Syntheses and Chemistry of the Diynyl Complexes M(C⋮CC⋮CH)(CO)₃(η-C₅H₅) (M = Mo, W):  Crystal Structures of W(C⋮CC⋮CSiMe₃)(CO)₃(η-C₅H₅), W{C⋮CC[CH=C(CN)₂]=C(CN)₂}(CO)₃(η-C₅H₅), andcis-W(C⋮CPh)(CO)₂(PPh₃)(η-C₅H₅)

Abstract

Reactions of buta-1,3-diyne with appropriate metal halides, carried out in the presence of CuI in NHEt2, have given high yields of M(C⋮CC⋮CH)(CO) n Cp [M = W (1-W), Mo (1-Mo), n = 3; M = Fe, n = 2 (2)]. Complex 1-W was metalated with LiNPri 2; subsequent reactions with SiClMe3 or PClPh2 gave W(C⋮CC⋮CR)(CO)3Cp [R = SiMe3 (3) or P(O)Ph2 (4)] in modest to high yield. Coupling of 1 with iodoarenes, catalyzed by a mixed CuI−Pd0 catalyst, gave M(C⋮CC⋮CAr) (CO)3Cp [M = W, Ar = Ph (5-W), tol (6), C6H4OMe-4 (7), C6H4CO2Me-4 (8); M = Mo, Ar = Ph (5-Mo)]. Oxidative coupling of 1 (CuCl-tmed-O2) gave {M(CO)3Cp}2(μ-C8) [M = W (9-W), Mo (9-Mo)]. Addition of tetracyanoethene to 1-W occurred at the C⋮C triple bond further from the metal atom, to give W{C⋮CC[=C(CN)2]CHC(CN)2}(CO)3Cp (10). Substitution of CO by PPh3 was difficult, but the Me3NO-induced reaction with 5-W afforded cis-W(C⋮CC⋮CPh)(CO)2(PPh3)Cp (11) in low yield. The X-ray crystal structures of 3 and 10, together with that of cis-W(C⋮CPh)(CO)2(PPh3)Cp (12), are reported.

Electronic Structure and Chain‐Length Effects in Diplatinum Polyynediyl Complexes trans,trans‐[(X)(R3P)2Pt(CC)nPt(PR3)2(X)]: A Computational Investigation

“…These have the highest bond order of all triple bonds but remain longer than the C3/C4 triple bonds. Upon going from PtC 4 Pt to PtC 26 Pt, the PtCC bond orders drop from 2.782 to 2.727 (2.00 %), in accord with the bond-length trend noted above. Inspection of the natural populations shows that this decrease is due to electron depletion in the p bonding orbitals and increased occupancy of the p* antibonding orbitals.…”

“…[10][11][12] As the spcarbon chain is lengthened, progressively more intense and longer wavelength absorptions are observed. In an effort to better understand the origin of these absorptions, time-dependent DFT calculations were performed for PtC 4 Pt through to PtC 10 Pt. Figure 4 depicts the simulated absorption spectra, each of which features two bands.…”

“…For PtC 4 Pt, band I is essentially single configurational and corresponds to a HOMO-LUMO excitation. For the higher homologues, band I becomes increasingly two-configurational, but retains dominant HOMO-LUMO character.…”

“…In contrast, the HOMO energies of HC x H increase with chain length; the origin of this dichotomy is analyzed. The electronic spectra of PtC 4 Pt to PtC 10 Pt are simulated. These consist of two p-p* bands that redshift with increasing chain length and are closely paralleled by real systems.…”

Metall‐Alkinyl‐σ‐Komplexe: Synthesen und Materialien

“…[122] Mit einer katalytischen Menge an [PdCl 2 (CH 3 CN) 2 ] in DMF (5 Mol-%) war auf diese Weise eine Reihe von Alkinylkomplexen zugänglich, darunter auch einige Heterodimetallkomplexe (Schema 45 b). In einer zur Synthese von Re-Polyindiylen analogen Synthese erhielten Bruce et al [210] eine Serie ungesättigter C n -Ketten, die an beiden Enden mit gleichen oder unterschiedlichen ML n -Gruppen komplexiert sind. Buta-1,3-diin erwies sich als geeigneter Ligand, der außerdem leicht substituierbar ist.…”