CC CSiMe3 Research Articles

Synthesis and reactivity of an anionic allenylidene complex.

The reaction of [W([triple bond, length as m-dash]CC[triple bond, length as m-dash]CSiMe3)(CO)2(Tp*)] (Tp* = hydrotris(dimethylpyrazolyl)borate) with MeLi generates the first example of an anionic allenylidene complex Li[W([double bond, length as m-dash]C[double bond, length as m-dash]C[double bond, length as m-dash]CMeSiMe3)(CO)2(Tp*)] which reacts with electrophiles (H+, Me+) at the β-carbon to afford vinylcarbyne (allylidyne) complexes [W([triple bond, length as m-dash]CCE[double bond, length as m-dash]CMeSiMe3)(CO)2(Tp*)] (E = H, Me), and with bromine provides the unprecedented binuclear bis(carbyne) complex {C([double bond, length as m-dash]CMeSiMe3)C[triple bond, length as m-dash]W(CO)2(Tp*)}2via oxidative C-C coupling at the β-carbon.

Synthesis and reactivity of selenium functionalised allylidynes and propargylidynes.

The reactions of the trimethylsilylpropargylidyne [W([triple bond, length as m-dash]CC[triple bond, length as m-dash]CSiMe3)(CO)2(Tp*)] (1: Tp* = hydrotris(dimethylpyrazolyl)borate) towards selenium centred reagents when treated with tetrabutylammonium fluoride (TBAF) were explored in order to prepare alkynylselenolato propargylidynes, e.g., [W([triple bond, length as m-dash]CC[triple bond, length as m-dash]CSePh)(CO)2(Tp*)]. Treating 1 with TBAF and PhSeSePh resulted in E and Z isomers of the vinylcarbyne (allylidyne) complex [W{[triple bond, length as m-dash]CC(SePh)[double bond, length as m-dash]CHSePh}(CO)2(Tp*)] in addition to traces of the trisubstituted derivative [W{[triple bond, length as m-dash]CC(SePh)[double bond, length as m-dash]C(SePh)2}(CO)2(Tp*)]. Reactions with PhSeCl resulted in the isolation of bimetallic bis-substituted allylidyne complex [(Tp*)(CO)2W[triple bond, length as m-dash]CC(SePh)[double bond, length as m-dash]C(SePh)C[triple bond, length as m-dash]CC[triple bond, length as m-dash]W(CO)2(CO)2(Tp*)] as well as the desired selenolatopropargylidyne [W([triple bond, length as m-dash]CC[triple bond, length as m-dash]CSePh)(CO)2(Tp*)].

Further molecular engineering of diruthenium-(2-anilinopyridinate) alkynyl compounds through ligand design

A modified ap ligand, 2-(3,5-dimethoxyanilino)pyridine (HDiMeO ap) and its diruthenium compounds Ru 2(DiMeO ap) 4Cl ( 1), Ru 2(DiMeO ap) 4(C CC CSiMe 3) ( 2) and Ru 2(DiMeO ap) 4(C CC CSiMe 3) 2 ( 3) were prepared and characterized. New compounds Ru 2(MeO ap) 4(C CC CSiMe 3) x ( x = 1, 4; 2, 5; MeO ap is 2-(3-methoxyanilino)pyridinate) were prepared from the previously reported Ru 2(MeO ap) 4Cl. In addition, two related diruthenium compounds containing ferrocenyl acetylide ligand, Ru 2(MeO ap) 4(C CFc) ( 6) and Ru 2( ap) 4(C CC CFc) ( 7), were synthesized. Molecular structures of compounds 1, 2, 6 and 7 were established using single crystal X-ray diffraction study.

