Cyclophosphazenes as Nodal Ligands in Coordination Polymers

Abstract

Herein, we show that cyclotriphosphazenes carrying organo amino side chains, (RNH)6P3N3 [R = n-propyl (1), cyclohexyl (2), benzyl (3)], and (C4H8N)6P3N3 (4) produce supramolecular coordination compounds in conjunction with silver salts by formation of linear N-Ag-N connections via nitrogen centers of the phosphazene ring. Crystalline materials were obtained by layering methanol solutions containing phosphazene ligands with methanol solutions of AgClO4 and AgNO3. The donor ability of the anion and the steric demand of the lipophilic ligand sphere R control the topology of the coordination network: (1)2(AgClO4)3 forms a graphite-type (6,3) network. All three N(ring) atoms of the phosphazene ligand coordinate to silver ions, which, in return, linearly bridge two phosphazene ligands. The phosphazene-Ag(I) arrangement in 1(AgNO3)2 exists of zigzag chains featuring one bridging silver ion and one terminally coordinated silver ion per ligand molecule. The terminally located Ag(I) ions of neighboring chains are bridged by nitrate ions, resulting in a 2D network. Both 2(AgClO4) and 4(AgClO4) contain only one bridging silver ion per phosphazene ligand, which leaves one N(ring) site vacant and gives 1D zigzag chain arrangements. The crystal structures of 3(AgClO4)2 and 3(AgNO3)2 resemble that of 1(AgNO3)2, but show additional Ag-pi(aryl) interactions between the terminally arranged silver ions and benzyl groups. Treatment of 3 with a methanol solution containing both AgNO3 and AgClO4 leads to the heteroanion derivative 3(AgNO3)(AgClO4). Phosphazene ligands 1-3 have the ability to undergo hydrogen bonding to anions via the six NH groups, and the coordination polymers containing these ligands feature dense networks of NH...O bonds.

Solid-state synthesis of embedded single-crystal metal oxide and phosphate nanoparticles and in situ crystallization

“…[21][22][23] Precursors containing two different organometallic fragments coordinated to the phosphorus ring of a cyclotriphosphazene have not yet been successfully realized as nanomaterial precursors. [24] This method is so versatile it allows us to form many transition metals to form as oxide, phosphate and also pyrophosphates which offer high lithium-ion mobilities for fast charging lithium-ion phosphate-based cathode materials. [25] Here, we report the synthesis of new organometallic derivatives of cyclotriphosphazenes that result in individual single-crystal nanoparticles of metal oxides and phosphates embedded in an amorphous matrix after pyrolysis in air.…”

Supramolecular Structures of Cyclotriphosphazenes

“…Cyclotriphosphazenes carrying organoamino groups (RNH) 6 P 3 N 3 produce coordination polymers in conjunction with silver salts via linear N-Ag-N connections [72]. The donor strength of the anion and the steric demand of the exocyclic R group control the topology of the coordination network.…”

Ansa versus spiro selectivity in substitution reactions of a mono ansa fluorodioxycyclotriphosphazene derivative with diols

“…The determination of substitution patterns is very important for cyclophosphazene chemistry due to the fact that the multiple available pathways in these nucleophilic substitution reactions lead to a large number of cyclophosphazene derivatives [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Systematic studies of the substitution patterns will lead to a fundamental understanding of the factors which control these processes.…”

“…Systematic studies of the substitution patterns will lead to a fundamental understanding of the factors which control these processes. The substitution pattern in classic cyclophosphazene chemistry is usually governed by steric, electronic and mechanistic effects [1][2][3][14][15][16][17][18][19]21,22]. When electron-donating substituents are on the N 3 P 3 ring, the positive charge at the P-atoms is reduced and therefore non-geminal substitution patterns are observed for alcoholate and phenolate anions [1,20,21,25].…”