Reactions of Sn(NMe2)2 with MPHCy: the effects of alkali metal phosphide coupling (Cy=cyclohexyl; M=Li, Na, K, Rb).

The reactions of the SnII base Sn(NMe2)2 with CyPHM (Cy=cyclohexyl) produce a range of products, depending primarily on the alkali metal (M) involved. The 1:3 stoichiometric reaction of Sn(NMe2)2 with CyPHNa in the presence of the Lewis base donor PMDETA (PMDETA=(Me2NCH2CH2)2NMe) gives [(NaPMDETA)2{Sn(mu-PCy)}3] (3), containing the electron-deficient [{Sn(mu-PCy)}3]2- dianion. Natural bond order (NBO) and electron localisation function (ELF) calculations show that this species is described most appropriately by a two-electron, three-centre Sn3 bonding model. Evidence that 3 results from phosphide coupling is provided by the 1:1 reaction of Sn(NMe2)2 with CyPHNa in the presence of PMDETA, which gives 3 and trace amounts of (NaPMDETA)2[{Sn(mu-PCy)}2(mu-PCyPCy)] (4) (containing one PCyPCy2- dianion). Greater extents of phosphide coupling are observed as the size of the Group 1 metal is increased. Thus, the 1:3 reaction of Sn(NMe2)2 with CyPHK in THF gives the co-crystalline product {(K2 THF)2[{Sn(mu-PCyPCy)}2(mu-PCy)]}0.9{(K2 THF)2[{Sn(mu-PCy)}2(mu-PCyPCy)]}0.1 (5) (containing [{Sn(mu-PCyPCy)}2(mu-PCy)]2- and [{Sn(mu-PCy)}2(mu-PCyPCy)]2- dianions), whereas the analogous reaction of Sn(NMe2)2 with RbPHCy gives [RbPMDETA{(CyP)3SnP(H)Cy}] (6) (containing a cyclic {(CyP)3Sn} unit).

Highly selective epoxidation of styrene using a transition metal-aluminium(III) complex containing the [MeAl(2-py)3]- anion (2-py = 2-pyridyl).

The reactions of [MeAl(2-py)3Li.thf] (1) with FeCl2 or Cp2Mn in toluene-thf give simple access to the Group 13-transition metal heterometallic complexes [{MeAl(2-py)3}2M][M = Fe (2), Mn (3)]; complex has been shown to be a highly selective styrene epoxidation catalyst in air.

Selection of a pentameric host in the host-guest complexes [[[[P(mu-NtBu)]2(mu-NH)]5].I]-[Li(thf)4]+ and [[[P(mu-NtBu)]2(mu-NH)]5].HBr.THF.

The structures of the host-guest complexes [[[[P(mu-NtBu)]2(mu-NH)]5]I]-.[Li(thf)4]+ [2.I[Li(thf)4]] and [[[P(mu-NtBu)]2(mu-NH)]5].HBr.THF (2.HBr.THF) show that increased distortion of the framework of the pentameric macrocycle [[[P(mu-NtBu)]2(mu-NH)]5] (2) occurs with the larger halide ions. Theoretical studies show that the thermodynamic stabilities of the model host-guest anions [2.X]- (X=Cl, Br, I) are in the order Cl- approximately Br->I-, that is, the reverse of the templating trend observed experimentally. These studies support the view that the selection of the pentamer 2 over the tetramer [[[P(mu-NtBu)]2(mu-NH)]4] (1) is kinetically controlled, a conclusion which is also consistent with the previous observation that the frameworks of 1 and 2 are not in dynamic equilibrium with each other.

Synthesis and deprotonation of P-H-functionalised phosph(III)azanes; borohydride dependency on the formation of cis- or trans-[HP(mu-NtBu)2PNtBuH].

