The four-coordinate scandium phosphinidene complex, [LSc(μ-PAr)]2 (L = (MeC(NDIPP)CHC(Me)(NCH2CH2N((i)Pr)2)), DIPP = 2,6-((i)Pr)2C6H3; Ar = 2,6-Me2C6H3) (1), has been synthesized in good yield, and its reactivity has been investigated. Although 1 has a bis(μ-phosphinidene)discandium structural unit, this coordinatively unsaturated complex shows high and versatile reactivity toward a variety of substrates. First, two-electron reduction occurs when substrates as 2,2'-bipyridine, elemental selenium, elemental tellurium, Me3P═S, or Ph3P═E (E = S, Se) is used, resulting in the oxidative coupling of two phosphinidene ligands 2[PAr](2-) into a diphosphene ligand [ArP-PAr](2-). Complex 1 easily undergoes nucleophilic addition reactions with unsaturated substrates, such as benzylallene, benzonitrile, tert-butyl isocyanide, and CS2. This complex also shows a peculiar reactivity to CO and Mo(CO)6, that includes C-P bond formation, C-C coupling and C-O bond cleavage of CO, to afford novel phosphorus-containing products. In the last two types of reactivity, reaction profiles have been computed (for the insertion of (t)BuNC and the CO activation by 1) at the DFT level. The unexpected/surprising sequence of steps in the latter case is also revealed.

A rare find: Soluble P3−‐containing rare‐earth‐metal coordination compounds have been synthesized. A P3−‐containing polymetallic yttrium iodide was obtained through PSi (or H) and PC bond cleavage, and this compound can be transferred into other P3−‐containing yttrium coordination compounds by metathesis reactions.

Rare-earth metal phosphido methyl complexes [LLn(Me){P(H)Ar}] react with triphenylphosphine oxide to give [LLn(Ph){CH2P(O)Ph2}], indicating C(alkyl)–P bond formation and C(aryl)–P bond cleavage.