n)Im(Me), Im(Me) = N-methylimidazol-N-yl-2-ylidene; n = 3, X = PF6, m = 2; n = 6-8, 10, X = AgBr2, m = 1, 2) were prepared by reacting Ag2O with 1 equiv of the corresponding bisimidazolium salt [H2L(n)]A2 (A = PF6, Br). The dibromoargentates react with 1 equiv of AgTfO to afford [Ag(m)(L(n))m](TfO)m (m = 1, 2). The room temperature transmetalation reaction of [Ag(m)(L(n))m][AgBr2]m (n = 3, 5, 6-8, 10) with [AuCl(SMe2)] and AgTfO (L(n):Au:TfO = 1:1:1) affords [Au2(μ-L(n))2](TfO)2 (n = 3, 5, 10), or mixtures of [Au(κ(2)-L(n))]TfO (main product for n = 7) and [Au2(μ-L(n))2](TfO)2 (main product for n = 6, 8). At room temperature, the equilibrium between [M2(μ-L(n))2](TfO)2 and [M(κ(2)-L(n))]TfO is fast for M = Ag, but slow for M = Au, in the NMR time scale. When n ≥ 7 and M = Ag or Au, the equilibrium is shifted toward the mononuclear complexes in the order 8 > 10 > 7, which proves that the (CH2)8 linker has the optimal length for trans chelation. Correspondingly, the high-temperature metalation of [H2L(n)]Br2 (n = 8, 10) with 1 equiv of [AuCl(SMe2)] and excess of NaAcO, affords [Au(κ(2)-L(n))]Br with a small amount of [Au2(μ-L(n))2]Br2. If AgTfO is added to the reaction mixture, [Au(κ(2)-L(8))]2[AgBr3] is isolated instead of the desired triflate, which can be obtained by reacting the mixture of [Au(κ(2)-L(8))]Br and [Au2(μ-L(8))2]Br2 with AgTfO. [Au(κ(2)-L(10))]TfO was isolated after thermal conversion of [Au2(μ-L(10))2](TfO)2. [Au(κ(2)-L(8))]TfO reacts with I2 to give trans-[AuI2(κ(2)-L(8))]TfO, which is the first Au(III) complex containing a trans-spanning bidentate ligand. We have determined the crystal structures of complexes [Ag2(μ-L(3))2](PF6)2, [Ag(κ(2)-L(7))]TfO, [Au2(μ-L(3))2](TfO)2, [Au(κ(2)-L(8))]Br, [Au(κ(2)-L(8))]2[AgBr3], and trans-[AuI2(κ(2)-L(8))]TfO.

A series of dinuclear alkynyl gold(I) complexes of the type [(AuCCR′) 2 {μ-(Im-R) 2 (CH 2 ) n }] (R′ = t Bu, SiMe 3 , Ph, C 6 H 4 X-4 (X = OMe, CF 3 , or NO 2 ), 3-pyridyl (Pyl), 2,2′-bipyridin-5-yl (Bpyl); Im-R = N-methylimidazol-N-yl-2-ylidene (Im-Me), N-butylimidazol-N-yl-2-ylidene (Im-Bu), Nbenzylimidazol-N-yl-2-ylidene (Im-Bz); n = 1, 3, 5) have been synthesized by (1) deprotonation of arylacetylenes with K 2 CO 3 in the presence of [(AuCl) 2 {μ-(Im-R) 2 (CH 2 ) n }], (2) the "acac method", i.e., the reaction of [(AuCl) 2 {μ-(Im-R) 2 (CH 2 ) n }] with Tl(acac) and, subsequently, with HCCR′, and (3) the reaction of [Au(CCR′)] n with [(AgBr) 2 {μ-(Im-R) 2 (CH 2 ) n }]. In addition, mononuclear complexes [(AuCCR′)(Im-R 2 )], where Im-R 2 = N,N′-dimethylimidazol-2-ylidene and R′ = SiMe 3 or Im-R 2 = N,N′-dibenzylimidazol-2-ylidene and R′ = t Bu, have been prepared by method 2 or 3, respectively. A dinuclear complex containing two AuCl units connected by an acyclic dicarbene ligand results from the attack of N,N′-diethylpropylenediamine to the isocyanide ligand of [AuCl(CN t Bu)]. The photophysical properties of the new gold(I) chloro and alkynyl bis(carbene) complexes have been studied. Most of the dinuclear alkynyl complexes prepared are emissive at room temperature in the solid state or in solution. Complexes derived from aryl-or heteroarylalkynes give structured emissions that have been assigned to gold-perturbed intraligand 3 [π→π*](CCAr) excited states.

