Complexes of osmium with polytertiary phosphines

J. mo~. m~. C/~m. Vol. 42. pp. 547-549 Pmlplmon Press Ltd.. 1950. Printed in Great Britain

COMPLEXES OF OSMIUM WITH POLYTERTIARY PHOSPHINES M. M. TAQUI KHAN, S. SHAREEF AHAMADand MEHREEN AHMED Contribution from the Deparlment of Chemistry, Nizam College,Hyderabad 500 001, India

(l~rst received 22 November 1977; in revi~ed/orm 25 April 1979) Almatract---Complexesof Osmium(II)and Osmium(Ill)with the polytertiary phosphines,CsHsP[CH2CH2P(Cd'Ish]2; (triphos), (Cd'Is)2PCH2CH~P(C.sHs)CH~H2P(CsHs)CH~CH2P(Cd'Ish(tt~raphos-I), P[CH:CH=P(Cd'I~hh: (tetraphos-2) and CJ'Is{CH2P[CH~H=P(CsHsh]zh; (TDDX) are desc'n'i~l. Osmium trichloride reacts with triphos, tetrapbos-l, and tetrapbos.2 in benzene methanol mixture at reflux temlmature to give the complexes OsCI~ (tripbos), [OSO3(S)h (tetraphos-l) and OsCi3(tetraphos-2)respectively.The hexatertiary phosphine TDDX, formed only polynuclear complexes with osmium and attempts to prepare mononuclear complexes failed. The ligand TDDX reacted with either osmium uichimide or ammonium hexachioro osmate(IV)in boilingethanol to give the diamagnetictrinuclear complexOs~CIsCrDDX)and parumagneticcomplexesof the type Os2X~CI'DDX)where X = CI or Br). The proton NIvlR spectra of the complexes are discussed and used along with the IR data to assign configurations. All reactions were carried out in an oxygen free nitrogen atmosphere by passing the gas through vanadinngll) sulphate solution and finally through ascarite. All solvents were purged with purified nitrogen prior to their use. Magne~ sugeptibility were made on a Faraday Balance at 30°C. [CHg:H,P{G2hhh(triphos), (C,,HshPCH2CH~- measmcments Synthesis of complexes. Complexes 1-3 of Table I P(CffIs)-CH~H2P(CffIs)CH2CHz-P(CffI~h(tetraphos-l) were synthesized by a general synthetic scheme that involvesthe and P|CH2CHJ~(C~Hs)-As(t~raphos-2) were first syn- addition of 0.50mmol of osmium trichloride hydrate to about thesixed by King and Kapoor[4] and their complexes 30 ml of methlmol.To the green solufon was add~ 0.50mmol of with several metal ions have been reported[5]. The triphos, 0.50 mmoi of tetrapbos-I or 030mmol of tmapims-2 in isomeric iigands tetraphos-I and tetraphos-2 contain 30 mi of benzene and the solution,was heated for 5 hr at reflux temperature. The solution turned brown for tr:¢~os, dark brown respectively linear P-P-P-P and tripod P-P3 ananpment of the donor phosphorous atoms. King a aL[6] have also for tetraphos.l and dark red for tctraphos.2. The solution in all studied the prepamtiun and complexes of the hex- cases were reduced to small volume (5-1Oral) in vacuum and atertiary phosphin¢, l,l,4,4-tetrakis (2-diphenyl phos- addition of a few mi of petroleum ether precipitated the products. The compounds OSO3 (Uipbos) [osO3(Shl{tctraphosphino ethyl)-l,4-diphospha butane (hexaphos) which is I) and O s ~ t e t r ~ . 2 ) were collected by fdtration, washed analogous to EDTA in the relative disposition of its with metinmoland dried. donor atoms. Taqui Khan and Martell[7] synthesized the Cav/mny/tA~,ou~z'/dovoonn/am(//).A solution of osmium hexatertiary phosphine, P, P, P', P'-tetrakis(2-diphenyi trichloride hydrate (0,15g, 0.50ml) in 30ml of dimetbyfforphosphinoethyl) a,a'-~nospha-p-xylene O'DDX) and a mamide (DMF) was rehexed with 03 g (036 mmol)of triphos for green color of the solution champd to orange number of complexes with different transition metal ions 10hr. The ~ have been reported. These polytertiary phosphines not and the addition of a few drops of hydrochiorica¢~ lncipated a only provide stereochemistries and reactivity ~ s on pale yellow compound. The compound was fiRered and recrystalliznd from methanol. the metal ion, that are not otherwise poss~le with cor~-Tetrapho$-I bis(dicldomdicarbonylosmhmXll).A mixture responding monodmmm phosphines, but their metal of ~ (0~g, 0.50retool) in 50nd of DMF, 10mi of complexes also afford the possibility of acting as poly- water and tetraphos-I (0.3g, 0.46mmot) was rduxed for 9 hr. functional catalysts. Hence a study of the octahedral d s Tne color of the ~ clumpd from yellow to iisht green. The and d ~ complexes of osmium(III) and osmium(II) with solution was cooled overnight. A part of the solution was triphos, tetraphos-l, tetraphos-2 and TDDX have been evaporated under reduced pressure. On the addition of few drops of hydrochloric acid, a green solid was precipitated. The cominvest~ated. pound was washed with methanol,benzene and dried. #- Tetmphos.2 bis(dichlovodicavbonylosimamXll). A solution of osmium trichloride (0.13g, 0.48mmol) in 30ml of DMF was EXPERllVlmqTAL re0uxed with 0.25g (0.45retool) of tetrapbos-2 for 10hr. The Materials. The iigands tripbos, tetraphos-I and tetraphos-2 initial green color of the solution changed to yellow and the were purchased from Pressure ChemicalCorp. Inc. (U.S.A.).The addition of a few drops of h~droch]oricacid precipitateda brown ligand TDDX was synthesized by published procedure[TJ. Am- compound. The compound was collected by filtration washed moniumhexahaloosmat¢{IV) was prepared by the method of with methanol and dried. Dwyer and Hogarth{S]. The hydrated osmitm~IIl) chloride was ~¢-TDDX-lmmcldoratriosmiam(ll). To a solution of osmium obtained from AIh lnmlpmics.Microanalyseswere performedby richloride hydrate (0.3g, ! retool)in 30 ml of ethanol, was added AusUalianMicmamlytical Service, C$1RO, Australia. IR spectra a solution of TDDX (0.7g, 0.70retool) in 25 ml of ethanol. The in KBr pallets were recorded on a Perkin-Elmmr-257IR spectra above solution was refluxed for 17hr. The inilinlgreen color of far-IR in Nujoi mull with a B¢ckmann IR-12 spectrophotometor. the solution changed to brown. The solution was cooled when a The NMR spectra of the solution of the samples in deuterated brown compound p r o r a t e d . The solid was washed with henchloroform were recorded with a Varian A-60-D Spectrometer. zene aad recrystallizedfrom petroleum ether. The conductivity naamutemeuts were done in dim¢,hyl #-TDDX-~(M). A'mixtore of 0.41g of acetamide solutions at 30°C with an Elico conductivity bridge. (NI'hhOsCl6 in 25 ml of concentrated hydrochlori~ acid and ~

