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, ⁿPr, ⁿBu), Ph₂P(O)CH(OH)ⁿPr, and cis-[MoO₂Cl₂{(Ph₂P(O)CH₂)₂NEt-κO,κO}]

Abstract

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 Ph(2)P(O)CH(2)N(R)CH(2)P(O)Ph(2) (R = Me, (n)Pr, (n)Bu). Aminobis(phosphines) also undergo methylene insertion when treated with paraformaldehyde to give bis(phosphine oxides) Ph(2)P(O)CH(2)N(R)CH(2)P(O)Ph(2) (R = Me, Et, (n)()Pr, (i)()Pr, (n)Bu) in good yield. The reaction of aminophosphines with aromatic aldehydes ArCHO leads to insertion of "ArCH" into the P-N bond to give Ph(2)P(O)CH(R)N(H)Ph (R = C(6)H(5), furfuryl, o-C(6)H(4)OH), but with aliphatic aldehydes such as butanal, P-N bond cleavage takes place to afford alpha-hydroxy phosphine oxide. The reaction of aminobis(phosphines) with both aromatic and aliphatic aldehydes leads to the formation of alpha-hydroxy phosphine oxides through P-N bond cleavage whereas the reaction with furfural leads to the P-N bond insertion. The structure of the alpha-hydroxy derivative Ph(2)P(O)CR(H)(OH)(n)()Pr 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-[MoO(2)Cl(2)((OPPh(2)CH(2))(2)NEt-kappaO,kappaO)], shows the distorted octahedral geometry around Mo with two oxo groups cis to each other.

Crystal structure of (diphenylphosphinoyl)phenylmethanol, C19H17O2P

“…These show typical aromatic character. The distance of P1O1 (1.494 Å) is very close to P=O bond length (1.493 Å) reported in the literature [3]. There are no intermolecular p-p stacking interactions in the crystal structure.…”

N-Benzyl and N-aryl bis(phospha-Mannich adducts): Synthesis and catalytic activity of the related bidentate chelate platinum complexes in hydroformylation

“…The use of phosphorous acid as the P-reactant led to bis(phosphonic acids) [16,17]. Bis(phosphinoxido)derivatives were synthesized via a surprising methylene insertion reaction into a PeN bond followed by oxidation [18].…”

Cyclodiphosphazanes with functionalities: Synthesis, reactivity and transition metal chemistry

“…Previously, we suggested a mechanism for the methylene insertion into the P-N bonds in aminophosphines involving a Staudinger-Wittig pathway, in which (c) proton transfer occurs from nitrogen to the phosphorus center to give R 2 P(O)H as an intermediate [28]. However, this mechanism fails to explain the insertion observed in non-proton containing aminophosphines such as RN(PPh 2 ) 2 and Ph 2 PN(C 2 H 4 ) 2 PPh 2 , hence it was concluded that the presence of the NH group is not a requirement [29,30]. The reactivity of cis-[{P(l-N t Bu)N(H) t Bu} 2 ] towards paraformaldehyde indicates that the preferential exocyclic P-N bond insertion is essentially due to the relatively more basic nature of the amide nitrogens compared to the ring nitrogen atoms.…”