Cadmium and phosphorus cycling in the water column of the South China Sea: The roles of biotic and abiotic particles

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Polyhedron Vol. 9, No. 21, pp. 257!%2584, 1990 0277-5387/90 S3.00+ .I0

Printed in Great Britain 0 1990 Pergamon Press plc

TRIPODAL LIGANDS WITH MIXED DONORS. SYNTHESIS OF 2-DIPHENYLPHOSPHINOMETHYL-2-

PHENYLTHIOMETHYL-l-METHOXYPROPANE (PSO) AND

ITS TRANSITION METAL COMPLEXES

SHIUH-TZUNG LIU,* CHONG-LUNG TSAO, MINGCHU CHENG and SHIEMING PENG

Department of Chemistry, National Taiwan University, Taipei, Taiwan 10764, R.O.C.

(Received 20 March 1990 ; accepted 7 June 1990)

Abstract-A tripodal ligand containing phosphorus, sulphur and oxygen donors has been synthesized and its coordination in chromium(O), molybdenum(O), tungsten(O), man- ganese(1) and palladium(I1) complexes has been investigated. X-ray crystal structures of the chromium, tungsten and palladium compounds have been determined, and the con- formations of the six-membered chelate rings of these complexes are discussed.

The design of new polydentate ligands for coor- dination studies has been interesting and chal- lenging work. As part of our interest in tripodal terdentate ligands, we wished to synthesize such species which contain both “soft” and “hard” donor sites. Such ligands could be used to study the selectivity studies toward transition metals. In our early work, ’ we described several tripodal ligands that contain only two different donor sites, 1 and 2. However, tripodal terdentates containing three different donor atoms would be more attractive for coordination chemists. Only a few such species have been reported,2’3 and none containing phosphorus. Here, we report the syn- thesis of a tripodal phosphine ligand with three different donors, 2-diphenylphosphinomethyl-2- phenylthiomethyl-1-methoxypropane (abbreviated as PSO) 3, and its complexation toward various transition metals.

I X = OMe (P20)

2 X = SPh (P,S)

3

*Author to whom correspondence should be addressed.

RESULTS AND DISCUSSION Synthesis of Iigand

The synthetic approach to 3 is shown in Scheme 1. From 4, compound 5 was prepared according to a modification of the reported method.4 The oxetane ring was opened by the benzenethiolate anion to generate the sulphide-alcohol6. Mesylation of the hydroxy function of 6, followed by treatment with diphenylphosphide anion, produced the desired phosphine compound (+)-3, after anaerobic chro- matography of the crude product on a column of degassed silica gel. This terdentate was char- acterized by a spectroscopic method and elemental analysis. The “P NMR spectrum shows a single peak at - 24.78 ppm, upfield from the reference of 85% H3P04, which is the characteristic absorption of a tertiary phosphine.

Group VI complexes

The group VI carbonyl complexes, (PSO)M (CO),, in which M = Cr @a), MO (8b) and W (8c), were readily prepared by means of the direct ligand substitution reaction. The complexes 8a-& were made by the thermal reaction of 3 with the corresponding M(C0)6 in boiling, degassed xylene. Attempts to prepare (PSO)Mo(CO), failed. The substitution reaction of Mo(q6-cyclohepatriene) (CO), by PSO led to the isolation of 8b instead

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+iH :z .+Le 4 5 -E- SPh PhS- OH EtOH OMe 6 MsCl Et,N SPh OMs LiPPh, -3 OMe 7 Scheme 1.

of (PSO)Mo(CO),. Other thermal substitution 2). All bond distances and bond angles are within reactions or photochemical activation of 8b were normal ranges ; some selected bond distances and unable to force the oxygen donor to become co- bond angles are given in Table 2. The M-C dis- ordinated. All purified tetracarbonyl metal com- tances for both 8a and & tram to phosphorus are plexes have been identified by both spectroscopic longer than those trans to sulphur ; this effect is and elemental analyses ; their data are summarized believed to be a consequence of the presence of

in Table 1. metal-to-sulphur rc-back-donation.2*4

Crystals of 8a and & were grown from hexane and dichloromethane solvents and are isomor- phous. The structure of 8a shows the chromium centre to have an octahedral stereochemistry with four carbonyls, and the phosphorus and the sulphur donors of PSO bound to the metal (Figs 1 and

Manganese(I) complexes

From the reaction of equimolar 3 and Mn(C0)5 Br in boiling chloroform, a yellow crystalline solid of complex 9 was isolated. The IR spectrum

