Alkynyl complexes

Alkynyl complexes contain metal-carbon bonds in which the metal is bound to the sp-hybridized carbon at the terminus of a metal-carbon triple bond. The materials properties of these complexes have been investigated extensively. The properties of these complexes include luminescence, optical nonlinearity, electrical conductivity, and liquid crystallinity. These properties derive largely from the extensive overlap of the metal orbitals with the ir-orbitals on the alkynyl ligand. The M-C bonds in alkynyl complexes appear to be considerably stronger than those in methyl, phenyl, or vinyl complexes. Alkynyl complexes are sometimes prepared from acetylide anions generated from terminal alkynes and lithium bases (e.g., method A in Equation 3.42), but the acidity of alkynyl C-H bonds, particularly after coordination of the alkyne to the transition metal, makes it possible to form alkynyl complexes from alkynes and relatively weak bases (e.g., method B in Equation 3.42). Alkynyl copper complexes are easily prepared and often used to make alkynylnickel, -palladium, or -platinum complexes by transmetallation (Equation 3.43). This reaction is a step in the preparation of Ni, Pd, or Pt alkynyl complexes from an alkyne, base, and a catalytic amoimt of Cul (Equation 3.44). This protocol for 

CHAPTER 3 COVALENT (X-TYPE) LIGANDS BOUND THROUGH METAL-CARBON AND METAL-HYDROGEN BONDS 

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Alkene complexes Alkynyl complexes Ammine complexes Aqueous chemistry Arsine complexes Auranofin Auride ion Aurophilicity Binary compounds Bond lengths acetylacetonate complex alkyls and aryls ammine complexes carboxylates cyanide complexes dialkyl sulphide complexes dithiocarbamates to gold... 

Alkynyl complexes Fischer EO, Kalder HJ (1977) J Organomet Chem 131 57... 

The tendency to form ate complexes observed for yttrium is also seen in the preparation of a novel zirconium alkynyl complex. Reaction of Zr(Por)Cl2 (Por = OEP or TPP) with either two or three equivalents of LiC=CR (R = Ph or SiMe ) gives the trisalkynyl complexes Zr(Por)(C=CR)3Li(TFIF). An X-ray crystal structure of Zr(OEP)(C=CPh)2Li(THF) shows that all three alkynyl ligands are on... 

Complexes with unsaturated ligands (a-vinyl. a-allyl, and alkynyl) have been reported, each prepared from Fe(TPP)CI with the appropriate Grignard (vinyl, 2- methylvinyl.2,2-dimethylvinyl,allyl,or2-methylallyl)orlithiumreagent(LiC= C-n-Pr or LiC CPh) and observed by NMR spectroscopy (Scheme 4). The vinyl and alkynyl complexes are stable in solution at 25 C, whereas the allyl species decompose quickly if allowed to warm to room temperature. All were too reactive to be purihed by chromatography. The vinyl and allyl complexes show characteristic low spin behavior, although the temperature dependence of the vinyl... 

The low spin aryliron complexes Fe(Por)Ar behave differently than their alkyl counterparts toward oxygen. In chloroform the products of the reaction of Fe(Por)Ar with O2 are the iron(IV) alkyl Fe(Por)Ar] and Fe(Por)Cl, while in toluene the aryloxide complexes Fe(Por)OAr are formed with no direct evidence for the formation of arylperoxo intermediates."" The high spin iron(lll) alkynyl complexes which have more ionic character in the Fe—C bond do not react with oxygen, and the order of reactivity of organoiron(lll) complexes toward O2 is given by Fe(Por)(alkyl) > Fe(Por)(aryl) > Fe(Por)(C=CR). ... 

Syntheses and luminescence studies of mixed-metal gold(I)-copper(l) and -silver (I) alkynyl complexes. The tuming-on of emission upon d metal ion encapsulation. Dalton Transactions, 1830-1835. 

