Self-assembly of a columnar polymeric calcium phosphinate derived from camphene

Abstract

(2.2 -Dimethyl bicyclo 12.2.1 J hept-3-ylmet hyl) phosphinic acid ( R PO,H,) , readily prepared from camphene and hypophosphorous acid, formed a polymeric calcium salt [{Ca( RPO,H),( RPO,H,) ( H20)}J, with both terminal and triply bridging phosphinate groups, and an overall columnar structure with an inorganic core and a pseudo-close-packed sheath of terpene moieties.The self-assembly of novel nanostructures using metal phosphates, phosphonates and phosphinates is an area of significant current interest, since such materials have applications in catalysis, ion exchange and sorptive processes. Specific examples include molecular sieve alumino-and gallo-phosphates, layered phosphonates having the ability to undergo shapeand enantio-selective ' intercalation reactions, and a vanadium phosphate which adopts a novel chiral double-helix structure.8 To date, however, studies have been largely restricted to salts of relatively simple, sterically non-demanding organophosphorus acids.We recently reported the high-yield synthesis of the phosphinic and phosphonic acids, RP02Hz 1 and RP03H2 2 respectively (R = 2,2-dimethylbicyclo[2.2.l]hept-3-ylmethyl), from inexpensive camphene (2,2-dimethyl-3-methylenebicyclo-C2.2. llheptane) and hypophosphorous (phosphinic) acid H3P02.9 Unfortunately, the attempted preparation of chiral 1 starting from (Rj( +)-camphene yielded only racemic material, as a result of acid-catalysed racemisation of the camphene; the structural stability of the RH skeleton (compared to that of the parent camphene) does however suggest that optical resolution of the enantiomers of 1 and/or 2 may be possible. The ready availability of these new organophosphorus acids suggested that metal derivatives having both novel structures and potential for materials separations (including ultimately enantioselective separations) might be accessible. We wished to undertake preliminary investigations into the structural chemistry of such metal phosphinate salts, and some of these studies are presented here.Reaction of the compound ( k )-1 t with 0.5 mol equivalent of Ca(NO3),.4HzO and an excess of urea (for pH control) for 5 d yielded a colourless solution which, upon slow evaporation, afforded colourless prismatic crystals. 1 These were characterised as the polymeric calcium salt [{Ca(RP02Hj2(RP02H2)-(H20)}J on the basis of a single-crystal X-ray study. § Owing to the relatively poor quality of the crystals, and the disorder of the R groups, arising from librational effects and possibly also from superposition of (+) and (-) enantiomers, the structure 7 Obtained by a modification of the previously reported route' by treating camphene with H,P02 (3 mol equivalents) in refluxing Pr'OH with a catalytic amount of benzoyl peroxide. The ( f )-phosphinic acid 1 has been fully characterised by NMR spectroscopy, electrospray mass spectrometry and by a single-crystal structure, full details of which will appear elsewhere.1 A solution of Ca(N03),.4H,0 (0.585 g, 2.48 mmol) with compound ( k )-1 (1 .OO g, 4.95 mmol) and urea (1.5 g, exc...

Stabilization of tautomeric forms P(OH)3 and HP(OH)2 and their derivatives by coordination to palladium and nickel atoms in heterometallic clusters with the Mo3MQ4 4+ core (M = Ni, Pd; Q = S, Se)

“…The structure re finement converged to R 1 ≈ 0.19. X ray diffraction analysis al lowed us to determine the structure of the cluster core and reveal the PhP(OH) 2 molecule included in the cavity of Q [8]. How ever, the accuracy of the interatomic distances is low and the complete composition of the compound was not determined.…”

“…The structure of the supramolecular adduct of the [Mo 3 (Ni(P(OH) 3 )S 4 (H 2 O) 8 Cl] 3+ cluster complex with cucurbit [6]uril is shown in Fig. 4.…”

Camphene-derived primary and hydroxymethyl phosphines

“…Products indicative of a retro DielsÈAlder pathway in the decomposition of camphene are observed, such as cyclopentadiene (IR stretch observed at 663 cm~1) and ethylene. Recognising that conversion of camphene to bornylene is unlikely,38 we postulate a [1,3] sigmatropic rearrangement of camphene to produce methylethylnorbornene (Scheme 1). This may then give rise to retro-DielsÈAlder decomposition producing methylethylcyclopentadiene and ethylene.…”

“…We have previously reported that the reaction of camphene with excess hypophosphorous acid under radicalcatalysed conditions gives endo-8-camphanylphosphinic acid, 2, in good yields,2 which forms a polymeric camPO 2 H 2 , calcium salt. 3 In a separate study, we described the synthesis of uranyl nitrate complexes of some camphene-derived phosphorylic compounds. 4 In this paper we describe the synthesis and characterisation of some new camphene-derived phosphines, with emphasis on the primary phosphine and camPH 2 the hydroxymethylphosphine camP(CH 2 OH) 2 .…”

Platinum(II) phosphonate complexes derived from endo-8-camphanylphosphonic acid

“…This structural motif was also seen in the polymeric calcium salt of the corresponding phosphinic acid, CamPH(O)(OH), which has a columnar structure comprising a hydrophilic, inorganic core surrounded by a sheath of camphanyl groups. [6] In this paper we report the synthesis and characterisation of some platinum(II) complexes with phosphonate ligands have attracted some interest for their biological activity, [10,11] though there are very few studies in contrast to related complexes containing phosphate ligands, because of the significance of the latter to the interactions of platinumbased anticancer drugs with DNA. [12,13,14,15] Results and discussion…”