Lucía Riera

Exo-metal coordination by a tricyclic [{P(µ-N-2-NC5H4)}2(µ-O)]2 dimer in [{P(µ-N-2-NC5H4)}2(µ-O)]2{CuCl·(C5H5N)2}4{2-NC5H4= 2-pyridyl, C5H5N = pyridine)

The in situ reaction of the phosphazane dimer [ClP(µ-N-2-NC5H4)]2 n(2) with CuCl in the presence of C5H5N/H2O gives the title complex [{P(µ-N-2-NC5H4)}2(µ-O)]2{CuCl·(C5H5N)2}4 n(1), containing a tricyclic [{P(µ-N-2-NC5H4)}2(µ-O)]2 ligand which is isoelectronic with species of the type [{P(µ-NR)}2NR]2.

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.

The formation of dimeric phosph(III)azane macrocycles [{P(μ-NtBu)}2·LL]2[LL = organic spacer]

The dimeric macrocycles [[P(mu-NtBu)]2.LL]2 [LL = OCH2C(Me)2CH2O (1), 2,6-(NH)2C5H3N (2), 1,2-(NH)2C6H4(3)] have been obtained by the reactions of the appropriate diols and diamines (LLH2) with the dimeric phosph(III)azane [ClP(mu-NtBu)]2. Under different conditions the reaction of 1,2-(NH2)2C6H4 with [ClP(mu-NtBu)]2 gives the monomer [[P(mu-NtBu)]2.[1,2-(NH)2C6H4]] (4) (instead of the dimer 3). Contrary to the literature, the results illustrate that the formation of dimeric macrocycles is common in these reactions and dependent among other factors on the steric demands and length of the organic spacer (LL) as well as the reaction conditions.

The folded, tetrameric phosph(III)azane macrocycle [{P(μ-NtBu)}2{1,4-(NH)2C6H4}]4

The tetrameric macrocycle [(P(mu-NtBu))2(1,4-(NH)2C6H4)]4, obtained from the reaction of the phosphazane dimer [ClP(mu-NtBu)]2 with p-phenylenediamine, has an unusual folded conformation in the solid state and contains a roughly tetrahedral arrangement of endo N-H groups for the potential coordination of anions.

Selection of the cis and trans phosph(III)azane macrocycles [{P(µ-NtBu)}2(1-Y-2-NH-C6H4)]2(Y = O, S)

The 1 : 1 reactions of [ClP(mu-NtBu)]2 with the difunctional aromatic amines 1,2-1-YH-2-NH2-C6H4 in the presence of Et3N give the dimeric phosph(III)azane macrocycles [{P(mu-NtBu)2(1-Y-2-HN-C6H4)]2, predominantly as the cis isomer in the case of Y=O (1.cis) and as the trans isomer for Y=S (2.trans). Model M.O. calculations suggest that the selection of the cis and trans isomers is not thermodynamically controlled. The alternative isomers 1.trans and 2.cis are generated exclusively by the deprotonation of the model intermediates [(1-Y-2-NH2-C6H4)P(mu-NtBu)]2[Y=O (3), S (4)] with nBuLi followed by cyclisation with [ClP(mu-NtBu)]2. The solid-state structures of 1.cis/trans(50 : 50), 2.cis, 3 and 4 are reported.