Aspects of the coordination chemistry of rac-trans-1,2-diphosphinocyclohexane and the preparation of reinforced 9aneP₃and 9anePN₂macrocycles

Abstract

Racemic trans-1,2-diphosphinocyclohexane (t-chxnP2) has been synthesised and its coordination chemistry to Cu(I), Ag(I), Mn(I) and Fe(II) investigated. Compounds of empirical formula [Cu(t-chxnP2)2]BF4 and [Ag(t-chxnP2)2]BF4 have been prepared as isomeric mixtures and the solid-state structure of both complexes determined by single-crystal techniques. The Cu(I) complex is a monomeric species which crystallises with one ligand bearing the R,R configuration and the other being the S,S isomer whereas the Ag(I) complex crystallises as a polymer containing both chelating and bridging t-chxnP2 ligands with 3- and 4-coordinate Ag(I) centres and argentophilic bonds. The bidentate diprimary phosphine has been coordinated to Mn(I) and Fe(II) templates and used as a P2 unit for the formation of chiral (albeit racemic) 1,4,7-triphosphamacrocycles (9aneP3). In addition 1R,2R- and 1R,2S-diaminocyclohexane (chxn) have been coordinated to Mn(I) and Fe(II) templates and similarly employed for the formation of new 1,4-diamino-7-phosphamacrocycle (9anePN2) complexes.

Cyclononanes: The extensive chemistry of fundamentally simple ligands

“…No metal complexes of the ligand were reported but the methyl iodide salt [9] The majority of the reports related to [9]aneP 3 type cyclononane ligands has arisen from one group, much of the chemistry utilising the activated, electrophilic ortho-fluorophenyl substituent on a neighbouring pnictide donor [288][289][290][291][292][293][294][295][296][297][298][299].…”

“…The authors claimed that such macrocyclic systems incorporated into a membrane would have applications in separating a feed stream which included olefins and paraffins [302]. [289]. The complexes were characterised by IR and 1 H NMR spectroscopies.…”

“…The authors suggested that a coordination-induced intramolecular hydroamination had occurred to form a linear P 3 ligand and subsequent to that an undefined P 3 macrocycle. It was proposed that unbound benzyldivinylphosphine acted as a base to abstract a proton from the acidic NH 2 groups thus enabling attack of the liberated nitrogen lone pair at a coordinated benzyldivinylphosphine [289]. Complete conversion to the macrocyclic species was achieved after removal of the original reaction solvent, dissolution of the residues in THF and reaction with potassium tert- spectroscopy and elemental analysis [99], although the nickel(II) and iron(II) complexes were subsequently characterised with X-ray crystallography [304,305].…”

“…Crystal structure of [(η 4 ,κP,κP,κP-Me 2 C 4 -[1,4-bis(2-CH 2 C 6 H 4 )-7-C 6 H 5 -[b,e,h]tribenzo-1,4,7-triphosphacyclononane]-1,2)Co] +[288] Racemic trans-1,2-diphosphinocyclohexane (t-chxnP 2 ) was coordinated to Mn(I) and Fe(II) templates and used as a diphosphine unit for the formation of chiral 1,4,7triphosphamacrocycles[289].Replacement of the bromido ligand in [Mn(CO) 3 (Br)(t-chxnP 2 )] by a weakly coordinating triflate resulted in the new complex [Mn(CO) 3 (t-chxnP 2 )(OTf)]. Displacement of the triflate by tris-2-fluorophenylphosphine resulted in anA c c e p t e d M a n u s c r i p t 125 air sensitive monophosphine-bisphosphine complex.…”

“…butoxide; the macrocyclic complexes [Mn(CO) 3 (trans-chxn[9]anePN 2 Bz,H 2 )]PF 6 and [Mn(CO) 3 (cis-chxn[9]anePN 2 Bz,H 2 )]PF 6 resulted (Scheme 4) [289]. Based on the respective yields of the complexes the authors concluded that the formation of the cischxn[9]anePN 2 Bz,H 2 complex was less efficient than that of the trans-chxn[9]anePN 2 Bz,H 2 ,with this suggested to be a consequence of the different orientation of the cyclohexyl rings in two isomers[289]. The complexes exhibited 31 P NMR chemical shifts at δ P 104 and 103 ppm, respectively, with the IR spectra showing NH stretches at 3291 and 3500 cm −1 and carbonyl stretching frequencies at 2016 and 1918 cm −1 for the trans complex, and 2019 and 1910 cm −1 for the cis[289].…”