Some complexes containing carbon chains end-capped by M(CO) 2Tp′ [M = Mo, W; Tp′ = HB(pz) 3, HB(dmpz) 3] groups

Complexes M( CC CSiMe 3)(CO) 2Tp′ (Tp′ = Tp [HB(pz) 3], M = Mo 2, W 4; Tp′ = Tp ∗ [HB(dmpz) 3], M = Mo 3) are obtained from M( CC CSiMe 3)(O 2CCF 3)(CO) 2(tmeda) ( 1) and K[Tp′].Reactions of 2 or 4 with AuCl(PPh 3)/K 2CO 3 in MeOH afforded M{ CC CAu(PPh 3)}(CO) 2Tp′ (M = Mo 5, W 6) containing C 3 chains linking the Group 6 metal and gold centres.In turn, the gold complexes react with Co 3(μ 3-CBr)(μ-dppm)(CO) 7 to give the C 4-bridged {Tp(OC) 2M} CC CC {Co 3(μ-dppm)(CO) 7} (M = Mo 7, W 8), while Mo( CBr)(CO) 2Tp ∗ and Co 3{μ 3-C(C C) 2Au(PPh 3)}(μ-dppm)(CO) 7 give {Tp ∗(OC) 2Mo} C(C C) 2C {Co 3(μ-dppm)(CO) 7} ( 9) via a phosphine-gold(I) halide elimination reaction. The C 3 complexes Tp′(OC) 2M CC CRu(dppe)Cp ∗ (Tp′ = Tp, M = Mo 10, W 11; Tp′ = Tp ∗, M = Mo 12) were obtained from 2– 4 and RuCl(dppe)Cp ∗ via KF-induced metalla-desilylation reactions. Reactions between Mo( CBr)(CO) 2Tp ∗ and Ru{(C C) n Au(PPh 3)}(dppe)Cp ∗ ( n = 2, 3) afforded {Tp ∗(OC) 2Mo} C(C C) n {Ru(dppe)Cp ∗} ( n = 2 13, 3 14), containing C 5 and C 7 chains, respectively. Single-crystal X-ray structure determinations of 1, 2, 7, 8, 9 and 12 are reported.

Synthesis and structure of the diynyl complexes [Mo(C [tbnd]CC [tbnd]CR)L 2(η-C 7H 7)], L 2 = chelate N- or P-donor ligand, R = SiMe 3 or H: X-ray crystal structures of [Mo(C [tbnd]CC [tbnd]CSiMe 3)(2,2′-bipyridine)(η-C 7H 7)] and [Mo(C [tbnd]CC [tbnd]CH)(Ph 2PCH 2CH 2PPh 2)(η-C 7H 7)

The reaction of LiC CC CSiMe 3 with [MoBr( N– N)(η-C 7H 7)] in thf affords the diynyl complexes [Mo(C CC CSiMe 3)( N– N)(η-C 7H 7)], [ 1, N– N = 2,2′-bipyridine (bipy); 2, N– N=1,4- Bu 2 t -1,3-diazabutadiene (Bu t -dab)]; an analogous procedure yields [Mo(C CC CSiMe 3)(CO)(PPh 3)(η-C 7H 7)], 3 starting from [MoBr(CO)(PPh 3)(η-C 7H 7)]. Replacement of bipy in complex 1 with Ph 2PCH 2CH 2PPh 2 (dppe) in refluxing toluene gives [Mo(C CC CSiMe 3)(dppe)(η-C 7H 7)], 4. Proto-desilylation of 2 and 4 leads to formation of the unsubstituted diynyls [Mo(C CC CH)L 2(η-C 7H 7)] ( 5, L 2 = Bu t -dab; 6, L 2 = dppe). Cyclic-voltammetric studies in CH 2Cl 2 reveal that each of complexes 1, 2 and 4– 6 undergo reversible one-electron oxidation processes on the electrochemical time-scale. The X-ray crystal structures of complexes 1 and 6 are reported; the bipyridine complex 1, exhibits a π–π stacking interaction between the bipy ligands of adjacent molecules leading to a head-to-head interaction between diynyl ligands and a resultant substantial bending of the diynyl chain.

