Insertion of Carbon Fragments into P(III)−N Bonds in Aminophosphines and Aminobis(phosphines): Synthesis, Reactivity, and Coordination Chemistry of Resulting Phosphine Oxide Derivatives. Crystal and Molecular Structures of (Ph₂P(O)CH₂)₂NR (R = Me, <i>ⁿ</i>Pr, <i>ⁿ</i>Bu), Ph₂P(O)CH(OH)<i>ⁿ</i>Pr, and <i>cis</i>-[MoO₂Cl₂{(Ph₂P(O)CH₂)₂NEt-κ<i>O</i>,κ<i>O</i>}]

Reactions of N-aryl and N-alicyclic derivatives of aminophosphines with paraformaldehyde lead to methylene insertion into P−N bond followed by oxidation of phosphorus from the P(III) to P(V) state. When N-alkyl derivatives are reacted with paraformaldehyde, dimerization takes place to afford bis(phosphine oxide)s of the type Ph2P(O)CH2N(R)CH2P(O)Ph2 (R = Me, nPr, nBu). Aminobis(phosphines) also undergo methylene insertion when treated with paraformaldehyde to give bis(phosphine oxides) Ph2P(O)CH2N(R)CH2P(O)Ph2 (R = Me, Et, nPr, iPr, nBu) in good yield. The reaction of aminophosphines with aromatic aldehydes ArCHO leads to insertion of “ArCH” into the P−N bond to give Ph2P(O)CH(R)N(H)Ph (R = C6H5, furfuryl, o-C6H4OH), but with aliphatic aldehydes such as butanal, P−N bond cleavage takes place to afford α-hydroxy phosphine oxide. The reaction of aminobis(phosphines) with both aromatic and aliphatic aldehydes leads to the formation of α-hydroxy phosphine oxides through P−N bond cleavage whereas the reaction with furfural leads to the P−N bond insertion. The structure of the α-hydroxy derivative Ph2P(O)CR(H)(OH)nPr shows intermolecular hydrogen bonding between OH and PO oxygen. The phosphine oxide derivatives act as bidentate ligands and form chelate complexes with Co(II), Mo(VI), Th(IV), and U(VI) derivatives. The crystal structure of the molybdenum complex, cis-[MoO2Cl2{(OPPh2CH2)2NEt-κO,κO}], shows the distorted octahedral geometry around Mo with two oxo groups cis to each other.