Reactions of the ferrocene-phosphines FcPH₂ and 1,1′-Fc′(PH₂)₂ with excess formaldehyde gives the new hydroxymethylphosphines FcP(CH₂OH)₂ 1 and 1,1′-Fc′[P(CH₂OH)₂]₂ 2, respectively. Phosphine 1 is an air-stable crystalline solid, whereas 2 is isolated as an oil. Reaction of 1 with H₂O₂, S₈ or Se gives the chalcogenide derivatives FcP(E)(CH₂OH)₂ (E=O, S or Se), whilst reaction of 2 with S8 gives 1,1′-Fc′[P(S)(CH₂OH)₂]₂, which were fully characterised. Phosphine 1 was also characterised by an X-ray crystal structure determination

Alley, Steven R.

Henderson, William

Inorganic Chemistry Communications

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Steven R. Alley

William Henderson

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New ferrocene-derived hydroxymethylphosphines: FcP(CH2OH)2 [Fc=(η5-C5H5)Fe(η5-C5H4)] and the dppf analogue 1,1′-Fc′[P(CH2OH)2]2 [Fc′=Fe(η5-C5H4)2]

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New ferrocene-derived hydroxymethylphosphines: FcP(CH₂OH)₂ [Fc=(η⁵-C₅H₅)Fe(η⁵-C₅H₄)] and the dppf analogue 1,1′-Fc′[P(CH₂OH)₂]₂ [Fc′=Fe(η⁵-C₅H₄)₂]