Synthesis, structures and some reactions of Ru(C [tbnd]CC [tbnd]CFc)(PP)Cp (PP = dppm, dppe) and related compounds

The compounds Ru(C CC CFc)(PP)Cp [PP = dppe ( 1), dppm ( 2)], have been obtained from reactions between RuCl(PP)Cp and FcC CC CSiMe 3 in the presence of KF ( 1) or HC CC CFc and K[PF 6] ( 2), both with added dbu. The dppe complex reacts with Co 2(CO) 6(L 2) [L 2 = (CO) 2, dppm] to give 3, 4 in which the Co 2(CO) 4(L 2) group is attached to the outer C C triple bond. The PPh 3 analogue of 3 ( 5) has also been characterised. In contrast, tetracyanoethene reacts to give two isomeric complexes 6 and 7, in which the cyano-olefin has added to either C C triple bond. The reaction of RuCl(dppe)Cp with HC CC CFc, carried out in a thf/NEt 3 mixture in the presence of Na[BPh 4], gave [Ru{C CC(NEt 3) CHFc}(dppe)Cp]BPh 4 ( 8), probably formed by addition of the amine to an (unobserved) intermediate butatrienylidene [Ru( C C C CHFc)(dppe)Cp] +. The reaction of I 2 with 8 proceeds via an unusual migration of the alkynyl group to the Cp ring to give [RuI(dppe){η-C 5H 4C CC(NEt 3) CHFc}]I 3 ( 9). Single-crystal X-ray structural determinations of 1, 2 and 4– 9 are reported.

Reaction of 1,3-diynes with the electron rich iron complex (η 5-C 5Me 5)(η 2-dppe)FeCl. A new and direct access to the iron butadiynyl complex (η 5-C 5Me 5)(η 2-dppe)FeCCCCSiMe 3

The electron rich iron complexes (C 5Me 5)Fe(dppe)Cl ( 3) and (C 5Me 5)Fe(dppe)Br ( 4) do not react with Li(CC) n SiMe 3 ( n=1, 2). Treatment of the chloro iron complex 3 with Me 3SiCCCCSiMe 3 in methanol and in the presence of NaBPh 4 provides the binuclear complex (C 5Me 5)(dppe)FeCCCCFe(dppe)(C 5Me 5) ( 10) as the unique product of this clean reaction (73%). Reaction of the chloro iron derivative 3 with one equivalent of trimethylsilyl(1,3-butadiyne) in triethylamine as a solvent and in the presence of NaBPh 4 yields 82% of the mononuclear iron trimethylsilyl-1,3-butadiyne compound. The triethylamine acts as a base to selectively deprotonate the putative butatrienylidene intermediate.

Synthesis and characterization of new transition metal diynyl complexes

The reaction of (η 5-C 5H 5)Mo(CO)(dppe)Cl with LiCCCCSiMe 3 yielded (η 5-C 5H 5)(CO)(dppe)MoCCCCSiMe 3 ( 1b) and, as a by-product (η 5-C 5H 5)Mo(CO)(dppe)Br ( 1a). Treatment of 1b with 0.2 equivalents of tetrabutylammonium fluoride or (η 5-C 5H 5)Mo(CO)(dppe)Cl with HCCCCH gave the terminal butadiyne complex (η 5-C 5H 5)(CO)(dppe)MoCCCCH ( 2). Complex 2 was deprotonated with sec-BuLi or lithium diisopropylamide, and the resulting anion (η 5-C 5H 5)(CO)(dppe)MoCCCCLi ( 3) was trapped with Me 3SiCl to regenerate 1b. The synthesis of Co 2(CO) 4L 2(μ-η 2-Me 3SiC 2CCSiMe 3) (L 2=dppa 4, 2PPh 2Me 5) compounds can be achieved by two methods: from Co 2(CO) 6(μ-dppa) by reaction with Me 3SiCCCCSiMe 3 in 1:1 ratio to yield 4, or from Co 2(CO) 6(μ-η 2-Me 3SiC 2CCSiMe 3) by reaction with dppa (1:1 ratio) and PPh 2Me (1:2 ratio) to yield 4 and 5, respectively. When the Co 2(CO) 4(μ-dppa)(μ-η 2-Me 3SiC 2CCSiMe 3) complex was treated with more Co 2(CO) 6(μ-dppa) the green di-substituted complex [Co 2(CO) 4(μ-dppa)] 2(μ-η 2:μ-η 2-Me 3SiC 2C 2SiMe 3) ( 6) was obtained. Desilylation of 4 with Bu 4NF gave Co 2(CO) 4(μ-dppa)(μ-η 2-Me 3SiC 2CCH) ( 7). All compounds synthesized have been characterized by analytical and spectroscopic data (IR, 1H-, 31P-, 13C-NMR, MS). In addition, compounds 1a and 4 were characterized by X-ray structure analysis.

