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12

This is by no means a trivial case. You are dealing with a so-called template or interstitial atom placement within a cluster shell. There is a thorough review available [1, pp. 18–20] (reference numbers updated): An alternative way of satisfying the closed shell electronic requirements and retaining a positive charge on the cluster is possible if an ...


9

To quote from the comments: you can get things into an amazing variety of oxidation state given the right environment. In the case of maximal oxidation states, particularly above $+2$ or $+3$ in the $3d$ transition series, the right environment (at least in simple species) involves complexation with ligands that are highly electronegative, capable of ...


7

It is a good question, it is a gemstone hiding in the mud. I have searched the Cambridge database, all the bis-acetylacetonatonickel complexes which have four coordinate nickel centres are square planar. There are three common coordination geometries for nickel(II) which we need to consider. Tetrahedral, square plannar and octahedral. Here is a diagram (...


5

Since the equilibrium constant for the formation of the complex ion is very large, I assume that $\ce{[Ni(CN)4^{2-}] >> [Ni^{2+}]}$ From the comments: [comments:] That assumption is incorrect. The equilibrium constant seems large, but the exponents are high, so it is misleading. In fact, more of the cyanide is in the form of HCN than in complex ...


5

For organometallic complexes it's often easier to throw the "more electronegative element" idea out entirely and focus on the characteristics of the ligands. This is what @andselisk's comment is referring to. Generally ligands are partitioned into two types, $\ce{L}$ and $\ce{X}$: $\ce{L}$ refers to neutral ligands: for example $\ce{CO}$, phosphines, $\ce{...


3

There are several things which are needed to be known to be able to deal with this question. Firstly there is the 18 Valence Electron (18VE) rule (description at libretexts.org). The iron pentacarbonyl is an 18VE complex. It is coordinatively saturated. A low valent transition metal complex with strong ligand field ligands is considered to be coordinatively ...


3

This seems to be the case of "show, don't tell". IUPAC's definition of coordination number (C.N.) which applies to inorganic complexes: In an inorganic coordination entity, the number of σ-bonds between ligands and the central atom. π-bonds are not considered in determining the coordination number. Let's have a look at the one of the first determined ...


2

As Ivan Neretin told it, each group oxalate has two groups $\ce{-COO^-}$. So it may be bound to a central metal by two oxygen atoms, one per group $\ce{-COO^-}$.


2

There is no simple way to predict beforehand as far as I know. This is a general knowledge type of chemistry question, you will have to know or memorize the colors of common anions and cations. It will be much easier, if you do so group wise and know the colors of the first row of transition element ions. Any object which absorbs a certain portion of ...


2

There is a very similar molecule in the literature this has aryls instead of methyls. (MEYTEP) M.A.C.Lacabra, A.J.Canty, M.Lutz, J.Patel, A.L.Spek, Huailin Sun, G.van Koten, Inorg.Chim.Acta, 2002, volume 327, page 15. In the Cambridge database this compound is considered as a Pt(II) compound in the paper. We also have the dimethyl compound with bridging ...


2

Both complexes (and many more such as permanganate, sulphate, …) share the same general MO scheme which I am going to shamelessly copy from my older answer: Figure 1: Qualitative MO scheme of a tetrahedric complex with σ and π bonding between metal and ligands. Double vertical lines represent electron pairs. The intense colour of permanganate ...


1

Cyano- is related to the neutral CN group. Cyanido- is related to the CN- anion. Cyanato- is related to the CNO- anion.


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