Research Commons@Waikato

 1 Correspondence to: Associate Professor W. Henderson, Department of Chemistry, University of Waikato, Private Bag 3105, Hamilton, New Zealand e-mail: w.henderson@waikato.ac.nz FAX:  0064-7-838-4219  New ferrocene-derived hydroxymethylphosphines: FcP(CH2OH)2 [Fc = (5-C5H5)Fe(5-C5H4)] and the dppf analogue 1,1'-Fc'[P(CH2OH)2] [Fc' = Fe(5-C5H4)2]  Steven R. Alley and William Henderson* Department of Chemistry, University of Waikato, Private Bag 3105, Hamilton, New Zealand      Received                 Abstract  Reactions of the ferrocene-phosphines FcPH2 and 1,1'-Fc'(PH2)2 with excess formaldehyde gives the new hydroxymethylphosphines FcP(CH2OH)2 1 and 1,1'-Fc'[P(CH2OH)2]2 respectively.  Phosphine 1 is an air-stable crystalline solid, whereas 2 is  2 isolated as an oil.  Reaction of 1 with H2O2, S8 or Se gives the chalcogenide derivatives FcP(E)(CH2OH)2 (E = O, S or Se), whilst reaction of 2 with S8 gives 1,1'-Fc'[P(S)(CH2OH)2]2, which were fully characterized.  Phosphine 1 was also characterised by an X-ray crystal structure determination.  Keywords:  Ferrocene compounds; Hydroxymethylphosphines; Crystal structure; Phosphine chalcogenides               1.  Introduction   Hydroxymethylphosphines, containing PCH2OH groups, have been known for many years [1] but are attracting recent interest for their versatile reactivity [2] and ability to render metal complexes water-soluble, with uses ranging from catalysis,[2,3] metal complex immobilisation [4] and biomedical applications. [2,5] We have reported the first example of a ferrocene-derived hydroxymethylphosphine, FcCH2P(CH2OH)2, and some derivatives thereof. [6] In separate recent reports, cyclophosphazene derivatives of the phosphine sulfide FcCH2P(S)(CH2OH)2 [7] and the methyl-substituted derivative FcCH(Me)P(CH2OH)2 [8] have been studied.  In this Communication we report the synthesis of two new ferrocenyl hydroxymethylphosphines, FcP(CH2OH)2 and 1,1'-Fc'[P(CH2OH)2]2.  The latter is the hydroxymethyl analogue of dppf, 1,1'-Fc'(PPh2)2, which has been very extensively investigated. [9]   3 2.  Results and discussion   A general synthesis for the synthesis of hydroxymethylphosphines utilises the ready reactivity of primary phosphines towards formaldehyde. [1,2] Reaction of the known primary phosphines FcPH2 [10] and 1,1'-Fc'(PH2)2 [11] with excess aqueous formaldehyde gave the hydroxymethylphosphines FcP(CH2OH)2 1 and 1,1'-Fc'[P(CH2OH)2]2 2 respectively.  Several products were initially obtained in each case, and are presumably the formaldehyde adducts, containing P-(CH2O)nH groups [12]; excess formaldehyde was removed by exposure of the crude products to a dynamic vacuum (ca. 1 mmHg) for 24 h.  Phosphine 1 ( 31P -24.7) is an orange crystalline solid, soluble in polar organic solvents, and indefinitely stable in air.  The 1H NMR spectrum shows that the CH2 protons are in unique environments, with a geminal coupling of 13 Hz.  This effect was not observed in the related compounds FcCH2P(CH2OH)2 or FcCH2P(S)(CH2OH)2 suggesting that the closer proximity of the bulky Fc group may be causing restricted rotation in the P-CH2 and/or CH2-O groups.  The positive ion electrospray (ES) mass spectrum of 1 in methanol at a cone voltage of 20 V with added AgNO3 [13] gave a single ion at m/z 663 due to the [2M + Ag]+ ion.  