Synthesis of triynylcarbene complexes and of bi- and trinuclear complexes with heptatriynylidene C 7-bridges

The dimethylamino(trimethylsilylhexatriynyl)carbene complex [(CO) 5WC(NMe 2)CCCCCCSiMe 3] ( 2) was synthesized by two different routes: (a) by sequential reaction of the ethynylcarbene complex [(CO) 5WC(NMe 2)CCH] with nBuLi, CuI, and ICCCCSiMe 3 and (b) by Cl 2Pd(MeCN) 2-catalyzed coupling of [(CO) 5WC(NMe 2)CCSn nBu 3] with ICCCCSiMe 3. Desilylation of 2 with KF/THF/MeOH afforded the hexatriynylcarbene complex [(CO) 5WC(NMe 2)CCCCCCH] ( 4). Deprotonation and coupling with ClSn nBu 3 gave the C-stannylated carbene complex [(CO) 5WC(NMe 2)CCCCCCSn nBu 3] ( 5). Reaction of 5 with nBuLi and [ClRu(CO) 2Cp] afforded the heterobimetallic heptatriynylidene-bridged complex [(CO) 5WC(NMe 2)CCCCCCRu(CO) 2Cp] ( 6). The trinuclear complex [(CO) 5WC(NMe 2)CCCCCC–Hg–CCCCCC(Me 2N)CW(CO) 5] ( 7) was obtained by reaction of 4 with nBuLi and HgCl 2. All new compounds are stable at room temperature. Spectroscopic data suggest weak interaction of the metal centers in 6 and 7.

Alkynyl and butadiynyl complexes of the cycloheptatrienylmolybdenum auxiliary Mo(CO) 2(η-C 7H 7)

The new alkynyl complexes [Mo(CCR)(CO) 2(η-C 7H 7)] ( 1, R=Bu t ; 2, R=SiMe 3; 3, R=CO 2Et) have been prepared by reaction of [MoBr(CO) 2(η-C 7H 7)] with alkynyl lithium ( 1, 2) or alkynyl copper ( 3) reagents. The σ-butadienyl complex [Mo{C(C(CN) 2)C(Ph)C(CN) 2}(CO) 2(η-C 7H 7)] 6, is formed by reaction of [Mo(CCPh)(CO) 2(η-C 7H 7)] with tetracyanoethene. Treatment of [MoBr(CO) 2(η-C 7H 7)] with LiCCCCSiMe 3 affords [Mo(CCCCSiMe 3)(CO) 2(η-C 7H 7)] 7 which is a precursor to [Mo(CCCCH)(CO) 2(η-C 7H 7)] 8 by desilylation with KF in methanol/THF. The butadiynyl complexes [Mo(CCCCH)(CO)L(η-C 7H 7)] ( 8, L=CO; 9, L=PMe 3) are also formed directly by reaction of [MoBr(CO)L(η-C 7H 7)] with Li 2CCCC in THF.