Table 1. Spectroscopic and analytical data of complexes 8a-8c

Complex ‘H NMR “P NMR IR WOII (A& (cm- ‘) Analysis 8a 7.56-7.34 (m, 15 H), 3.05 (s, 3 H) 37.36 (62.1) 2.82-3.09 (m, 4 H) 2.63 (dd, J = 24.6, JP--C_-H = 8 Hz, 1 H) 2.35 (dd, J = 24.6, Jp--c--H = 8 Hz, 1 H) 0.86 (s, 3 H) 8b 7.62-7.35 (m, 15 H), 3.12 (s, 3 H) 18.51 (43.3) 3.18 (d, J = 10.8 Hz, 1 H) 3.02 (d, J = 10.8 Hz, 1 H) 3.02 (d, J = 9.4 Hz, 1 H) 2.94 (d, J = 9.4 Hz, 1 H) 2.67 (dd, J = 15, JP-c_,, = 7 Hz, 1 H) 2.47 (dd, J = 15, JP_-C_-H = 7 Hz, 1 H) 0.95 (s, 3 H) 8c 7.70-7.32 (m, 15 H), 3.13 (s, 3 H) 3.36 (28.1) 3.30 (d, J = 11.4 Hz, 1 H) 3.16(d,J= 11.4Hz, 1 H) 3.01 (d, J = 5.8 Hz, 1 H) 2.94 (d, J = 5.8 Hz, 1 H) 2.80 (dd, J = 14.6, JP--C_-H = 8 Hz, 1 H) 2.60 (dd, J = 14.6, Jpz_” = 8 Hz, 1 H) 0.97 (s, 3 H) 2008 1960 1912 1885 2019 1976 1916 1891 2014 1929 1910 1883 Cz8Hz70PSCr Calc. C, 60.2 ; H, 4.9 Found C, 60.1; H, 5.1 Cz8H2,0PSMo Calc. C, 55.8 ; H, 4.5 Found C, 56.2 ; H, 4.5 Cz,H2,0PSW Calc. C, 48.7; H, 3.9 Found C, 49.5 ; H, 4.0

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Tripodal ligands with mixed donors 2581

Fig. 1. The ORTEP drawing of 8e.

(v(C0) = 2034, 1961, 1907 cm- ‘) of 9 shows

three terminal CO stretches in j&-geometry? Both 3’P and ‘H NMR spectra indicate that phosphorus and sulphur donors bind to the metal centre with the oxygen site uncoordinated. This evidence indi- cates the structure of 9 to be an octahedral complex with phosphorus, sulphur and bromide in a fat- arrangement.

Another way to achieve complex 9 is by the reac- tion of 3 and Mnr.(CO)io to generate [(PSO)Mn (CO),12 (lo), followed by treatment with bromine (Scheme 2). It is interesting to note that both IR and ‘H NMR spectra of 10 are similar to those of 9 ; only the 31P chemical shifts for both com- plexes have a slight difference (6 25.66 of 9 vs 6 27.63 of 10). However, we have not determined the exact structure of 10.

Fig. 2. The ORTEP drawing of 8a (ph&yl groups omitted

KO),Mn&

[(PSO I Mn (COlaI

IO Scheme 2.

Palladium(I1) complex

The reaction of equimolar amounts of 3 and PdCl* in acetonitrile afforded the desired complex (PSO)PdC12 (11) as a yellow, crystalline solid upon recrystallization. Both ‘H and 31P NMR spectro- scopic data of the compound indicate that the potentially terdentate PSO ligand acts in a bidentate mode with phosphorus and sulphur atoms binding to palladium metal in a c&fashion. This structure has been further determined by the single-crystal X- ray diffraction method. Figure 3 shows an ORTEP view of the complex with all non-hydrogen atoms labelled. The coordination geometry around pal- ladium is a square-planar arrangement with the palladium atom slightly [O. 197(4) A] out of the plane defined by S,P,Cl(l),Cl(2). Selected bond dis-

Table 2. Selected bond distances (A) and bond angles (“) of complexes 8a, 8c and 11