N

During the last few years metal complexes of various chelating polyteritary phosphines[l-3] have been extensively studied. The iisands C.d'IsP-

547

548

M.M. TAQUI KHAN et at Table 1. Elemental analysis m.ps. and conductivity data of Os(II) and Os(HI) complexes of polytertiary phosphines m.p. (°C)

Carbon (%)

Hydrogen (%)

Phosphorous (%)

Chlorine (%)

Conductivity (M-' cm2ohm-t)

10sCl3(triphos)

272-275d

30sCl3tetraphos-2

260-265d

40sCI2(CO)triphos

220-224d

11.8 (12.8) 14.5 (15.0) 10.8 ( ! 1.02) --

I0.16

252-254d

5 [OsCI2(CO)2]2tetraphos-2

271-273d

--

7.05

6 [OsCIz(CO)2Jztetraphos-1

243-245d

4.0 (4.0) 3.85 (3.8) 4.5 (4.3) 3.8 (4.0) 3.3 (3.2) 3.3 (3.2) 3.6 (3,6) 4.1 (4.0) 3.2 (3,1)

--

2 [OsCI3(S)]2tetraphos-I

49.0 (49.1) 45.8 (45.65) 52.1 (52.14) 50.8 (51.0) 42.1 • (42.2) 42.1 (42.2) 42.5 (42.7) 47.7 (47.7) 37.3 (37.2)

--

6.11

--

--

13.4 (13.2) ~

--

Compound

70s3CidTDDX)*

> 300

80s:,CIdTDDX)*

>300

90szBrdTDDX)*

> 300

--11.1 (11.3) 9.6 (9.5) 9.6 (9.5) 10.2 (10.3) 11.5 (11.5) ~

9.01 9.38 9.23

Calculated values in parenthesis, d = with decomposition. S = solvent. *Conductivities could not be determined due to the extremely low solubility of the complexes. 40 mi of ethanol was reflexed for 7 hr. The solution was then evaporated under pressure. A yellow solid was obtained, which was filtered, washed with ethanol and recrystallized from benzene.