The reaction of the organogold metallaligand [(AuC[triple bond]Cbpyl)(2)(mu-Ph(2)P(CH(2))(4)PPh(2))] (bpyl = 2,2'-bipyridin-5-yl) with Fe(2+) or Zn(2+) ions gave helicates where the three ligand strands adopt a unique looped geometry.

New gold(I) alkynyl metalloligands bpylCCAuL, bpyl'CCAuPPh3 , and PPN[Au(CCbpyl')2 ] (bpyl or bpyl'=2,2'-bipyridin-5-yl or -4-yl, respectively; L=PMex Ph3-x (x=1-3), P(C6 H3 Me2 -3,5)3 , PCy3 , XyNC) have been synthesized. Ligands bpylCCH and metalloligands bpylCCAuL (L=PPh3 , PMePh2 , PCy3 , CNXy) react with MX2 (M=Fe, Zn, X=ClO4 ; M=Co, X=BF4 ) to give complexes [M(bpylCCZ)3 ]X2 (Z=H or AuL). In most cases, these complexes are mixtures of fac and mer isomers in a statistical distribution, in both CH2 Cl2 and MeCN. However, for L=PPh3 , the fac isomer is dominant in MeCN. NMR and ESI-MS studies, together with the crystal structure of [Co(bpylCCAuPPh3 )3 ](BF4 )2 , suggest that this solvent dependence is originated by the formation of helical dimers between two fac complexes in MeCN. These dimers are stabilized by solvophobic effects and multiple intermolecular interactions. Complex [Fe(Ph3 PAuCCbpdiylCCAuPPh3 )3 ](ClO4 )2 (bpdiyl=2,2'-bipyridin-5,5'-diyl) was obtained by reaction of three diauro diethynylbipyridines and Fe(ClO4 )2 .

Alkynyl gold(I) metallaligands [(AuC≡Cbpyl)2(μ-diphosphine)] (bpyl=2,2'-bipyridin-5-yl; diphosphine=Ph2P(CH2)(n)PPh2, [n=3 (L(Pr)), 4 (L(Bu)), 5 (L(Pent)), 6 (L(Hex))], dppf (L(Fc)), Binap (L(Binap)) and Diop (L(Diop))) react with MX2 (M=Fe, Zn, X=ClO4; M=Co, X=BF4) to give triple helicates [M2(L(R))3]X4. These complexes, except those containing the semirigid L(Binap) metallaligand, present similar hydrodynamic radii (determined by diffusion NMR spectroscopy measurements) and a similar pattern in the aromatic region of their (1)H NMR spectra, which suggests that in solution they adopt a compact structure where the long and flexible organometallic strands are folded. The diastereoselectivity of the self-assembly process was studied by using chiral metallaligands, and the absolute configuration of the iron(II) complexes with L(Binap) and L(Diop) was determined by circular dichroism spectroscopy (CD). Thus, (R)-L(Binap) or (S)-L(Binap) specifically induce the formation of (Δ,Δ)-[Fe2((R)-L(Binap))3](ClO4)4 or (Λ,Λ)-[Fe2((S)-L(Binap))3](ClO4)4, respectively, whereas (R,R)- or (S,S)-L(Diop) give mixtures of the ΔΔ- and ΛΛ-diastereomers. The ΔΔ helicate diastereomer is dominant in the reaction of Fe(II) with (R,R)-L(Diop), whereas the ΛΛ isomer predominates in the analogous reaction with (S,S)-L(Diop). The photophysical properties of the new dinuclear alkynyl complexes and the helicates have been studied. The new metallaligands and the [Zn2(L(R))3](4+) helicates present luminescence from [π→π*] excited states mainly located in the C≡Cbpyl units.