8a M = Cr & M=W M-P M-S M-C(7) M--C(8) M-C(9) M-C(lO) M-C(ll) M-X(12) P-C(l) s-c(3) C(ltc(2) C(2)-C(3) S-M-P P-M-X( 7) S-M-C(lO) C(7)-M-C(lO) C(8)-M-C(9) P-M-C( 11) S-M-C(2) C( 1 l)-M-C( 12) 2.385(2) 2.420(2) 1.806(6) 1.911(7) 1.879(6) 1.820(6) 1.820(S) 1.82(l) 1.822(6) 1.81(l) 1.549(9) 1.54(2) 1.538(8) 1.56(2) 91.85(7) 88.8(2) 92.0(2) 87.8(3) 174.7(3) 89.7( 1) 89.8(4) 91.2(4) 89.8(6) 175.6(5) 2.510(3) 2.54q4) 1.88(l) 2.07(l) 1.82(2) 1.94(l) 11 M = Pd 2.235(2) 2.285(2) 2.289(2) 2.381(2) 1.830(6) 1.824(7) 1.524(7) 1.518(g) 97.81(6) 86.26(7) 84.77(7) 91.15(7) for clear view).

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Fig. 3. ORTEP drawing of complex 11.

tances and angles are listed in Table 2. The Pd-Cl bond tram to the phosphorus atom is longer, as expected, than that trans to the sulphur atom, prob- ably due to the “trans effect”.

Conformational analysis

Table 3 presents all torsional angles around the six-membered chelate rings of the complexes, which also facilitates their comparison. The characteristic

+g, -g alternations indicate the conformations of the six-membered chelate rings of Sa, SC and 11 to be in chair forms, which are considered the most stable. 6,7 However, these chair conformations are all slightly distorted, especially in the palladium complex (Fig. 3).

In the previous investigation,‘“,ib we found that the conformations of (P,S)Mo(CO), and (P,O)Cr (CO),, were in twist-boat forms mainly due to the steric interactions of substituents along the chel-

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.SPh

Table 3. Torsional angles (“) around the six-membered chelate rings of complexes Sa, & and 11

8a SC 11 M = Cr M=W M = Pd M-P-C( 1)---C(2) - 52.5(3) - 54.1(7) 43.5(3) P-C(l)-C(2~(3) 80.3(4) 81.8(10) -71.9(4) C(l)-C(2)---C(3FS -81.1(4) -82.4(10) 67.0(4) C(2)--c(3v-M 57.7(3) 57.6(6) - 34.9(3) C(3)-S-M-P - 28.8(2) - 28.9(4) 6.4(2) S-M-P-X( 1) 25.4(2) 26.0(4) - 9.9(2)

ate rings, as shown in Fig. 4(a). Apparently, the trivalent thioether (coordination to the metal) helps to relieve some 1,3-diaxial interactions in the chelate rings of complexes 8a and &, so that the chelate rings are able to adopt chair forms [Fig. 4(b)].

In contrast to an equatorial position, the phenyl group attached to the sulphur atom is situated in an axial position in the palladium complex 11. This difference obviously suggests the “eclipsed” inter- action of the equatorial phenyl group and the chlor- ide ligand to be larger than the 1,3-diaxial inter- action. Of course, another factor contributing to this outcome is that the larger angle of !S-Pd-P [97.8 l(6)“] increases the distance between phos- phorus and sulphur, which leads to the decrease of the 1,3-diaxial interaction between the phenyl groups.

The resolution of the chiral ligand PSO and its applications are currently in progress.

EXPERIMENTAL

The general information has been described in detail previously. ’ Compound 4 was prepared according to the reported method. 8

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co

Fig. 4. (a) Three types of major steric interactions of (P,S)Mo(CO), in the chair conformation: (i) 1,3-diaxial interactions (---); (ii) “eclipsed” interactions between apical ligands (CO) and phenyl groups (-. -.-) ; (iii) interactions between apical ligands arid axial hydrogen atoms (Z).

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Tripodal ligands with mixed donors 2583 3-Methoxymethyl-3-methyloxetane (5)

Freshly-cut sodium metal (3.7 g) was added to a solution of 4 (16.27 g, 0.16 mol) in toluene (40 cm3). The mixture was heated to reflux overnight. Iodomethane (12 cm3, 0.16 mol) was added to the above solution, which was then stirred at room temperature for 36 h. The reaction mixture was quenched with water (50 cm3) and the organic layer was separated. The organic portion was extracted with ether (20 cm3 x 3). All organic extracts were combined, dried and concentrated. The residue was distilled to give compound 5 (10.0 g, 54%) as a clear liquid : b.p. 138-142”C/760 mm (similar to literature’).

