Anomalous properties group 1 metals

Group IVA Donor Ligands. The anomalous reactions of PhaSiCl with metal carbonyl anions are discussed on p. 180. Only in the case of [Co(CO)3PPh3] was the normal substitution product obtained. GeH3Br reacts with Na-[Co(CO)4] in ether to produce [H3GeCo(CO)4]. The trideuterio-compound has also been prepared and spectroscopic properties reported for both compounds. The preparation and attempted preparation of halogen-bridged Ge-M compounds is referred to on pp. 180 and 200. In the case of cobalt. 

All group 2 elements are metals, but an abrupt change in properties between Be and Mg occurs as Be shows anomalous behavior in forming mainly covalent compounds. Beryllium most frequently displays a coordination number of four, usually tetrahedral, in which the radius of Be2+ is 27 pm. The chemical behavior of magnesium is intermediate between that of Be and the heavier elements, and it also has some tendency for covalent bond formation. 

In Section 11.3, we noted that the properties of Li and its compounds are often considered to be anomalous when compared with those of the later group 1 metals, and that a diagonal relationship exists between Li and Mg. In this section, we consider this relationship in detail and also describe a similar diagonal relationship between Be and Al. The positions of Li, Be, Mg and Al in the periodic table are shown in diagram 12.8. 

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