Sequential reaction of the dimethylamino(ethynyl)carbene complex [(CO)5 WC(NMe2)CCH] (1) with nBuLi, CuI and BrCCSiMe3 affords the dimethylamino(trimethylsilylbutadiynyl)carbene [(CO)5WC(NMe2)CCCCSiMe3] (2). Desilylation of 2 with KF/THF/MeOH gives [(CO)5WC(NMe2)CCCCH] (3). The C‐stannylated carbene complex [(CO)5WC(NMe2)CCCCSnBu3] (4) is obtained by deprotonation of 3 with nBuLi and subsequent reaction with Bu3SnCl. Pd‐catalyzed coupling of complex 4 with [ClRu(CO),Cp] affords the heterobimetallic pentadiynylidene complex [(CO)5WC(NMe,)CCCCRu‐(CO)2Cp] (5) The analogous Fe derivative [(CO),WC(NMe,)CCCCFe(CO)2Cp] (6) is obtained by sequential reaction of 3 with nBuLi and [IFe(CO)2Cp] Similarly, treatment of 3 first with nBuLi and then with half an equivalent of HgCl2 affords the novel C4HgC4‐bridged biscarbene complex [(CO)3WC(NMe2)CCCCHgCCCCC(NMe2)W(CO)5]( 7 ) All new compounds are stable at room temperature. Spectroscopic data suggest weak interaction of the metal centers in 5 – 7.

The reaction of [(CO)5WC(Ph)H] with Me2NC⋮CNMe2 affords two complexes:  the binuclear complex [(CO)5WC(NMe2)(Me2N)CW(CO)5] (2) and the insertion product [(CO)5WC(NMe2)C(NMe2)C(Ph)H] (3). Sequential reaction of the (dimethylamino)ethynylcarbene complex [(CO)5WC(NMe2)C⋮CH] (4a) with nBuLi, W(CO)6, and F3CSO3Me yields the new ethynediyl-bridged binuclear alkoxycarbene−aminocarbene complex [(CO)5WC(NMe2)C⋮C(MeO)CW(CO)5] (5). Treatment of 4a and of [(CO)5CrC(NMe2)C⋮CH] (4b) with nBuLi and iodine gives the new iodine-substituted complexes [(CO)5MC(NMe2)C⋮CI] (M = W (6a), M = Cr (6b)). By Pd-catalyzed coupling of 6a,b with the C-stannylated ethynylcarbene complexes [(CO)5MC(NMe2)C⋮CSn(nBu)3] (7a,b) the butadiynediyl-bridged bis(carbene) complexes [(CO)5MC(NMe2)(C⋮C)2(Me2N)CM(CO)5] (8a,b) are obtained. Analogously, from [(CO)5WC(NMe2)(C⋮C) x H] (x = 2, 3) and nBuLi/I2 amino(iodobutadiynyl)carbene and amino(iodohexatriynyl)carbene complexes [(CO)5WC(NMe2)(C⋮C) x I] (x = 2 (10), 3 (14)) are obtained. Pd-catalyzed coupling with the corresponding C-stannylated alkynylcarbene complexes finally affords the binuclear C10(NMe2)2- and C14(NMe2)2-bridged complexes [(CO)5WC(NMe2)(C⋮C) x (Me2N)CW(CO)5] (x = 4 (12), 6 (16)). All alkynediyl-bridged bis(carbene) complexes are stable at room temperature. The spectroscopic data of 5 indicate that it is best described as a hybrid of a dipolar allenyl-type compound and an alkynylcarbene complex. In contrast, the C⋮C units in the binuclear complexes 8a,b, 12, and 16 are essentially localized.

No abstract

No abstract

The sequential reaction of two equivalents of the dimethylamino(ethynyl)carbene complexes [(CO)5M=C(NMe2)C≡CH] [M = W (1a), Cr (1b)] with two equivalents of nBuLi and one equivalent of a transition metal dichloride, [Cl2M′(Ln)], affords trinuclear biscarbene complexes of the type [(CO)5M=C(NMe2)C≡C−M′(Ln)−C≡CC(NMe)2=M(CO)5] [M′(Ln) = Ni(PEt3)2 (2a, b), Pd(PEt3)2 (3a, b), Pt(PEt3)2 (4a, b), Fe(dmpe)2 (6a), Hg (8a), Ti(η5‐C5H5)2 (9a, b)] [dmpe = 1,2‐bis(dimethylphosphino)ethane]. Treatment of 1a with equimolar amounts of first nBuLi and then [Cl2M′(Ln)] results in the formation of the monosubstitution products [(CO)5W=C(NMe2)C≡CM′(Ln)] [M′(Ln) = trans‐Pd(PEt3)2Cl (5a), trans‐Fe(dmpe)2Cl (7a)]. Additionally, the synthesis of the heterobimetallicethynylcarbene complex [(CO)5W=C(NMe2)C≡CPd(PEt3)2C≡CH] (10a), starting from 1a and [ClPd(PEt3)2C≡CH], is described. When three equivalents of 1a are treated, first with three equivalents of nBuLi and then with one equivalent of the trihalides PCl3 or BBr3, the novel tris(ethynylcarbene) complexes [{(CO)5W=C(NMe2)C≡C}3E] [E = B (11a), P (12a)] are obtained. The reaction of four equivalents of 1a,b with four equivalents of nBuLi, followed by addition of one equivalent of a group 14 tetrachloride [M′Cl4], yields the novel tetrakis(ethynylcarbene) complexes [{(CO)5M=C(NMe2)C≡C}4M′] [M′ = Si (13a, b), Ge (14a), Sn (15a, b)]. The complexes 8a, 9a, 12a, and 15a were characterized by X‐ray structural analyses. All spectroscopic and structural data suggest that the carbene fragments and the central transition metal or heteroatom in these new bis‐, tris‐, and tetrakis(ethynylcarbene) complexes interact only weakly.