Journalof’theKorean ChemicalSociey 2000, vol. 44, No. 4
Prkd in the Republicof Korea
tmns-[FeH(NCS(Me) -S)(dppe)2]I ~%}-~
#rans-[Fe(NCS)JPh,P(0)CH2CH2P(O)PhJ,][I,E &tq
3%s%34 “ *JRE4*
‘%3-%+%-=x}%+%-+- ww-
(2000.7.7 ~d+)
Oxidation of trans-[FeH(NCS(Me)-S) (dppe)2]I to
trans-[Fe(NCS),(Ph,P(0)CH,CH,P(O)PhJ,][L] (dppe = PPh,CH,CH,PPh,)
Ji Hwa Lee and Soon W. Lee*
Department of Chemistry, Sungkyunhxzm Univer.siry Natural Science Campus, Suwon 440-746, Korea (Received July 7, 2000)
ABSTRACT. The Fe(fI)-isothiocyanato complex war@FeH(NCS)(dppe),] (1) reacted with iodomethane (Mel) to give methyl isothiocyanide-Fe(II) complex, tr-an,s-~eH(NCS( Me)-S)(dppe),jl (2). Compound 2 was oxidized to trans-[Fe(NCS)*(PhZP(O )CHjCH#(O)Ph&][Ij] (3 ), which was structurally characterized by X-my diffraction. The molecuku structure of 3 showed a bent Fe-NCS group, Crystallographic data for 3: rnclinic space group Pi, a=l 1.071(2) ~, b=12.054(2) ~, c=l 2.121 (1) & a=lO1.02(1~, ~=95.887(9~, ~1 10.34(1~, Z=
1, R(wR,)=O.0567(0. 1294).
INTRODUCTION
Tmnsition-metalisothiccyanato (M-NCS) complexes have got continuous attraction.’”” In particular, these have pro- vided an extensive series of examples of linkage isom- erism (N- or S-bonded NCS). We have become interested in the nucleophilic properties of the YCS stdtirr atom and recently reported the preparation and structure of h-ans-[FeH(NCS(i-Pr)S)(dppe)~] [1] (dppe=PPhjCH,CH,- PPhJ, which has been prepared by the electrophilic attack of the mild electrophile i-l%t at the NCS sulfur atom (eq 1).’2
Because of our continuous interest in investigating the nucleophilicity of the NCS sulfur atom in the neutral Fe (11)-NCS complexes. we set out the reaction of the trans- [FeH(NCS)(dppe),l with mother electrophile, iodome- thane (MeI). Here we report the synthesis and charac- terization of rrans-[FeH(NCS(Me)-,S)(dppe)Z]I (2). We also repfi the molecular sbucture of zrans-~e(NCS)@hzP(0)- CHZCHjP(0)Ph&][IJ (3), which was formed by the oxi- dation of 2.
s i ‘x ”
EXPERIMENTAL SECTION
Unless otherwise stated, all reactions have been per- formed with standard Schlenk line and cannula tech- niques under argon. Air-sensitive solids were manipulat- ed in a glove box filled with argon. Glassware was soaked in KOH-saturated 2-propanol for about 24 h and washed with distilled water and acetone before use, and it was either flame-dried or oven-dried. Diethyl ether (Et,O) was distilled over sodium metal under argon.
Dichlorometharw was stirred over CaH, and distilled by vacuum trmsfer. The NMR solvent (CDCIJ was degms- ed by freeze-pump-thaw cycles before use and stored over molecular sieves under argon. Iodomethane (CHJ)
–311-
was purchased from Aldrich company. Compound trans- IFeH(NCS)(dppe)J (1) was prepared by treating trmr- [FeHCl(dppe), ] with KSCN.
‘H- and “C{ ‘H ]-NMR spectra were recorded with a Varian Unity Inova 500 MHz spectrometer with refere- nce to internal solvent resonances and reported relative m tetramcthylsikine. ~JP-NMR spectra were also recorded with a Varian Unity Inow 500 MHz spectrometer with reference to extermd 85% H,PO,. Ill spectra were re- corded with a Ylcolet 205 FTIR spectmphotomcter.
