Mono- and di-nickellaazaphosphiranes of mono- and bis-(amido)cyclodiphosph(III)azanes

Cyclodiphosphazanes: options are endless

This short review describes the transition metal chemistry of cyclodiphosphazanes.

Chemistry of pnictogen(iii)–nitrogen ring systems

This critical review covers significant recent advances in the chemistry of pnictogen(III)-nitrogen ring systems, also known as cyclopnict(III)azanes. The synthetic methodologies and reactions of the heavier pnictogen systems are compared with the well-developed chemistry of cyclophosph(III)azanes. Particular attention is focused on ring-oligomerization processes and the use of four-membered E(2)N(2) rings as building blocks for the synthesis of macrocyclic molecules. Main-group element and transition-metal complexes are also discussed (95 references).

Bis(1°-amino)cyclodistib(III)azanes: the First Structural Characterization of cis and trans Isomers of a Single Cyclodipnict(III)azane

The dichlorocyclodistib(III)azane [ClSb(mu-NtBu)]2 (1) has been shown to exist as the cis isomer in the solid state. A series of bis(1 degree-amino)cyclodistib(III)azanes [R'NHSb(mu-NtBu)]2 (2, R' = tBu; 3, R' = Dipp; 4, R' = Dmp) has been prepared by the reaction of 1 with 2 equiv. of LiNHR'. On the basis of NMR solution spectra, all three derivatives are formed as a mixture of cis and trans isomers. In the case of 3, the structures of both the cis and trans isomers have been determined by X-ray crystallography; cis-3 adopts an endo, endo arrangement for the amido protons of the DippNH groups. Isomerization of trans-3 into cis-3 occurs slowly in solution. Deprotonation of 2 with 2 equiv. of nBuNa or trans-3 with nBuLi produces [Na2Sb2(mu-NtBu)4] (5) and [Li2Sb2(mu-NtBu)2(mu-NDipp)2] (6), whose solvated cubane structures were established by X-ray crystallography. In contrast, the reaction of cis-3 with 2 equiv. of nBuLi produces the tricyclic compound [Li2Sb(mu-NtBu)2(mu-NDipp)(mu-NHDipp)] (7).

Zinc complexes of anionic NPPN and NP(S)PN ligands and rearrangement to the isomeric NPNP and NP(S)NP ligands in mercury complexes

The lithium (imido)diphosphineimide Li(Et2O)[DippNPhP-P((n)Bu)PhNDipp] (1) (Dipp = 2,6-(i)Pr2C6H3) undergoes simple metathesis reactions with equimolar amounts of zinc halides, ZnCl2 and (t)BuZnBr, to give the respective N,N'-chelated complexes {Zn(micro-Cl)[DippNPhP-P((n)Bu)PhNDipp]}2 (2) and (t)BuZn[NDippPhP-P((n)Bu)PhNDipp] (3). In contrast, the reaction of two equivalents of complex 1 with HgCl2 affords the rearranged bis(imidodiphosphinoamine) complex, Hg[PhP([double bond, length as m-dash]NDipp)(micro-NDipp)P((n)Bu)Ph]2 (4), where the ligand acts as a P-centered anion. The (imido)diphosphineimide backbone of remains intact on oxidation with elemental sulfur to afford the lithium (imido)diphosphineimine sulfide complex, Li(Et2O)[DippNPhP(S)-P((n)Bu)PhNDipp] (6). Reactions of 6 with group 12 metal halides show similar behaviour to those of complex 1. The N,N' chelated metathesis products RZn[DippNPhP(S)-P((n)Bu)PhNDipp] (7, R = Cl; 8, R = (t)Bu) are obtained on reaction with ZnCl2 and (t)BuZnBr, respectively. Isomerization of the ligand backbone occurs on reaction of 6 with HgCl2 to form the homoleptic P,S-chelated mercury complex Hg[Ph(S)P(=NDipp)(micro-NDipp)P((n)Bu)Ph]2 (9). Complexes 2, 3, 4, 6, 8 and 9 have been characterized by X-ray crystallography.