The X-ray structure determination of 1‡ was carried out to unambiguously confirm the formulation of the compound as the bis(hydroxymethyl)phosphine, and the molecular structure is shown in Fig. 1.  The network of hydrogen bonding involving the OH groups is very similar to that of FcCH2P(CH2OH)2 [6] with the molecules arranged into chains, crosslinked by hydrogen bonds, resulting in each molecule being involved in hydrogen bonding interactions with four other molecules.  There are two distinct types of hydrogen  4 bonds, H(4)---O(1), which link two chains together, and H(3)---O(2), which link adjacent molecules in the same chain together, resulting in the formation of linked ten-membered hydrogen bonded rings, Figure 2.  Reaction of 1 with hydrogen peroxide, sulfur or grey selenium under sonication gives the phosphine oxide 3 ( 31P 47.6), sulfide 4 ( 31P 38.2) and selenide 5 ( 31P 39.1, 1J(PSe) 701 Hz) respectively; all are crystalline orange solids.  X-ray crystal structure analyses have also been performed on these derivatives, and a detailed comparison of the hydrogen bonding trends will be described elsewhere.  Phosphine 2 was unable to be obtained as a crystalline solid, and unlike 1, this phosphine is slightly air-sensitive, and a satisfactory elemental analysis was not obtained.  The ES mass spectrum of 2 with added AgNO3 showed the [2M + Ag]+ ion (m/z 847) at low cone voltages (ca. 20V) and [M + Ag]+ (m/z 477) at higher cone voltages (e.g. 60 V).  Further characterisation was by means of the formation of the disulfide derivative 6, for which satisfactory microanalytical data were obtained.  Like the parent phosphine 1, the sulfide and selenide derivatives 4 - 6 also show inequivalent CH2 protons, with geminal 2J(HH) coupling of ca. 13 Hz.  In conclusion, we have synthesised mono- and bis-substituted ferrocenyl-hydroxymethylphosphines, where one or both cyclopentadienyl rings are substituted with water-solubilising and reactive P(CH2OH)2 groups. Given the importance of dppf as a ligand [9], more detailed studies on the coordination chemistry of the related phosphine 2 are clearly warranted.    5 3.  Experimental   General experimental details have been described elsewhere [6] and the atom numbering scheme is given in ref. [14]. The compounds FcPH2 [10] and 1,1'-Fc'(PH2)2 [11] were prepared by modifications of the literature methods.  3.1  Preparation of FcP(CH2OH)2 1   Aqueous formaldehyde (0.25 mL, 40% w/v) was added to a solution of FcPH2 (0.26 g, 1.2 mmol) in thf (5 mL) under nitrogen, and the solution stirred for 18 h.  The volatiles were removed under vacuum, and the crude product held under vacuum for ca. 72 h to remove excess formaldehyde, giving an orange microcrystalline solid (0.33 g, 96%).  M.p. 100-106 °C.  Found:  C, 51.8;  H, 5.5.  C12H15FeO2P requires C, 51.8; H, 5.4%.  31P-{1H} NMR (CDCl3),  -24.7.  1H NMR (CDCl3),  2.56 (2H, br s, OH), 4.24 (5H, s, C5H5), 4.30 [2H, dd, 2J(HH) 13, 3J(HH) 5, CH2], 4.40 (2H, s, C5H4), 4.45 [2H, br d, 2J(HH) 13, CH2], 4.50 (2H, s, C5H4).  13C-{1H} NMR (CDCl3),  62.90 [d, J(PC) 17, PCH2OH], 69.08 s), 70.24 [d, J(PC) 3.8], 73.22 [d, J(PC) 14)].  3.2  Preparation of 1,1'-Fc'[P(CH2OH)2]2 2   Following the method for 1, 40% formaldehyde (0.41 mL) was added to a solution of 1,1'-Fc'(PH2)2 (0.24 g, 0.97 mol) in thf (5 mL) under nitrogen, and the mixture stirred for 24 h.  