# Chemistry - Unusual oxidation numbers for alkaline earth metals?

## Solution 1:

This answer is an extension to @Ian Bush answer. Not only magnesium, but every group 2 element has a lower oxidation state of +0(beryllium) and +1(for other metals).

1. Be(0)

A 2016 paper gives an insight to the existence of a zero valent beryllium complex compound i.e it has been verified through computational method but it is yet to be synthesized.

[...]The team added a single ligand i.e CAAC = cyclic (alkyl)(amino)carbene to $$\ce{BeCl2}$$ in benzene solution to give $$\ce{(CAAC)BeCl2}$$, and obtained the final product, $$\ce{[Be(CAAC)2]}$$, by reducing the beryllium with KC8 in the presence of a second equivalent of CAAC ligand.

1. Be(I)

High resolution infrared emission spectra of beryllium monohydride and monodeuteride have been recorded. The molecules were generated in a furnace-discharge source, at 1500 °C and 333 mA discharge current, with beryllium metal and a mixture of helium and hydrogen or deuterium gases.(source)

1. Mg(I)

It has been described in @Ian Bush's answer. For more information, refer to these sources(1 and 2). Some examples are $$\ce{Mg2RuH4, Mg3RuH3, and Mg4IrH5}$$ having the $$\ce{Mg-Mg}$$ bond and magnesium diboride containing the metastable $$\ce{Mg2^{2+}}$$ ion(Credit @Oscar Lanzi).

1. Ca(I)

A Ca(I) Sandwich Complex $$\ce{[(thf)3Ca(μ-C6H3-1,3,5-Ph3)Ca(thf)3]}$$ is being described in this 2010 paper.

1. Sr(I)

The high-resolution infrared spectrum of gas-phase $$\ce{SrF}$$ was obtained in emission with a Fourier transform spectrometer.[...] (Source)

1. Ba(I)

3 isotopes of barium in $$\ce{BaF}$$ (Source). In [2018] Wu and Lerner (source) reported a barium(I) in a complex graphite intercalation compound.

I did not had to google each and every element to search for lower oxidation state. The wikipedia article of oxidation element gave a list of all posible O.S of element. Information regarding unusual O.S of any element can be found in the footnote and thus only clicked the relevant elements for the answer.

## Solution 2:

Magnesium(I) compounds are known, but they are of the form $$\ce{[Mg-Mg]^{2+}}$$ rather than a bare $$\ce{Mg+}$$ - so more like Mercury than Sodium. See https://pubs.rsc.org/en/content/articlelanding/2011/dt/c0dt01831g#!divAbstract, and in a way this furthers the similarity between Mg and Zn. Similar compounds are also possible for the heavier metals.