# Tag Info

12

We sometimes call this type of complex 'pseudotetrahedral' since there is an isomerism from a tetrahedral to a square planar complex possible. I was unable to find the original work here but this link gives some information. As you already mentioned there are two strong and two weak ligands so it's hard to tell how strong the ligand field splitting will be. ...

9

Dichlorobis(triphenylphosphine)nickel(II), or $\ce{NiCl2[P(C6H5)3]2}$ in square planar form is red and diamagnetic. The blue form is paramagnetic and features tetrahedral Ni(II) centers. Both tetrahedral and square planar isomers coexist in solutions. Weak field ligands, favor tetrahedral geometry and strong field ligands favor the square planar isomer. Both ...

6

It is postulated that the trifluroborates are not the transmetallating specis, rather than to be the source of slow hydrolysis to yield boronic acids: (source, slide 41; citing Molander and Biolatto, B. in J. Org. Chem., 2003, 68, 4302-4314) which then enter the catalytic cycle: (preview in Kurti / Czako, page 448 bottom) Organic Reactions (vide infra) ...

6

It’s not really a dichotomy, it’s just two very different reaction mechanisms. For the cuprate addition, which also applies to general Grignard-type additions, in principle the reaction is reversible (figure 1). Figure 1: Reversibility of Michael additions. However, the reverse direction is only really possible if the anion released is somewhat stable. In ...

5

To quote Hartwig: Oxidative addition to more electron-rich metal centres tends to be more favourable than oxidative addition at metal poor centres [1] This is generally a thermodynamic issue, and can be rationalised quite easily if one considers that the change in electron density at the metal centre during the oxidative addition process (note, theres a ...

5

You don't have to wonder about which alkene coordinates to the Pd(II) centre. In this case, they are conjugated and therefore can coordinate together as a diene, which is a 4-electron donor. Many pi complexes are known ranging from alkenes (2e donor), to allyl (3e), to diene (4e), to cyclopentadienyl (5e), ... so this is not something really surprising. ...

4

The bite angle of a bidentate ligand often has a pronounced effect on reactivity, but it can be difficult to predict a priori whether a given reaction will be enhanced by increasing or decreasing bite angle - you can see this if you ever read a paper where new ligands / catalysts have been developed, which are often accompanied with large tables of screening ...

1

Alkenes are very capable of a similar carbometallation reaction as you can see in the scheme below (ref: R. M. Sultanov et al. / Tetrahedron Letters 54 (2013) 6619–6623): I think the reasons why such reaction with alkenes is not so common is: It is useless (correct me if i am wrong). Hence the reason why the work in the scheme above was published in a low ...

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