The reaction of [ClP(muNtBu)2PNtBuH] (1) with LiBsBu3H yields trans-[HP(muNtBu)2PNtBuH] (2), by contrast, reaction with LiBEt3H yields cis-[HP(mu-NtBu)2PNtBuH] (3). Compounds and represent the first examples of P-H-functionalised cyclophosph(III)azanes. Deprotonation of with BnNa (Bn=benzyl) gives the first example of a secondary phosphine-functionalised cyclodiphosph(III)azane anion [HP(mu-NtBu)2PNtBu]- (4).

Steric control in the oligomerisation of phosphazane dimers; towards new phosphorus-nitrogen macrocycles.

The reaction of [ClP(mu-NtBu)]2 (1) with H2O (1 : 2 equivalents) in the presence of excess Et3N gives the new chain compound [(mu-O)[P(mu-NtBu)2P(H)=O]2] (3), consisting of two P2N2 rings linked by a mu-O atom and terminating in P(V)(H)=O groups. A similar chain species is obtained from the reaction of the lithiate of [(tBuNH)P(mu-NtBu)2P(H)=O] (5) with [ClP(mu-NtBu)2P(NHtBu)] (2), the product being [(mu-O)[P(mu-NtBu)2P(NHtBu)]2] (6). Compounds 3 and 6 are the first examples of O-bridged chain phosphazanes and potential precursors to new phosphorus-nitrogen macrocycles. The syntheses and X-ray structures of 3, 5 and 6 are reported.

thermodynamic/kinetic control in the isomerization of the [[tBuNP(mu-NtBu)]2]2- ion.

The unique structure of [(tBuN)(2)PK]( infinity ) (2) (containing [(tBuN)(2)P](-) monoanions) is in stark contrast to the previously reported Li(+) analogue [[[tBuNP(mu-NtBu)](2)](2)]Li(4) (1) (containing the dimeric [[tBuNP(mu-NtBu)](2)](2-) ion). DFT and (31)P NMR spectroscopic studies reveal that the formation of the monoanion arrangements are most thermodyamically favored for Li, Na, and K, 1 being the product of kinetic control and 2 being the product of thermodynamic control.

Synthesis and structure of [(Sn(mu-PCy))3(Na x PMDETA)2], containing an electron-deficient [(Sn(mu-PCy))3]2- dianion.

The reaction of CyPHNa with Sn(NMe2)2 in the presence of PMDETA (= (Me2NCH2CH2)2NMe) gives the title compound [(Sn(mu-PCy))3(Na x PMDETA)2] (1), containing an electron-deficient [(Sn(mu-PCy))]3(2-) dianion with a novel two-electron, three centre (2e-3c) bonding arrangement.

Templating and selection in the formation of macrocycles containing [[P(micro-NtBu)(2)](micro-NH)](n) frameworks: observation of halide ion coordination.

Amination of [ClP(micro-NtBu)](2) (1) using NH(3) in THF gives the cyclophospha(III)zane dimer [H(2)NP(micro-NtBu)](2) (2), in good yield. (31)P NMR spectroscopic studies of the reaction of 1 with 2 in THF/Et(3)N show that almost quantitative formation of the cyclic tetramer [[P(micro-NtBu)](2)(micro-NH)](4) (3) occurs. The remarkable selectivity of this reaction can (in part) be attributed to pre-organisation of 1 and 2, which prefer cis arrangements in the solid state and solution. The macrocycle 3 can be isolated in yields of 58-67 % using various reaction scales. The isolation of the major by-product of the reaction (ca. 0.5-1 % of samples of 3), the pentameric, host-guest complex [[P(micro-NtBu)(2)](2)(micro-NH)](5)(HCl).2 THF] (4.2 THF), gives a strong indication of the mechanism involved. In situ (31)P NMR spectroscopic studies support a stepwise condensation mechanism in which Cl(-) ions play an important role in templating and selection of 3 and 4. Amplification of the pentameric arrangement occurs in the presence of excess LiX (X=Cl, Br, I). In addition, the cyclisation reaction is solvent- and anion-dependent. The X-ray structures of 2 and 4.2 THF are reported.

