Darstellung und Reaktivität von {(η⁵‐C₅H₄SiMe₃)₂Ti(CCPh)₂}Ni(CO)

Abstract

Synthesis and Reactivity of {(q5-C5H,SiMe&Ti(C I CPh)3Ni(CO)*The synthesis and reactivity of {(q5-C5H4SiMe3),Ti-(C E CPh),}Ni(CO) (6) is described. (q5-C5H4SiMe3),Ti-(C = CPh), (1 a) reacts with equimolar amounts of Ni (C0)4 (5) to afford the dinuclear complex {(q5-C5H4SiMe&Ti-(C=CPh),}Ni(CO) (6) in 95% yield. In 6 both phenylethynyl units are q2-side-on-coordinated to the Ni(C0) moiety. When 6 is treated with HX or X2 (X = C1, Br) the Ti-C(alkyny1) o bond is cleaved, and the corresponding titanocene dihalides (q5-C5H4SiMe3)zTiXz (7) are formed. With PRR; [8a: R = R = 6 reacts by substitution of the nickel-bonded carbonyl ligand OMe; 8b: R = C=CPh, R' = Ph; 8~: R 7

Reaction Chemistry of Alkynyl-Functionalized Titanocenes. X-ray Structure Analyses of (η5-C5H4SiMe3)2Ti(Cl)(CH2SiMe3) and [(η5-C5H4SiMe3)2Ti(Cl)(C⋮CSiMe3)]CuBr

“…Thereby, the TiC⋮CSi entity is trans bent, which is typical for heterobimetallic compounds of the type {[Ti](C⋮CSiMe 3 ) 2 }CuR in which both alkynyl ligands are η 2 -bonded to a CuR moiety. − Through this deformation different copper-to-carbon bond lengths are observed [Cu(1)−C(11) = 2.012(9) Å and Cu(1)−C(12) = 2.102(8) Å; Table ]. Similar bonding situations are found in molecules of type {(η 5 -C 5 H 4 SiMe 3 ) 2 Ti(C⋮CR) 2 }MX [M = Ag, X = halide, pseudohalide, ,3b, X = organic ligand; ,4a,c MX = Ni(CO), Ni(PR 3 ), Ni[P(OR) 3 ]; , MX = Co(CO); , MX = FeCl 2 , CoCl 2 , NiCl 2 2,3a,4,27 ].…”

C2-Bridged Titanocene−Ferrocenyl Complexes: Synthesis, Reaction Chemistry, and Electrochemical Behavior

“…The η 2 -coordination of both FcC⋮C ligands to the Ni(CO) building block in compound 5 is clearly evidenced by the IR spectra: the C⋮C stretching vibration at 2055 cm -1 in 3 is shifted to 1876 cm -1 in 5 , thus indicating a bond weakening of the C⋮C triple bonds, which is typical for changes from noncoordinated to η 2 -coordinated alkynyl ligands . The ν(CO) band in 5 is observed at 2008 cm -1 (for comparison: ν(CO) in Ni(CO) 4 is 2052 cm -1 ) 6a…”

“…As in the latter compounds, the C 2 -bridged titanocene−ferrocenyl complex 3 exhibits linear TiC⋮CFc units (Figure ). The interatomic carbon−carbon distances of the C 2 building blocks in compound 3 (C(1)−C(2) = 1.227(13) Å, C(3)−C(4) = 1.21(2) Å) correspond to typical C⋮C separations found in organic as well as organometallic alkynes. 6a,, The Ti(1)−C(1) and Ti(1)−C(3) distances at 2.104(10) and 2.088(13) Å in 3 are similar to those found in (η 5 -C 5 H 4 SiMe 3 ) 2 Ti(C⋮CR) 2 (R = C 6 H 5 , 2.096(5) Å; R = SiMe 3 , 2.124(5), 2.103(5) Å 11a ). In comparison to titanium−carbon bonds, involving sp 3 - or sp 2 -hybridized carbon atoms, these bond lengths are remarkably shorter, indicating some π-conjugation between the d 0 early-transition-metal moiety [Ti] and the π-system of the alkynyl ligands FcC⋮C …”

“…Compound 5 is soluble in most of the common organic solvents and can be precipitated as a brown solid by cooling a toluene/ n -pentane solution to −40 °C. Compound 5 features a low-valent Ni(CO) entity with a nickel atom in a trigonal-planar environment. , Compounds of the type {[Ti](C⋮CR) 2 }NiL (R = singly bonded organic ligand; L = two-electron-donor ligand) represent well-studied and -characterized molecules. , …”

Synthesis, Characterization, and Reactivity of New Alkynyl Complexes of Rhodium and Iridium: Preparation of Neutral (M−M‘: M = Rh, Ir; M‘ = Pt, Pd) Hetero-Alkynyl-Bridged Dinuclear Complexes

“…In these planar dimers, the final tweezer-like or σ/π structures could be rationalized as the result of reducing steric congestion at the central core as a consequence of notable interactions between bulky ancillary ligands on Ni or Pt and alkyne substituents. Thus, whereas for bulky R = t Bu (ML n = PtPPh 3 ) 11d or SiMe 3 (ML n = NiPPh 3 ) 8d a σ/π bonding situation is formed, for R = SiMe 3 and ML n = Ni(CO) or [Cp 2 Ti(μ-σ:η 2 -C⋮CPh)(μ-σ:η 2 -C⋮CSiMe 3 )Ni(PPh 3 )] 8d a tweezer-like structure is favored. In the d 6 −d 8 heterodimetallic systems presented here the dimers exhibit nonplanar structures which would seem to allow substantial control of steric factors.…”