Reversal of polarization in amidophosphines: neutral- and anionic-kappaP coordination vs. anionic-kappaP,N coordination and the formation of nickelaazaphosphiranes

Nickel(ii) chloride reacts with the bis(tert-butylamino)diazadiphosphetidine {Bu(t)(H)NP(micro-NBu(t))(2)PN(H)Bu(t)} to form trans-[{Bu(t)(H)NP(micro-NBu(t))(2)PN(H)Bu(t)}(2)NiCl(2)]. In solution and the solid-state each heterocyclic ligand coordinates nickel through one phosphorus atom only. For comparison the solid-state structure of the known trans-[NiCl(2)(PEt(3))(2)] was also determined and it was found that the two complexes have almost identical bond parameters about nickel. The nickel-amidophosphine complexes [{Bu(t)OP(micro-NBu(t))(2)PNBu(t)}NiCl(PBu(n)(3))], [(PBu(n)(3))ClNi{Bu(t)NP(micro-NBu(t))(2)PNBu(t)}NiCl(PBu(n)(3))], and [{Me(2)Si(micro-NBu(t))(2)PNBu(t)}NiCl(PBu(n)(3))] were synthesized and X-ray structurally characterized. In these mono- and di-nuclear nickel complexes the nickel ions are coordinated in pseudo square-planar fashions, by one trialkylphosphine ligand, one chloride ligand and one kappaP,N-coordinated amidophosphine moiety from tert-butylamido-substituted heterocycles. Attempts to create nickel complexes chelated in a kappa(2)P fashion by the o-phenylenediamine-tethered mono- and di-anionic 1-{Me(2)Si(micro-NBu(t))(2)PN} 2-{Me(2)Si(micro-NBu(t))(2)PNH}C(6)H(4) and 1,2-{Me(2)Si(micro-NBu(t))(2)PN}C(6)H(4), respectively, afforded instead [1,2-{Me(2)Si(micro-NBu(t))(2)PN}{Me(2)Si(micro-NBu(t))(2)PN}C(6)H(4)NiCl] and [1,2-{Me(2)Si(micro-NBu(t))(2)PN}{Me(2)Si(micro-NBu(t))(2)PN}C(6)H(4)Ni{PEt(3)}], each complex having kappaP,N and kappaP coordinated amidophosphine ligands.

Cyclodiphosphazanes with Hemilabile Ponytails: Synthesis, Transition Metal Chemistry (Ru(II), Rh(I), Pd(II), Pt(II)), and Crystal and Molecular Structures of Mononuclear (Pd(II), Rh(I)) and Bi- and Tetranuclear Rhodium(I) Complexes

Cyclodiphosphazanes having hemilabile ponytails such as cis-[(t)()BuNP(OC(6)H(4)OMe-o)](2) (2), cis-[(t)()BuNP(OCH(2)CH(2)OMe)](2) (3), cis-[(t)BuNP(OCH(2)CH(2)SMe)](2) (4), and cis-[(t)BuNP(OCH(2)CH(2)NMe(2))](2) (5) were synthesized by reacting cis-[(t)()BuNPCl](2) (1) with corresponding nucleophiles. The reaction of 2 with [M(COD)Cl(2)] afforded cis-[MCl(2)(2)(2)] derivatives (M = Pd (6), Pt (7)), whereas, with [Pd(NCPh)(2)Cl(2)], trans-[MCl(2)(2)(2)] (8) was obtained. The reaction of 2 with [Pd(PEt(3))Cl(2)](2), [{Ru(eta(6)-p-cymene)Cl(2)](2), and [M(COD)Cl](2) (M = Rh, Ir) afforded mononuclear complexes of Pd(II) (9), Ru(II) (11), Rh(I) (12), and Ir(I) (13) irrespective of the stoichiometry of the reactants and the reaction condition. In the above complexes the cyclodiphosphazane acts as a monodentate ligand. The reaction of 2 with [PdCl(eta(3)-C(3)H(5))](2) afforded binuclear complex [(PdCl(eta(3)-C(3)H(5)))(2){((t)BuNP(OC(6)H(4)OMe-o))(2)-kappaP}] (10). The reaction of ligand 3 with [Rh(CO)(2)Cl](2) in 1:1 ratio in CH(3)CN under reflux condition afforded tetranuclear rhodium(I) metallamacrocycle (14), whereas the ligands 4 and 5 afforded bischelated binuclear complexes 15 and 16, respectively. The crystal structures of 8, 9, 12, 14, and 16 are reported.

Non-stoichiometry induced by differential oxygen/lone pair occupation in chiral bicyclic 1,1′-binaphthoxy cyclodiphosphazanes

Non-stoichiometry and isostructurality in a set of chiral phosphorus compounds as a result of lone pair/oxygen exchange, substantiated by the combined use of 31P NMR spectroscopy and X-ray crystallography, is described.