2- Hydroxymethyl-2-phenylthiomethyl- l-methoxy- propane (6)

Freshly-cut sodium metal (4.15 g, 180.4 mmol) was added to ethanol (70 cm’) under a nitrogen atmosphere. After all the sodium had reacted, thiophenol(18 cm3, 175.3 mmol) was added to the ethoxide solution slowly, this was then stirred for 30 min. Compound 5 (6.63 g, 57.2 mmol) was trans- ferred into the above solution and the resulting mixture was heated to reflux overnight. Water (20 cm’) followed by ether (40 cm3) was added to the reaction mixture. The organic layer was separated, and the aqueous layer was extracted with ether

(30 cm3 x 2). The combined organic extracts were dried and concentrated. The residue was chro- matographed on silica (100 g) with elution by 5% ethyl acetate in hexane. The desired compound 6 was obtained as a viscous, yellow liquid (8.08 g, 62%). ‘H NMR: 6 7.40-7.00 (m, 5 H), 3.48 (d, J = 9 Hz, 1 H), 3.42 (d, J = 9 Hz, 1 H), 3.20 (d, J = 3 Hz, 2H), 3.15 (s, 3 H), 3.08 (d, J= 9 Hz, 1 H), 2.92 (d, J = 9 Hz, 1 H), 2.70 (br, 1 H), 0.80 (s, 3H).Found:C,63.1;H,8.1.Calc.forC,ZH,802S: C, 63.7; H, 8.1%. 2-Diphenylphosphinomethyl-2-phenylthio- 1 -meth- oxypropane (3)

The hydroxy compound 6 was transformed into mesylate 7 according to a standard procedure described previously. lb To a solution of diphenyl- phosphine (3.23 g, 17.2 mmol) in THF (100 cm3) was added a 2.50 M hexane solution of n-butyl- lithium (17.0 cm3) at ice-cooled temperature. After stirring for 30 min, compound 7 (4.24 g, 13.9 mmol), in a small portion of THF, was added to the phos- phide anion solution. The resulting mixture was heated to reflux for 4 h ; degassed water (10 cm’) was then added. The organic layer was separated, dried and concentrated. The crude product was chromatographed on silica (100 g) with elution by 40% ethyl acetate in hexane. The desired tripodal ligand, PSO, was obtained as a viscous, colourless

Table 4. Summary of crystal data of complexes 8a, 8c and 11

Formula Crystal size (mm) Lattice Space group a (A) b (A) c (A) V(A3) Z F(OO0) Temperature (K) p (mm- ‘) Transmission 2&n,, k k 1 1 (‘Q Number of reflections

Number of observed reflections Number of variables R(F) UF) S 8a CrPSCZsHZ70, 0.7 x 0.7 x 0.5 Orthorhombic Pna2, 16.786(8) 12.728(g) 12.754(4) 2725.1 4 1088 300 0.57 0.94-1.0 54 21, 16, 16 0.7093 3097 2208 (> 2.5~) 325 0.045 0.034 2.42 0.6 x 0.6 x 0.5 Orthorhombic Pna2, 16.896(8) 12.768(4) 12.837(5) 2769.3 4 1240 300 4.42 0.65-1.0 55 21, 16, 16 0.7093 3318 2477 (> 2.00) 325 0.040 0.037 3.81 11 PdPSCz4Hz3Cl,0 0.5 x 0.5 x 0.5 Orthorhombic Pbca 16.223(3) 15.447(3) 19.737(3) 4945.7 8 2064 300 1.11 0.85-1.0 50 19, 18, 23 0.7093 4350 2682 (> 2.5~) 270 0.037 0.037 2.87

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H), 3.00 (s, 3 H), 2.90 (s, 2 H), 2.20 (d, .&--c--H = 3 Hz. 2 HJ,. 0 .‘Xl {s. 3 KJ_ Found : C. 73 1 I ; H,. 7-0. Calc. for CZ4HZ70PS : C, 73.1 ; H, 6.9%.

Preparation of 8a-8c

The ligand PSO and an equimolar amount of group VI metal carbony’l t,lVif,CX$, M = Cr, MO and W) Were &ss&& in an ar ornat% s&+eBL {$&- ene or xylene) anb hear& 10 r&w for $-ID h,

Tfie absiredcompl’exes were isoiated 6y cdromatog-

ra_uQ on siitca. All s~oecctroscopic and ana&v~tc data are given in Table 1.