Formation of double cubanes [Sn(7)(NR)(8)] in the reactions of pyridyl and pyrimidinyl amines with Sn(NMe(2))(2): a synthetic and theoretical study.

In contrast to the reactions of Sn(NMe(2))(2) with unfunctionalized primary amines (RNH(2)), which yield the simple imido Sn(II) cubanes [SnNR](4), the reactions of 2-pyridyl or 2-pyrimidinyl amines give the mixed-oxidation-state Sn(II)/Sn(IV) double cubanes [Sn(7)(NR)(8)]. In addition to [Sn(7)[2-N(5-Mepy)](8)] x 2thf (1 x 2thf) (py = pyridine) and [Sn(7)[2-N(pm)](8)] x 0.33thf (2 x 0.33thf) (pm = pyrimidine), which were communicated previously, the syntheses and structures of the new complexes [Sn(7)[2-N(4-Mepm)](8)] x 2thf (3 x 2thf), [Sn(7)[2-N(4,6-Me(2)pm)](8)] x 4thf (4 x 4thf), [Sn(7)[2-N(4-Me-6-MeO-pm)](8)] (5), and [Sn(7)[2-N(4-MeO-6-MeO-pm)](8)] (6) are reported. Model DFT calculations on the reactions of Sn(NMe(2))(2) with 2-pmNH(2) or PhNH(2), producing the cubanes [Sn[2-N(pm)]](4) and [SnNPh](4) (respectively), and the corresponding double cubanes [Sn(7)[2-N(pm)](8)] and [Sn(7)(NPh)(8)], show that the presence of intramolecular Sn...N bonding which spans the cubane halves of the complexes is crucial to the formation of the double-cubane structure.

Suggestion of a "twist" mechanism in the oligomerisation of a dimeric phospha(III)zane: insights into the selection of adamantoid and macrocyclic alternatives.

The reaction of the dimeric phospha(III)zane [ClP(mu-Npy)]2 (1) (py = 2-pyridyl) with pyNHLi (2:1 equivalents, respectively) in THF/Et3N leads to rapid formation of the bicyclic nona-phospha(III)zane [[ClP(Npy)2]2-[P2(Npy)]] (2). This novel rearrangement can be rationalised by a mechanism involving "twisting (or swivelling)" of the central P(mu-Npy)P fragment of the presumed intermediate [[ClP(mu-Npy)2P]2(mu-Npy)] (3), a process that provides a fundamental mechanistic relationship between the majority of previously reported imidophosphospha(III)zanes. This process is fundamentally reliant on relief from ring strain on going from the four-membered ring units of 3 to the six-membered units of 2. The rearrangement observed for 1 is suppressed on steric grounds by Me-substitution of the pyridine ring at the 6-position, the dimeric phosphazane [ClP(mu-N-6-Me-py)]2 (4) (6-Me-py = 6-methyl-2-pyridyl) being formed almost exclusively in the 1:1 reaction of PCl3 with 6-Me-pyNHLi. The syntheses and X-ray structures of 1, 2 and 4 are reported, together with 31P NMR spectroscopic and DFT calculational studies of the conversion of models of 1 into 2. The combined studies pinpoint relief from ring strain as the key factor dictating the rearrangement.

Reaction of Group 15 Trichlorides ECl3 with the Anion [Mo2 Cp2 (CO)4 (µ-PH2 )]- ; Synthesis and Characterization of the First Complexes Featuring a Hetero µ,η2 -PE ligand (E=As, Sb).

An Me2 PE tetrahedrane framework is seen in complexes 2 a-c (E=P, As, Sb), which are prepared from the appropriate trichlorides and 1 in THF. The structures of the new antimony- and arsenic-containing compounds 2 b and 2 c have been determined-this is the first structural characterization of complexes with µ,η2 -PE heteroligands from elements of Group 15.