Photochemical isomerization of metal ethene to metal vinyl hydride complexes: a matrix-isolation and solution NMR study

Preparation and synthetic applications of alkene complexes of group 9 transition metals in [2+2+2] cycloaddition reactions

“…37 Common routes to the corresponding Ir(I)-complexes are complementary to the routes for Rh(I)-complexes (Scheme 14). 38 As mentioned above the common starting material for the preparation of the chlorido-bridged dimeric COD complex 20 is IrCl 3 ÁxH 2 O. Subsequent anion exchange gives the bis-COD complex 21.…”

“…A detailed study on asymmetric cross-cyclotrimerisation reactions was reported by us recently. 51 The use of the planar chiral [(1-neomenthylindenyl)Co(COD)] complex (11) at low temperature under photochemical conditions was the key to accessing a range of enantiomerically pure biaryls (39) from diynes (38) and nitriles (Scheme 21). The reaction was tolerant to a large range of differently functionalised nitriles, giving the biaryls (39) with acceptable to very good yields and also selectivities of up to 94% ee.…”

The Photochemistry of the (Cycloalkene)(hydro)(trispyrazolylborato)iridium Complexes [Ir(η4-cod)(TpMe2)] and [Ir(η2-coe)H2(TpMe2)]: the Formation of [IrH4(TpMe2)] and [Ir(CO)H2(TpMe2)]

“…Therefore, one of the CÀH bonds of the CH 2 groups of the dialkene could get sufficiently close to the metal atom, displace the coordinated solvent and enter into an agostic interaction with the metal center (15). This interaction could then induce the oxidative addition of this CÀH bond with formation of the hydrido h (17) and that the latter, as proposed for 1, under photochemical conditions, will form {IrH 2 (Tp Me2 )} (2) with liberation of the cycloocta-1,3,5-triene detected in the mass spectrum of the solution at the end of the photolysis. By analogy with the related reactions described above, it is proposed that {IrH 2 (Tp Me2 )} (2) will further react with CH 3 OH as depicted in Scheme 4.…”

Photo-isomerisation of alkenyl complexes of platinum(ii): structural, spectroscopic, kinetic and computational investigations

“…1 With reference to species having the metal directly bound to a vinyl carbon (also called metal-vinyl compounds), they are generally obtained as a result of: (i) nucleophilic addition to a coordinated alkyne or a metal vinylidene complex, 2,3 (ii) insertion of an alkyne, or sometimes an allene, into a metal-hydrogen, [4][5][6][7][8][9][10] metal-carbon, 11,12 or even metalsulphur bond, 13 (iii) oxidative addition to low valent metal species. [14][15][16][17] In the formation of metal alkenyl complexes, the presence of substituents on the unsaturated carbons can lead to different isomers whose yield depends upon their kinetic preference and subsequent possible isomerisation process. 2,6,8,11 An interesting example of how the regio-selectivity can be governed by steric effects has been reported.…”