Workup gave 0.348 g (98%) of 2 as a viscous orange-brown oil.  31P-{1H} NMR  6 (d6-DMSO),  -31.0.  1H NMR (d6-DMSO),  4.02 (8H, m, CH2), 4.34 (4H, br s, C5H4), 4.39 [4H, d, 3J(PH) 1.7, C5H4], 4.89 (3.6H, br s, OH). 13C-{1H} NMR (d6-DMSO),  61.02 [d, J(PC) 6.6, PCH2OH], 72.45 (s, br), 74.56 [d, J(PC) 13], 91.18 [d, J(PC) 9].  3.3  Preparation of phosphine oxide, sulfide and selenide derivatives 3 - 6  The appropriate phosphine was treated with H2O2, S8 or grey Se respectively, followed by standard workup procedures. 3; Yield 97%, m.p. 171-176 C. Found C, 49.0; H, 5.3.  C12H15FeO3P requires C, 49.0; H, 5.1%. 1H NMR (d6-DMSO),  3.97 (4H, br s, PCH2OH), 4.39 (5H, s, H4), 4.54 (4H, br s, H2/H3), 5.39 (2H, br s, PCH2OH). 13C-{1H} NMR (d6-DMSO),  59.52 [d, 1J(PC) 84, PCH2OH], 70.88 (s), 72.61 [d, J(PC) 10], 72.75 [d, J(PC) 11], C1 not observed. 4; Yield 99%, m.p. 122-126 C. Found C, 46.3; H, 4.9.  C12H15FeO2PS requires C, 46.5; H, 4.9%. 1H NMR (CDCl3),  2.76 [2H, dd, 3J(HH) 6, 3J(PH) 6, CH2OH], 4.05 [2H, ddd, 2J(HH) 13, 3J(HH) 4.2, 2J(PH) 1.6, CH2], 4.15 [2H, ddd, 2J(HH) 13, 3J(HH) 6.3, 2J(PH) 1.6 CH2], 4.36 (5H, s, H4), 4.52 [2H, dt, 3J(HH) 3.6, 4J(PH) 1.7, H3), 4.56 [2H, dt, 3J(HH) 3.5, 3J(PH) 1.7, H2]. 13C-{1H} NMR (CDCl3),  61.04 [d, J(PC) 59, PCH2OH], 70.03 (s), 71.55 [d, J(PC) 12], 72.13 [d, J(PC) 9]. 5; Yield 95%, m.p. 116-118 C. Found C, 40.8; H, 4.5.  C12H15FeO2PSe requires C, 40.4; H, 4.2%. 1H NMR (CDCl3),  3.1 (2H, br s, CH2OH), 4.08 [2H, d, 2J(HH) 12, CH2], 4.20 [2H, d, 2J(HH) 12, CH2], 4.36 (5H, s, H4), 4.53 (2H, br s, H2), 4.60 (2H, br s, H3). 13C-{1H} NMR (CDCl3),  60.92 [d, J(PC) 51, PCH2OH], 70.14 (s), 72.16 [d, J(PC) 9], 72.28 [d, J(PC) 8.5], C1 not observed.  7 6; Yield 83%, m.p. 138-143 C. Found C, 38.8; H, 4.7.  C14H20FeO4P2S2 requires C, 38.7; H, 4.6%. 1H NMR (d6-DMSO),  4.05 [4H, dd, 2J(HH) 13.4, 3J(HH) 5.9, CH2], 4.12 [4H, dd 2J(HH) 13.4, 3J(HH) 4.2, CH2], 4.72 (4H, m, H3), 4.76, (4H, m, H2), 5.69 (4H, br m, PCH2OH). 13C-{1H} NMR (d6-DMSO),  62.65 [d, 1J(PC) 65, PCH2OH], 73.58 [d, J(PC) 78, C1], 74.80 [d, J(PC) 10], 74.92 [d, J(PC) 9].    4.  Supplementary material   Crystallographic data (excluding structure factors) for the structure described in this paper have been deposited with the Cambridge Crystallographic Data Centre (publication number CCDC ######).  Copies of the data can be obtained free of charge on application to CCDC, 12 Union Road, Cambridge CD2 1EZ, UK, e-mail deposit@ccdc.cam.ac.uk.    Acknowledgements   We thank the University of Waikato for financial support, including a scholarship (to SRA), Assoc. Prof. Cliff Rickard (University of Auckland) for providing the X-ray data set, and Professor Brian Nicholson for assistance with crystallography.  References   8 [1] A. W. Frank, D. J. Daigle and S. L. Vail, Textile Res. J. (1982) 738. [2] K. V. Katti, H. Gali, C. J. Smith and D. E. Berning, Acc. Chem. Res. 32 (1999) 9;  K. V. Katti, Curr. Sci. 70 (1996) 219;  D. E. Berning, K. V. Katti, C. L. Barnes and W. A. Volkert, J. Am. Chem. Soc. 121 (1999) 1658. [3] B. Dreien-Hölscher and J. Heinen, J. Organomet. Chem. 570 (1998) 141; A. Fukuoka, W. Kosugi, F. Morishita, M. Hirano, L. McCaffrey, W. Henderson and S. Komiya, Chem. Commun. (1999) 489; A. Salvini, P. Frediani, M. Bianchi, F. Piacenti, L. Pistolesi and L. Rosi, J. Organomet. Chem. 582 (1999) 218. [4] T. Shido, T. Okazaki and M. Ichikawa, J. Mol. Catal. 