The versatile reactivity of cyclo-(P5tBu4)- with complexes of the nickel triad

Homoleptic mono-, di-, and tetra-iron complexes featuring phosphido ligands: a synthetic, structural, and spectroscopic study

We report the first series of homoleptic phosphido iron complexes synthesized by treating either the β-diketiminato complex [(Dippnacnac)FeCl₂Li(dme)₂] (Dippnacnac = HC[(CMe)N(C₆H₃-2,6-iPr₂)]₂) or [FeBr₂(thf)₂] with an excess of phosphides R₂PLi (R = tBu, tBuPh, Cy, iPr). Reaction outcomes depend strongly on the bulkiness of the phosphido ligands. The use of tBu₂PLi precursor led to an anionic diiron complex 1 encompassing a planar Fe₂P₂ core with two bridging and two terminal phosphido ligands. An analogous reaction employing less sterically demanding phosphides, tBuPhPLi and Cy₂PLi yielded diiron anionic complexes 2 and 3, respectively, featuring a short Fe-Fe interaction supported by three bridging phosphido groups and one additional terminal R₂P^- ligand at each iron center. Further tuning of the P-substrates bulkiness gave a neutral phosphido complex 4 possessing a tetrahedral Fe₄ cluster core held together by six bridging iPr₂P moieties. Moreover, we also describe the first homoleptic phosphanylphosphido iron complex 5, which features an iron center with low coordination provided by three tBu₂P-P(SiMe₃)^- ligands. The structures of compounds 1-5 were determined by single-crystal X-ray diffraction and 1-3 by ¹H NMR spectroscopy. Moreover, the electronic structures of 1-3 were interrogated using zero-field Mössbauer spectroscopy and DFT methods.

Group 6 metal carbonyl complexes of cyclo-(P5Ph5)

Group 6 metal (Cr, Mo, W) carbonyl complexes react with cyclo-(P5Ph5) to afford the phosphorus-rich complexes [Cr(CO)5{cyclo-(P5Ph5)-κP 1}] (1), [{Cr(CO)5}2{μ-cyclo-(P5Ph5)-κP 1,P 3}] (2), [M(CO)4{cyclo-(P5Ph5)-κP 1,P 3}] (with M=Cr (3), Mo (4), W (exo-5, endo -5)) depending on the reaction conditions. Complexes 1–5 were characterised by 31P{1H} NMR and IR spectroscopy, elemental analysis, and X-ray crystallography. The cyclopentaphosphane remains intact and acts as monodentate (1), bridging (2) or bidentate (3–5) ligand. Compounds exo-5 and endo -5 are configurational isomers and essentially differ in the orientations adopted by the phenyl rings attached to the uncoordinated phosphorus atoms. The 31P{1H} NMR spectra show five multiplets for an ABCDE spin system. Theoretical calculations showed that exo-5 and endo-5 are practically isoenergetic, which is in good agreement with the observed equilibrium in solution between exo-5 and endo-5. The thermal properties of the complexes have also been evaluated.

The new diphosphanylphosphido complexes of tungsten(vi) and molybdenum(vi). Their synthesis, structures and properties

We report on the reactivity of R2P-P(Li)-PR'2 (R = tBu, iPr, R' = NEt2, iPr) towards diimido complexes [(dippN)2MCl2·dme] (M = Mo, W and dipp = 2,6-iPr2C6H3). A series of new complexes with diphosphanylphosphido ligands R2P-P-PR'2 were isolated. The solid-state structures of [(dippN)2M(Cl)(1,2-η-iPr2P-P-PiPr2)] (2Mo and 2W) and [(dippN)2M(Cl){1,2-η-tBu2P-P-P(NEt2)2}] (3Mo and 3W) were established by single-crystal X-ray diffraction analysis and indicate a side-on geometry of the R2P-P-PR'2 moiety. 3W and 3Mo are the first triphosphorus complexes with the amido ligand NEt2 on the P atom. [(dippN)2M(Cl)(1,2-η-tBu2P-P-PtBu2)] (1Mo and 1W) and 3Mo and 3W display similar side-on geometry in solution and in the solid state. By contrast, 2Mo and 2W reveal a dynamic behavior in solution. For the first time, the reactivity of diphosphanylphosphido complexes towards different nucleophiles was studied. The complexes react with the phosphorus nucleophile Ph2PLi, yielding phosphanylphosphinidene complexes [(dippN)2M(Cl)(η2-P-PR2)]- Li+ (M = Mo, W) together with related diphosphanes R'2P-PPh2. Carbon nucleophile MeLi does not yield [(dippN)2M(Cl)(η2-P-PR2)]- Li+ but substitutes a Cl ligand at the metal center. Moreover, we compare the coordination of the R2P-P-PR'2 moiety to different metal centers based on DFT methods.

Platinum(II) tetramesityltetraphosphane-1,4-diides

[Na(2)(thf)(4)(P(4)Mes(4))] () (Mes = 2,4,6-Me(3)C(6)H(2)) reacts with one equivalent of [PtCl(2)(cod)] (cod = 1,5-cycloctadiene) or [PtCl(2)(dppe)] (dppe = bis(diphenylphosphino)ethane) to give the corresponding platinum(II) tetramesityltetraphosphane-1,4-diide complexes [Pt(P(4)Mes(4))(cod)] () and [Pt(P(4)Mes(4))(dppe)] (). The Pt-P bonds of these complexes proved to be extraordinarily stable and did not react with insertion reagents such as tert-butyl isocyanide or cyclohexyl isocyanide. Instead, ligand transfer occurred to give [Pt(P(4)Mes(4))(C[triple bond, length as m-dash]NBu(t))(2)] () and [Pt(P(4)Mes(4))(C[triple bond, length as m-dash]NCy)(2)] (). Further reactions of with CO, CS(2), white phosphorus, MeI and ethyl diazoacetate led either to formation of cyclo-P(4)Mes(4) and cyclo-P(3)Mes(3) or to unidentified products, in which no evidence of insertion of these reagents into the Pt-P bond was observed.

Different transmetallation behaviour of [M(P4HR4)] salts toward rhodium(I) and copper(I) (M = Na, K; R = Ph, Mes; Mes = 2,4,6-Me3C6H2)

[K(2)(P(4)Mes(4))] (1) or [Na(2)(THF)(4)(P(4)Mes(4))] (2) (Mes = 2,4,6-Me(3)C(6)H(2)) reacts with one equivalent of HCl and subsequently with 0.5 equivalents of [{RhCl(cod)}(2)] (cod = 1,5-cyclooctadiene) to give a mixture of rhodium complexes, from which [Rh(P(4)HMes(4))(cod)] (3) and the secondary product [Rh(2)(micro-P(2)HMes(2))(mu-PHMes)(cod)(2)] (4) were isolated and characterised by X-ray diffraction studies. Alternatively, the reaction of [K(2)(P(4)Ph(4))] (5) or [Na(2)(THF)(5)(P(4)Ph(4))] (6) with one equivalent of HCl and subsequently with one equivalent of [CuCl(PCyp(3))(2)] (Cyp = cyclo-C(5)H(9)) gave the complex [Cu(4)(P(4)Ph(4))(2)(PH(2)Ph)(2)(PCyp(3))(2)] (7), presumably via disproportionation of the monoanion (P(4)HPh(4))(-).