Novel Synthesis, X-ray Crystal Structures, and Spectroscopic Properties of Metalated Hypervalent Phosphorus Compounds, Cp(CO)LFe{P(OC₆H₄Y)(OC₆H₄Z)} (L = CO, P(OPh)₃, P(OMe)₃, PMe₃; Y, Z = NH, NMe, O)

Abstract

Iron phosphorane complexes, (1a, Y = NH; 1b, Y = NMe; 3, Y = O), have been prepared from [Cp(CO)2Fe{P(OPh)3}]PF6, o-HOC6H4YH, and a Lewis base. (2a, R = H; 2b, R = Me) having two different chelates on the phosphorus has been prepared from o-HOC6H4NRH, and a Lewis base. These reactions involve nucleophilic attacks of an organic nucleophile at a trivalent phosphorus coordinated to an iron and substitution on the phosphorus. During the course of preparation of 1b, (4) was isolated, which corresponds to one of the intermediates on the reaction pathways to give 1−3. 4 reacts with a Lewis base to give 1b. The reaction of hydridophosphorane with n-BuLi leads to NH proton abstraction to give the amide which then reacts with Cp(CO)LFeCl to yield (5, L = P(OPh)3; 6, L = P(OMe)3; 7, L = PMe3) by an apparent 1,2-proton migration. The X-ray structures of 1b, 2b, and 4 were determined. 1b and 2b have slightly distorted trigonal-bipyramidal geometries around the phosphorus with the iron fragment in the equatorial position and have P−Oeq bonds longer than those of organophosphoranes, indicating that the Cp(CO)2Fe fragment serves as a strong π donor. The Fe−P(phosphorane) bond rotates freely in solution even at −50 °C. A Berry pseudorotation around the phosphorane phosphorus does not occur for 1a,b, 2a,b, and 5−7, whereas it does for 3.

A Nontrigonal Tricoordinate Phosphorus Ligand Exhibiting Reversible “Nonspectator” L/X‐Switching

“…Verkade has postulated that fluoride addition to Pd II ‐(bis)phosphines induces Pd II →Pd 0 reduction via initial addition of F − to P . Further, Nakazawa and Miyoshi have shown the possibility of nucleophilic substitution of P‐substituents in cationic Fe II ‐phosphite complexes, in some cases leading to persistent (σ 4 ‐P)–M products …”

“…Thea bility for nontrigonal s 3 -P ligands to reversibly expand local coordination number while remaining s-bound in the primary ligand sphere of ametal complex forecasts emerging opportunities for functional nonspectator ligands within (s 3 -P)-M complexes. [22] On the basis of precedent from Martin [23] and Nakazawa and Miyoshi, [18,19] the cyclopentadienyliron dicarbonyl cation (Fp + )w as selected as ac oordinatively saturated "ancillary metal" [24] fragment for study.I ron complexes 1a•Fp + and 1b•Fp + were prepared by ligand exchange of [thf•Fp][PF 6 ] [25] with P{N[o-NMe-C 6 H 4 ] 2 }(1a) [26,27] and (Me 2 N) 3 P(1b), respectively ( Figure 2).…”

121Sb Mössbauer Spectra of Hypervalent Complexes Having an Antimony-transition Metal Bond and Partial Quadrupole Coupling Constants

“…The X-ray determinations for the metal ligand compounds [10 -14] support the -donation mechanism; The apical Sb-O lengths of these compounds are longer, and the apical O-Sb-O angles are smaller, than those of Rf 2 SbTol [21], indicating that the metal fragments are electron-donating. It is noteworthy that the -back donation of the metal fragment into the axial antibonding MO of Sb, which is found in the hypervalent phosphoranes with the iron fragment [22], is not important because suchback donation should cause a decrease in the 2 value. The values, showing the electron density at the Sb nucleus, reflect the Sb 5s electron density directly and the Sb 5p density indirectly through the shielding effect of the p electrons.…”

A Nontrigonal Tricoordinate Phosphorus Ligand Exhibiting Reversible “Nonspectator” L/X‐Switching

“…On the basis of precedent from Martin 23 and Nakazawa and Miyoshi, 18,19 the cyclopentadienyliron dicarbonyl cation (Fp + ) was selected as a coordinatively saturated 'ancillary metal' 24 26,27 and (Me2N)3P (1b), respectively ( Figure 2). According to IR spectroscopy, the CO stretching frequencies of 1a•Fp + (νasym 2017 cm -1 , νsym 2061 cm -1 ) are higher in energy than those of 1b•Fp + (νasym 2000 cm -1 , νsym 2045 cm -1 ).…”