120 (1997) 33. [5] See e.g. C. J. Smith, N. Li, K. V. Katti, C. Higginbotham and W. A. Volkert, Nucl. Med. Biol. 24 (1997) 685;  D. E. Berning, K. V. Katti, W. A. Volkert, C. J. Higginbotham, and A. R. Ketring, Nucl. Med. Biol. 25 (1998) 577;  R. Schibli, S. R. Karra, H. Gali, K. V. Katti, C. Higginbotham and W. A. Volkert, Radiochim. Acta 83 (1998) 211.  [6] N. J. Goodwin, W. Henderson, B. K. Nicholson, J. K. Sarfo, J. Fawcett and D. R. Russell, J. Chem. Soc., Dalton Trans.  (1997) 4377. [7] N. D. Reddy, A. J. Elias and A. Vij, Inorg. Chem. Commun. 3 (2000) 29;  K. Muralidharan, N. D. Reddy and A. J. Elias, Inorg. Chem. 39 (2000) 3988. [8] T. V. V. Ramakrishna, A. J. Elias and A. Vij, J. Organomet. Chem. 602 (2000) 125. [9] K.-S. Gan and T. S. A. Hor in Ferrocenes, Eds. A. Togni and T. Hayashi, VCH, Weinheim, 1995, Ch. 1.  9 [10]  C. Spang, F. T. Edelmann, M. Noltemeyer and H. W. Roesky, Chem. Ber. 122 (1989) 1247. [11] M. J. Burk and M. F. Gross, Tetrahedron Lett. 35 (1994) 9363. [12] P. A. T. Hoye, P. G. Pringle, M. B. Smith and K. Worboys, J. Chem. Soc., Dalton Trans. (1993) 269. [13]  W. Henderson and G. M. Olsen, Polyhedron 15 (1996) 2105. [14] S. R. Alley and W. Henderson, J. Organomet. Chem., in press. [15] R. H. Blessing, Acta Crystallogr. A51 (1995) 33. [16] G. M. Sheldrick, SHELX-97 programs for solution and refinement of crystal structures, University of Göttingen, 1997.   10 Footnotes   ‡ Crystals were obtained by diffusion of pentane vapour into a CH2Cl2-MeOH (10:1) solution at -20 °C.  Crystal data for 1:  C12H14FeO2P, M = 278.06, Monoclinic, space group P21/c, a = 12.2386(1), b = 6.1101(1), c = 16.3344(2) Å,  = 110.941(1) °, V = 1140.79(3) Å3, Z = 4, Dcalc = 1.619 g cm-3, F(000) = 576, Mo-K radiation,  = 0.71073 Å, (Mo-K) = 1.44 mm-1.  Data [10314 reflections, 2357 unique, with Rint 0.0327] were collected at 150(2) K on a Siemens SMART CCD diffractometer in the range 1.8 <  < 26.5°, and corrected for absorption using SADABS [15].    The structure was solved using the direct methods option of SHELXL-97 [16] and developed routinely using full-matrix least-squares refinement based on Fo2.  All non-hydrogen atoms were refined using anisotropic temperature factors and hydrogen atoms were found from peaks of residual electron density in the penultimate electron density map and were refined with isotropic temperature factors. Refinement converged at R1 [I > 2(I)] 0.254, wR2 0.0659, with the weighting scheme w = [2(Fo)2 + (0.0422P)2 + 0.29P]-1 and P = (Fo2 + 2Fc2)/3 used in latter stages of refinement. The largest residuals in the final density map were +0.431 and -0.463 e Å-3.    11 Captions for Figures  Fig. 1   Molecular structure of FcCH2P(CH2OH)2 1, with ellipsoids at the 50% probability level.  Selected bond lengths (Å) and angles (°); C(11)-P(1) 1.809(2), P(1)-C(1)  1.849(2), P(1)-C(2) 1.850(2),  C(1)-O(1)  1.425(2), C(2)-O(2)  1.423(2),  C(11)-P(1)-C(1)  99.18(8), C(11)-P(1)-C(2)  103.07(9), P(1)-C(1)-O(1)  110.82(13), P(1)-C(2)-O(2)  115.83(13).  Fig. 2.   Hydrogen bonding in FcP(CH2OH)2, showing the formation of linked ten-membered rings.    

Acta Crystallogr.

programs for solution and refinement of crystal structures,

Soc., Dalton Trans.

New ferrocene-derived hydroxymethylphosphines: FcP(CH₂OH)₂ [Fc=(η⁵-C₅H₅)Fe(η⁵-C₅H₄)] and the dppf analogue 1,1′-Fc′[P(CH₂OH)₂]₂ [Fc′=Fe(η⁵-C₅H₄)₂]

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