28796-10-3Relevant academic research and scientific papers
Synthese von [(η5-C5H5)2Ti(Cl)(CCSiMe3)]Ni(CO) und dessen Reaktionverhalten gegenueber Phosphiten: die Festkoerperstruktur von (CO)2Ni[P(OC6H4CH3-2)3]2
Meichel, E.,Stein, Th.,Kralik, J.,Rheinwald, G.,Lang, H.
, p. 191 - 198 (2007/10/03)
Treatment of [Ti](Cl)(CCSiMe3) (1) {[Ti]=(η5-C5H5)2Ti} with Ni(CO)4 (2) in a 1:1 molar ratio produces the heterobimetallic early-late transition metal complex {[Ti](Cl)(CCSiMe3)}Ni(CO) (3), which features a low-valent Ni(CO) entity stabilized by a datively bonded Cl and a η2-coordinated Me3SiCC ligand. As side-products [Ti]Cl2 (8) and {[Ti](CCSiMe3)2}Ni(CO) (5) are formed. The latter complex can also be synthesized by the reaction of [Ti](CCSiMe3)2 (4) with equimolar amounts of 2. If 3 is reacted with stoichiometric amounts of P(OR)3 (6a, R=C6H5; 6b, R=C6H4CH3-2; 6c, R=C6H4t-Bu-2) the bis(alkynyl) titanocene 4, (CO)2Ni[P(OR)3]2 (7a, R=C6H5; 7b, R=C6H4CH3-2; 7c, R=C6H4t-Bu-2), complex 8, {[Ti](μ,η1:η2-CCSiMe3)}2 (9) along with Me3SiCC-CCSiMe3 (10) is produced. A possible mechanism for the formation of these species is presented. The solid-state structure of 7b is reported. Complex 7b crystallizes in the tetragonalic space group P-421c with the following parameters: a=14.852(2), b=14.852(2), c=19.410(4) Angstroem, V=4281.5(12) Angstroem3, Z=4 and ρ=1.271 g cm-3. Mononuclear 7b features a Ni(O) centre in a pseudo-tetrahedral environment, caused by the CO and P(OC6H4CH3-2)3 ligands.
Stabilization of low-valent Ni(CO)-building blocks by [Ti] (C≡CR)2; reaction behavior of {[Ti](C≡CR)2}Ni(CO) towards triphenylphosphane and phosphites
Lang, H.,Meichel, E.,Stein, Th.,Weber, C.,Kralik, J.,et al.
, p. 150 - 160 (2008/10/08)
The preparation of heterobimetallic transition metal complexes of the type {[Ti](C≡CR)2}Ni(CO) {R = SiMe3: 3a, [Ti] = (η5-C5H5)2Ti; 3b: [Ti] = (Ti) a late (Ni) transition metal is present, is described. Additionally, the reaction chemistry of 3a and 3c towards P(OR′)3 (4a, R′ = CH3; 4b, R′ = C6H5; 4c, R′ = C6H4Me-2; 4d, R′ = C6H4tBu-2) is reported. In these reactions the nickel-bound carbonyl ligand is replaced by P(OR′) 3 producing {[Ti](C≡CSiMe3)2Ni[P (OR′)3] {[Ti] = (η5-C5 H5)2Ti: 5a, R′ = CH3; 5b, R′ = C6H5; 5c, R′ = C6 H4Me-2; [Ti] = (η5-C5H 4SiMe3)2Ti: 5d, R′ = CH3; 5e, R′ = C6H5} along with Ni(CO)2[P(OR′)3]2 (6a, R′ = C6H5; 6b, R′ = C6H 4Me-2; 6c, R′ = C6H4 tBu-2). It appeared that the latter reaction strongly depends on the sterical demand, Tolman cone angle, of the respective phosphites used: while, in the reaction of 3a or 3c with 4a selectively 5a and 5d is formed, with more bulky substituents R′, e.g. R′ = C6H5 and C6H 4Me-2, complexes 5b and 5c along with 6a and 6b are produced. Changing to even more sterical demanding groups such as R′ = C6H4tBu-2 than exclusively 6c is formed. The dynamic behaviour of 5 in solution is discussed. When 3a is treated with equimolar amounts of PPh3 (7) the titanium-nickel alkynyl species [Ti](μ-η1:η 2-C≡CSiMe3)Ni(PPh3)(μ-η 1:η2-C≡CSiMe3) {8a, [Ti] = (η5-C5H5)2Ti} is accessible via an alkynyl-transfer reaction from titanium to nickel. However, on treatment of 3c with 7 no reaction occurs. Arguments for the different behaviour of 3a-3c towards 4 and 7 will be presented. The result of the X-ray structure analysis of complexes 5d and 5e are reported. Both complex crystallize in the monoclinic space group P21/n. Cell parameters for 5d: a = 10.9390(10), b = 15.585(4), c = 22.950(3) A , β = 92.861(7)°, V = 3907.7(14) A 3, Z = 4 and δ = 1.189 g mol-1. 5e: a = 17.694(9), b = 22.620(10), c = 24.510(10) A , β = 103.90(4)°, V = 9523(8) A 3, Z = 8 and δ = 1.236 g mol-1. In both complexes a low-valent Ni[P(OR′)3] building block (5d, R′ = CH3; 5e, R′ = C6H5) is stabilised by the chelating effect of the organometallic ?-tweezer [Ti](C≡CSiMe3) 2, giving rise to a trigonal-planar environment at the nickel atom. The early (Ti) and late (Ni) transition metal centers are thereby bridged via the ?- and ?-bound alkynyl groups Me3 SiC≡C. The influence of the different sterical demanding phosphites onto the [Ti](C≡CSiMe3)2 framework will be discussed. 2002 Elsevier Science B.V. All rights reserved.