Preparation of (PSO)Mn(CO),Br (9)

A solution of BrMn(CO), (45.7 mg, 0.17 mmol) and PSO (65.5 mg, 0.17 mmo1) in cb~oroform was refluxed For 30 min. After addition of hexane, the solution was allowed to stand for several days. The complex fac-(PSO)Mn(CO)3Br was crystallized as yellowish needles (65.3 mg, 64%). IR : v(W) 2034,1961,1907 cm-‘. ‘H NMR: 6 7.90-7.30 (m, 15 H), 3.25 (s, 3 H), 3.09 (d, J = 8.84 Hz, 1 H), 3.03 (d, J= 8.84Hz, 1 H),2.71 (d, J= 11 Hz, 1 H),2.64 (d, J = 11 Hz, 1 H), 2.44 (dd, J = 10, 15.3 Hz, 1 H), 2.15 (dd, J = 10, 15.3 Hz, 1 H), 0.61 (s, 3H). 3AP NMR: 6 25.66. Found: C, 48.7; H, 4.0. Calc. for C2,H,,0,PSMnBr: C, 49.1; H, 4.1%.

Preparation of (PSO)PdC12 (11)

This complex was obtained as a yellow, crys- talline solid by stirring a mixture of PSO and PdCl, in acetonitrile, followed by recrystallization from dichloromethane and ethyl acetate, m.p. (dec.) 190°C. ‘H NMR: 6 7.947.30 (m, 15 H), 3.03 (s, 3 H), 2.97 (d, J = 5 Hz, 1 H), 2.95 (d, J = 5 Hz, 1 H), 2.89 (d, J = 2.7 Hz, 1 H), 2.87 (d, J = 2.7 Hz, 1 H), 2.49 (dd, J = 22.5, 12 Hz, 1 H), 2.09 (dd, J = 22.5, 12 Hz, 1 H), 0.93 (s, 3 H). 31P NMR: 6 17.81. SPdCl,: C, 50.4; H, 4.8%.

Crystallographic analysis of complexes Sa, 8c and

11

Cell parameters were determined on a CAD-4 diffractometer by a least-squares treatment. Atomic scattering factors wee taken from the International TW& fk Z+q G=jwii&&iwj&-f: ’ O Compctatiun was carried out by using tne &KK SiX? V&X package. ‘I Re&vanL &a. are sunma m_ Tade 4.

Acknowledgement-Financial support from the National Science Council (R.O.C.) is acknowledged.

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. REFERENCES

(a) S.-T. Liu, H.-E. Wang, M.-C. Cheng and S.-M. Peng, J. Organomet. Chem. 1989, 376, 333 ; (b) S.-T. Liu, G.-J. Liu, C.-H. Yieh, M.-C. Cheng and S.-M. Peng, J. Organomet. Chem. 1990, 387,

83; (c) S.-T. Liu, C.-H. Yieh and H.-J. Lu, Phos- phorus, Sufjii and Silkon 1989,44,X1.

S. G. Murray and F. R. Hartley, Chem. Rev. 1981, 81, 365 and refs therein.

For recent review in tripodal polyphosphines see : L. Sacconi and F. Mani, in Transition Metal Chemistry (Edited by G. A. Melson and B. N. Figgis), Vol. 8, p. 179. Marcel Dekker, New York (1982).

M. F. Lappert, D. B. Shaw and G. M. McLaughlin,

J. Chem. Sot., Dalton Trans. 1979,427.

C. S. Kraihanzel, J. M. Ressner and G. M. Gray, Znorg. Chem. 1982, 21, 879.

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數據

Table  1. Spectroscopic and analytical data  of complexes  8a-8c

Table 1.

Spectroscopic and analytical data of complexes 8a-8c p.2
Fig. 2. The ORTEP drawing of  8a  (ph&yl  groups omitted
Fig. 2. The ORTEP drawing of 8a (ph&yl groups omitted p.3
Fig.  1. The ORTEP  drawing of 8e.
Fig. 1. The ORTEP drawing of 8e. p.3
Table 2. Selected  bond  distances  (A)  and  bond  angles  (“)  of complexes  8a, 8c  and  11

Table 2.

Selected bond distances (A) and bond angles (“) of complexes 8a, 8c and 11 p.3
Table  3. Torsional  angles (“) around  the  six-membered  chelate  rings  of complexes  Sa, &  and  11

Table 3.

Torsional angles (“) around the six-membered chelate rings of complexes Sa, & and 11 p.4
Fig. 3. ORTEP  drawing of complex  11.
Fig. 3. ORTEP drawing of complex 11. p.4
Table  4.  Summary  of crystal  data  of complexes  8a,  8c  and  11

Table 4.

Summary of crystal data of complexes 8a, 8c and 11 p.5

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