A titanium(III) tweezer complex with an embedded alkali metal ion between diynyl ligands: [(C 5HMe 4) 2Ti( η1−CCCCSiMe 3) 2] −[Li(THF) 2] +

The complex [( η 5−C 5HMe 4) 2Ti( η 1−CCCCSiMe 3) 2] −[Li(THF) 2] + ( 1) was obtained by the reaction of (C 5HMe 4) 2TiCl with 2 equiv. of LiCCCCSiMe 3 in THF. X-Ray crystal structure determination of 1 revealed that the lithium ion is embedded between the inner triple bonds of 4-trimethylsilyl-1,3-butadiyn-1-yl tweezer arms. The EPR spectrum of 1 shows a single line, ΔH = 2.5 G at g = 1.9940 (±0.0003), and coupling to 49Ti and 47Ti isotopes a (Ti) = 7.5 G.

Unsymmetrisch substituierte alkin- und dialkinkomplexe von wolfram(IV) und molybdän(IV). Die kristallstruktur von [W 2Cl 8(PhCCCCSiMe 3)(pyridin) 2

The unsymmetrically substituted alkyne ClCCSiMe 3 and the dialkynes PhCCCCSiMe 3 and PhCCSiMe 2CCPh react with tungsten hexachloride in CCl 4, in the presence of C 2Cl 4 as a reducing agent, and with molybdenum pentachloride in CCl 4, respectively, to form the alkyne complexes [MoCl 4-(ClCCiMe 3)] 2 ( 1), [WCl 4(ClCCSiMe 3)] 2 ( 2), [WCl 4(PhCCCCSiMe 3)] 2 ( 3), [W 2Cl 8(PhCCCCSiMe 3)] x ( 4), [W 2Cl 8(PhCCSiMe 2CCPh)] x ( 5), [Mo 2Cl 8-(PhCCSiMe 2CCPh)] x ( 6). In all cases the alkyne ligand is side-on coordinated to the metal (η 2), the bonding features correspond to the cyclopropene type. The coordination number of the metal is 7; the complexes 1–3 are dimerised via MCl 2M bridges and the bifunctional complexes 4–6 are polymerised via analogous bridges. In 3, the tungsten atom is coordinatd to the alkyne group adjacent to the phenyl substituent. In the molybdenum compounds the alkyne ligand is cleaved with Lewis bases such as pyridine or diethyl ether forming solvate complexes of molybdenum(IV), whereas in the corresponding tungsten complexes only the chloro bridges are cleaved. The pyridine adducts [W 2Cl 8(PhCCCCSiMe 3)(pyridine) 2] ( 7) and [W 2Cl 8(PhCCSiMe 2CCPh)(pyridine) 2] ( 8) are described in further detail. All complexes are characterized by elemental analyses, mass and IR spectra, the tungsten compounds (as ether adducts) also by their 13C NMR spectra. 7 was obtained in single crystals and has been subjected to a X-ray diffraction study. It crystallises in the monoclinic space group P2 1/ c with four formula units per unit cell (4154 independent, observed reflexions, R = 0.096) and with the lattice constants a 880.0(6), b 2866.0(20), c 1501.2(10) pm; β 94.4(3)°. EAch tungsten atom is surrounded by four chlorine atoms in equatorial positions, both alkyne groups are bonded side-on (η 2) to the tungsten atoms, whereas the N atoms of the pyridine molecules are located trans to the alkyne groups. The CC bond lengths of the alkyne groups are 125 pm (adjacent to the phenyl substituent) and 140 pm (adjacent to the SiMe 3 group), respectively. A strong trans-effect of the two alkyne groups is observed, resulting in shifting the tungsten atoms out of the Cl 4 planes by about 33 pm. The dihedral angle of 94.9°, enclosed by the two WC 2 planes, is remarkable.