#-TDDX-~xubromodiosmim(lll). To a solution of TDDX (0.3g, 0.30mmol) was added a solution of (NI-G)zOsBr6(0.1 g, 0.15 mmol) in 30 ml of ethanol and 10 ml of water. The solution was reflexed for 6 hr. A black precipitate was obtained which was washed with ethanol, benzene and dried. RlgSULTSAND DISCUSSION Table ! gives the analysis, m.p. and conductivity measurements on the above complexes. The IR spectra and the NMR spectra are given in Table 2. Conductivity data on complexes 1-6 in DMA are presented in Table I. The conductivities are all very low indicating that the complexes are nonelectrolytes[9]. Reaction of osmium trichloride with the polytertiary phosphines triphos, tetraphos-I and tetraphos-2 in boiling methanol-benzene mixture and precipitation of the complexes by petroleum ether afford the most convenient complexes of osmium(III). The complex OsCl3(triphos) 1 shows a single I, M-CI peak at 324cm-' indicative of facial halogens. The NMR spectrum shows

a singlet for phenyl protons at 2.65 ~" and methylene multiplet at 7.0 ~'. In the IR spectrum of 2 a single peak corresponding to an M-CI stretch appeared at 324cm-' which shows that the halogens in this complex are also coordinated in a facial manner. The NMR spectrum of the compound gives a phenyi multiplet centred at 3.50 ~and a methylene multiplet centred at 8.1 ~-. Complex 3 gives a broad ~ M-CI peak at 312cm-* suggesting that the halogens in this complex are meridoniaL However, it was not possible to assign one more band expected for a met-configuration due to broad nature of the 312cm-: band. The NMR spectrum of the compound shows a phenyl doublet at 2.7 ~"and singlets at 8.8 and 9.2 r in ratio of I:2 corresponding to free and coordinated methylene protons, respectively. In this complex, tetraphos-2 must he coordinated as a terdentate ligend, the remaining coordination positions on the metal ion being occupied by the three chlorines. All the osmium(liD complexes 12,3 show a magnetic moment corresponding to one electron. Complexes 4 and S were obtained directly by refluxing OsCI3.nH,O with triphos and tetraphos-2, respectively in dimethyl formamide and 6 with (NI-L)-zOsCls and tetraphos-I in dimethyl formamide. The IR spectrum of 4

Table 2. IR Spectra and proton N/v~ sp~tra of Os(II) and Os(III) complexes of p o l y t ~

phosphines

Chemical shifts Compound

:,(M-X) cm-:

10sCI3(triphos) 2 [OsCI3(S)htetraphos-I 30sCl3tetraphos-2 40sCi2(CO)triphos 5 [OsCl~CO).~tetraphos-2 6 [OsCl~(CO)z]2tetraphos-1 70s3CI,(TDDX) 80s2CIdTDDX) 90s2BrdTDDX)

324 324 312 300,285 310,300,180 300 295 325,300,280 227

v(C=O)cm-' ---1950(st) 1930(st) 1930(st),2000(md) ----

phenyl protons

methylene protons

2.65(s) 3.50(m) 2.7(d) 2.6(s) 2.5(s) 2.6(s) 2.5(m) 2.5(m) --

7.0(m) 8.1(m) 8.8(s), 9.2(s) 7.35(0 7.35(t),7.9(t) 5.45(s),7.25(t),8.0(s) 5.8(d),6.6-.6.8(brjn) 5.8(d),6.6--6.8(br,m) --

Key: t = triplet, d = doublet, s = singlet, m = mulfiplet, br = broad, st = strong, md= medium, S = solvent. X=CI or Br.