Yam VW-W, Wong KM-C (2005) Luminescent Molecular Rods - Transition-Metal Alkynyl Complexes. 257 1-32... 

Manna, Joseph, John, Kevin D., and Hopkins, Michael D., The Bonding of Metal-Alkynyl Complexes. 38 79... 

In favor of a dihydrogen intermediate, the following should be noted (i) the addition of HX molecules to OsHCl(CO)(P Pr3)2 is a useful synthetic route for dihydrogen compounds (vide infra), (ii) the electrophilic character of the dihydrogen complexes has been demonstrated,38 and (iii) the addition of electrophiles to metal alkynyl complexes is a general method of preparing vinylidene compounds.39... 

Although the Lewis basicity of the nitrogen atom of imines is weak, the bis-alkynyl complex Os(C2Ph)2(CO)(P Pr3)2 also coordinates benzophenone imine to give the six-coordinate bis-alkynyl complex Os(C2Ph)2(CO)(NH=CPh2)(PI Pr3)2,... 

The hydride-methyl complex OsH(Me)(CO)2(P Pr3)2 reacts with electrophilic reagents. The reaction products depend on the nature of the reagent (Scheme 39). Whereas the reaction with iodine gives almost quantitatively the diiodide OsI2(CO)2(P,Pr3)2, the reaction with a five-fold excess of phenylacetylene does not lead to the formation of the previously mentioned bis-alkynyl complex... 

A number of stable heterobimetallic copper alkyne complexes have been reported, based on the strategy of using another metal bis(alkynyl) complex as a chelating ligand for copper. The 1,4-diyne [(r -CsFGSiMe Ti-(C=GSiMe3)2]180 (or related complex) was found to stabilize the copper units GuX, with X = alkyl,180,181 vinyl,180... 

Although reports on silver(i) cr-alkynyl complexes have appeared for more than a century, the number of examples was still very limited prior to the past decade, and many of them were referred to as insoluble homoleptic polymeric [Ag(C=CR)]oo. Molecular alkynylsilver(i) complexes were often heteroleptic in nature and were achieved commonly through the stabilization by an extra coordination with strong cr-donor ligands such as amines, phosphines, and arsines. 

In addition to the well-known luminescent Re(NAN)(GO)3 moieties, the electrochemically active ferrocenyl groups were employed as building blocks for the construction of polynuclear silver(i) alkynyl complexes. Yip reported the synthesis, structural characterization, and electrochemistry of a tetranuclear complex, [Ag3(dppm)3(C=CFc)(OTf)]OTf 96 (Figure 43), with the Ag3(dppm)3 skeletal unit being capped by a ferrocenylethynyl ligand on one side and an OTP anion on the other, all in a /Z3-771-bonding mode.170... 

Figure 42 Decanuclear silver(i)—rhenium(i) alkynyl complexes 95a-d.

The main species in solution has been identified to be the hydrido-alkynyl complex [IrH(C2Ph)(cod)(//2-iPrPCH2CH2OMe)]+BF4 (23). This is, however, only a sink that results from direct reaction of 22 with the 1-alkyne, draining the active catalyst from the system. The catalysis proceeds via the dihydrido-diene intermediate [IrH2(cod)(//2- PrPCH2CH2OMe)]+ BF4 (24), which reacts reversibly with the alkyne to yield the hydrido-iridium-styryl complex 25, followed by a rate-determining reaction of this hydrido-vinyl species with hydrogen to re-... 

To conclude, we must consider that the Fe(I) oxidation state is also relatively unusual. Indeed, we have already mentioned that the reduction of a few 14-membered tetraaza-Fe(II) macrocycles leads to the corresponding Fe(I) complexes. Another example is given by the trigonal bipyramidal Fe(II)-alkynyl complex [Fe(PP3)(C=C-Ph)] + [PP3 = P(CH2CH2PPh2)3], Figure 72.118... 

From Vinylidene Complexes Generated from Alkynyl Complexes... 

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