Lithiation of (tBuNH)3PNSiMe3 and Formation of Tetraimidophosphate Complexes Containing M3O3 Rings (M = Li, K): X-ray Structure of the Stable Radical {(Me3SiN)P(μ3-NtBu)3[μ3-Li(THF)]3(OtBu)}

The reaction of ((t)BuNH)(3)PNSiMe(3) (1) with 1 equiv of (n)BuLi results in the formation of Li[P(NH(t)Bu)(2)(N(t)Bu)(NSiMe(3))] (2); treatment of 2 with a second equivalent of (n)BuLi produces the dilithium salt Li(2)[P(NH(t)Bu)(N(t)Bu)(2)(NSiMe(3))] (3). Similarly, the reaction of 1 and (n)BuLi in a 1:3 stoichiometry produces the trilithiated species Li(3)[P(N(t)Bu)(3)(NSiMe(3))] (4). These three complexes represent imido analogues of dihydrogen phosphate [H(2)PO(4)](-), hydrogen phosphate [HPO(4)](2)(-), and orthophosphate [PO(4)](3)(-), respectively. Reaction of 4 with alkali metal alkoxides MOR (M = Li, R = SiMe(3); M = K, R = (t)Bu) generates the imido-alkoxy complexes [Li(3)[P(N(t)Bu)(3)(NSiMe(3))](MOR)(3)] (8, M = Li; 9, M = K). These compounds were characterized by multinuclear ((1)H, (7)Li, (13)C, and (31)P) NMR spectroscopy and, in the cases of 2, 8, and 9.3THF, by X-ray crystallography. In the solid state, 2 exists as a dimer with Li-N contacts serving to link the two Li[P(NH(t)Bu)(2)(N(t)Bu)(NSiMe(3))] units. The monomeric compounds 8 and 9.3THF consist of a rare M(3)O(3) ring coordinated to the (LiN)(3) unit of 4. The unexpected formation of the stable radical [(Me(3)SiN)P(mu(3)-N(t)Bu)(3)[mu(3)-Li(THF)](3)(O(t)Bu)] (10) is also reported. X-ray crystallography indicated that 10 has a distorted cubic structure consisting of the radical dianion [P(N(t)Bu)(3)(NSiMe(3))](.2)(-), two lithium cations, and a molecule of LiO(t)Bu in the solid state. In dilute THF solution, the cube is disrupted to give the radical monoanion [(Me(3)SiN)((t)BuN)P(mu-N(t)Bu)(2)Li(THF)(2)](.-), which was identified by EPR spectroscopy.

Syntheses and X-ray structures of potassium derivatives and a paramagnetic nickel(II) complex of a cyclodiphosph(III/V)azane monoselenide

The cyclodiphosph(III/V)azane monoselenide [(t)Bu(H)N(Se)P(micro-N(t)Bu)(2)PN(H)(t)Bu] (6, H(2)cdppSe where cdpp = cyclodiphosphazane) is obtained in quantitative yield from the comproportionation reaction of equimolar amounts of H(2)cdpp (7) and H(2)cdppSe(2) (3) in toluene at 85 degrees C. The X-ray structures of 3 and 6 reveal that both the monoselenide and the diselenide adopt a cis,endo,exo arrangement of the (t)BuNH groups. Metalation of 6 with 1 equiv of KO(t)Bu or 2 equiv of KCH(2)Ph in THF produces [(THF)K[HcdppSe]](2) (8) or [[(THF)(2)K](2)[cdppSe]](2) (9), respectively. The initial deprotonation involves the (t)BuNH group attached to the P(V) center in 6. In the dimeric structure of 8, both of the monoanionic ligands are bis-N,Se-chelated to the two K(+) cations to give a distorted K(2)N(2)Se(2) octahedron. In the centrosymmetric dimer 9, the dianionic ligands adopt two different coordination modes to the bis-solvated K(+) ions, viz., tridentate N,N',N" coordination and N,Se-chelation involving both exo- and endocyclic nitrogen atoms. The dimer is linked through K-Se interactions. The reaction of 2 equiv of 8 with NiCl(2)(PMe(3))(2) in THF produces [Ni(HcdppSe)(2)], which has a distorted tetrahedral structure and exhibits anomalous (1)H, (13)C, and (31)P NMR chemical shifts owing to the proximity of the paramagnetic Ni(II) center.