Complexes of osmium with polytertiary phosphines shows a band at 300cm -~ with a shoulder at 285cm-' corresponding to Os-C! stretching frequencies. The two chlorides in the complex are thus cis to each other. The band at 525 cm-' tentatively assigned to the metal-phosphorous stretching frequency. The ~,(C=O) was observed at 1950 cm-'. The NMR spectrum of 4 shows a singlet at 2.6 ~ and a triplet centred at 7.35 ~ corresponding to aromatic and methylene protons, respectively. Treatment of the complex with carbon monoxide resulted in the formation of a cis dicarhonyl by the displacement of one of the coordinated phosphine groups of triphos by CO. The formation of a cis dicarhonyl was indicated by the appearance of another peak of medium intensity at 2000cm-' in the IR spectrum of the compound. The polynnclear compounds $ and 6 do not contain any bridging carbonyls as indicated by the absence of peaks around 1800cm -I characteristic of bri~'ng carbonyis. IR spectral data for $ clearly show that the halogens are mutually trans and the carbonyl groups cis t o each other. The NMR spectrum shows a phenyl singlet at 2.5 ¢ and methylene triplets at 7.35 and 7.9 ¢. The peaks at 7.35 and 7.9 ¢ indicate the presence of bridging and non-bridging methylene protons. The IR spectral data for 6 clearly show that the chlorines are cis (peaks at 300and 280cm -I) and the carbonyl groups are trans (a single peak at 1930cm-*). The NMR spectnan of the compound shows a single peak for the phenyl protons at ~---2.6 and three peaks for the methylene protons at ¢ = 5.45, 7.25 and 8.1). The peak at ~ = 5.45 can be assigned to the bridging methylene protons and the other at ¢ = 7.25 and 8.0 to nonbridging methlyeue protons, further split by the bridging methylene protons. Reaction of osmiumtrichloride or ammoniumhexahaloosmate(IV) with TDDX in boiling ethanol gave the diamagnetic trinuclear complex 7 and the binuclear complexes $ and 9, p,~ = 1.946 and 1.7 B.M. respectively. Simple 1:1 mononuclear derivatives of Os(II) and Os0H) with TDDX could not be obtained even when the reaction was conducted in a 1 : 1 ratio of o

0

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m

~

c

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I

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l,........... ~::-.--'P~ ..""~ f.." ---~.~ ........ -. +~................ i~. .'>cI

...c.~. :

- D ~

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.

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549

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\-/ .................',..........~"

' , ..............

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/ P C ........ ....................

"hA--'...-"/ CI [OsCl2(CO~ tetrOI)hos-2

Fig. 2. Os2CI6(TDDX). reactants. This shows the preference of TDDX to form polynuclear complexes as compared to mononuclear species. Taqui Khan and Martell[7] have reported the complex Ir,CidTDDX) in which the ligend TDDX coordinates to only two of the three iridium atoms. A similar possibility may be considered in the case of Os,CIdTDDX) 7 (F~g. 1). The metal halogen stretching frequency is observed as a single band at 295 cm -~, corresponding to the bridging halogens in this complex. In complex 8 (Fig. 2) the bands at 325, 300 and 280cm-' correspond to a meridonial anangement of the coordinated haloges. A broad band due to ~, (Os-Br) is observed at 227 cm - ' in 9. The NMR spectra of 7 and 8 show a complex asymmetric phenyl proton resonance at •---2.5. A donbier due to the p-xylene methylene protons is observed at ~-= 5.8 and a multiplet due to methylene protons from ~-= 6.6-6.8. The presence of too many phenyl groups in the molecule makes the solubility of the complexes very low in common organic solvents. For this reason it was not possible to carry out datailed NMR studies and conductivity measurements.

~ E S I R. B. King, R. N. Kapoor, M. S. Santo and P. N. Kapoor, Inorg. Chem. le, 1851 (1971). 2. W. O. Siegl,S. J. Lapporte and J. P. Collman, Inorg.Chem. I0,

2158 (1971). 3. J. C. Cloyd and D. W. Meek, lmorg. Chim. Acta 6, 607 (1972). 4. R. B. King and P. N. Kapoor, J. Am. Chem. Soc. 93, 4158 (1971). 5. "1L B. King, P. N. Kapoor and R. N. Kapoor, lnorg. Chem. 10, 1841 (1971); bM. M. Taqui Khan and A. E. Marteil, lnorg. Chem. 13, 2961 (1974). 6. R. B. Ki~ and M. S. Saran, lno~. Chent lO, 1861(1971). 7. M. M. Taqui Khan and A. E. Martell, lnorg. Chem. 14, 676 (1975). 8. F. P. Dwycr and J. W. Hogarth, Inorg. SyntlL S, 204 (1957). 9. W. J. Greary, Coord. C/u~n. Rev. 7, 81 (1971).