TY - JOUR
T1 - Thermally or photochemically induced reductive cleavage of metal-metal bonds of metal carbonyl dimers by a titanocene(III) tert-butoxide
T2 - Novel reversible access to heterobimetallic complexes
AU - Matsubara, Kouki
AU - Niibayashi, Shota
AU - Nagashima, Hideo
PY - 2003/3/31
Y1 - 2003/3/31
N2 - Novel synthetic methods for Ti Mo, Ti-W, and Ti-Ru heterobimetallic complexes are established by the reaction of a certain titanium(III) alkoxide and the corresponding metal carbonyl dimer, [CpM(CO)n]2 [M = Mo, W (n = 3); M = Ru (n = 2)]. Thus, a novel monomeric titanium complex, Cp2Ti(OtBu) (1), which is synthesized from Cp2TiCl and KOtBu and characterized by spectroscopy and crystallography, smoothly reacts with [CpM(CO)3]2 (M = Mo (2a), W (2b)) to give heterobimetallic complexes, Cp2Ti(OtBu)(u-OC)M(CO)2Cp (M = Mo (3a) and W (3b)), of which two metallic moieties are linked by the isocarbonyl bridge. Similar reaction of 1 with [CpRu(CO)2]2 (4) does not occur thermally, but is accomplished under photoirradiation to afford Cp2(OtBu)Ti-Ru(CO)2Cp (5), of which two metallic moieties are linked by a direct metal-metal bond. Use of 1 is particularly important for these reactions; other titanium alkoxides such as [Cp2Ti(OMe)]2 and Cp2Ti[O(2,6-tBu2-4-Me)C6H2] do not react with the metal carbonyl dimers. An interesting feature of these new heterobimetallic complexes, 3a, 3b, and 5, is the existence of the thermal fragmentation process to regenerate the starting materials: 3a or 3b is actually in equilibrium with a mixture of 1 and 2a or 1 and 2b, respectively [ΔG298k0 = -4.1 ± 0.2 kcal mol-1 (3a), -4.3 ± 0.2 kcal mol-1 (3b)]. The Ti-Ru compound 5 thermally undergoes fragmentation to regenerate 1 and 4. The formation of these heterobimetallic complexes is formally considered as the metal-metal bond cleavage of metal carbonyl dimers by a Ti(III) reducing reagent; possible mechanisms are discussed.
AB - Novel synthetic methods for Ti Mo, Ti-W, and Ti-Ru heterobimetallic complexes are established by the reaction of a certain titanium(III) alkoxide and the corresponding metal carbonyl dimer, [CpM(CO)n]2 [M = Mo, W (n = 3); M = Ru (n = 2)]. Thus, a novel monomeric titanium complex, Cp2Ti(OtBu) (1), which is synthesized from Cp2TiCl and KOtBu and characterized by spectroscopy and crystallography, smoothly reacts with [CpM(CO)3]2 (M = Mo (2a), W (2b)) to give heterobimetallic complexes, Cp2Ti(OtBu)(u-OC)M(CO)2Cp (M = Mo (3a) and W (3b)), of which two metallic moieties are linked by the isocarbonyl bridge. Similar reaction of 1 with [CpRu(CO)2]2 (4) does not occur thermally, but is accomplished under photoirradiation to afford Cp2(OtBu)Ti-Ru(CO)2Cp (5), of which two metallic moieties are linked by a direct metal-metal bond. Use of 1 is particularly important for these reactions; other titanium alkoxides such as [Cp2Ti(OMe)]2 and Cp2Ti[O(2,6-tBu2-4-Me)C6H2] do not react with the metal carbonyl dimers. An interesting feature of these new heterobimetallic complexes, 3a, 3b, and 5, is the existence of the thermal fragmentation process to regenerate the starting materials: 3a or 3b is actually in equilibrium with a mixture of 1 and 2a or 1 and 2b, respectively [ΔG298k0 = -4.1 ± 0.2 kcal mol-1 (3a), -4.3 ± 0.2 kcal mol-1 (3b)]. The Ti-Ru compound 5 thermally undergoes fragmentation to regenerate 1 and 4. The formation of these heterobimetallic complexes is formally considered as the metal-metal bond cleavage of metal carbonyl dimers by a Ti(III) reducing reagent; possible mechanisms are discussed.
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U2 - 10.1021/om020869l
DO - 10.1021/om020869l
M3 - Article
AN - SCOPUS:0037474784
SN - 0276-7333
VL - 22
SP - 1376
EP - 1382
JO - Organometallics
JF - Organometallics
IS - 7
ER -