Melting points were measured with a Thomas Hoover capihy melting point apparatus without calibration.
Preparation of tram-[FeH(NfXMe)( dppe),]I, (2).
Compound 1 (0.137 g, 0.015 mmol ) was dissolved in 1 mL of icdometbane. and the solution was stirred for 1 h. During stirring, a red slurry turned to a yellow one.
The resuhing solution WM filtered. and the remaining solid w~s washed with EtXl (31 O mL) and then dried under vacuum to give ().132 g (0. 125 mmol, 84’%) of 2
‘H-NMR (CDCI,): 37.388-6.760 (40H, m, J%PCH,- CH,PPh,), 2.614 (3H. s, NCSCHJ, 2.581 (4H, broad, Ph,PCH2CHlPPhJ, 2.079 (4H, broad, Ph,PCH*CH?- Pph2), 19.904( lH. quintet, 2J,.H=47 Hz. H-Fc). “C{ ‘H}- N.MR (CDCL): 8135.840, 134.627, i34.153> 133.686.
133.158, 130.658.129.523, 129.263, 128.479, 1287.819 (phenyl ), 118.940 (NCSCH;), 33.49 I (Ph,PCFLCH~pphJ
18.324 (NCSCHJ. ~‘P-NMR (CDCIJ: 684.020” (d, ‘.IP.+
=47 Hz). mp (dec.): 168-170 “C. H? (KM-): 2122 (N~C), 1871 (Fe-H) cm ‘.
~OITIliltiWl of tis-FdNGk]~MO)C~z~HX(0)-
PM[L], (3). When the recrystallization of’ compound 2 ti-om CH,Cl&O was tried, it transformed to trrm- [Fe(NCS),PhjP(0)CH,CH,P(O)Ph,][I,], (3). IR (KBr):
2030 (NC), 1127, 1150 (P=O) cm-’.mp (dcc.): 108-1IO”C.
X-ray Structure Determination of 3. All X-ray data were collected with usc of a Siemens P4 ditliactometer equipped with a Mo X-ray tube and it graphite crystal monochrornator. The orientation matrix and unit cell parameters were determined by least-squmes analyses of the setting angles of 26 reflections in the range 15.W6
<~5.00. IIWX check reelections were measured every 100 reflections throughout data collection and showed no significant variations in intensity. Intensity data were corrected for Lorcnz and polarization effects. Decay cor- rections were also made. The intensity data were empir-
Yitile 1.X-rav data collection and structure refinement for 3 formula
Sw
temperature, K crystal system space group 0, A b. ~ c, A CLdeg
~, deg y, deg K A3 z d,,,,,gcm-’
m, rnn-’
T“,,.
T?!,,, F(OOO)
No.of reflections measured No. of reflections unique Xo. of reflections wi[h I>2cJ(I) Xo. of parameters rctinccl XI range f’)
scan type scan speed
G(JF (goodness-of-fit on F’) Max., min. in Ap (e ~) R
WRZ”
CJL&O,P,SJ,Fe 1413.49 296(2) triclinic PI
I I.07 i (2) 12.054(2) 12.121(1) I 01 .02( 1) 95.X87(9) 1 10.34(I) 1584.4(7)
J
1.(W2 4.032 ().5()46 0.6199 695 5184 4904 4183 320 3.5-50.0 m variable
1.035 0.823,-1.019 0.0567 0.1294
ically corrected with v-scan data. All calculations were carried out with use of the SHELXTL programs.: 1
A red crystal of 3, shaped as a plate of approximate dimensions 0.78x 0.30X 0.08 tnd, was used for crystal and intensity data collection. Details on cryxtal data and intensity data are given in Table J. The unit cell param- eters indicated the triclinic unit cell with the two possible space groups: Pi and P1. A statistical analysis of reflec- tion intensities suggested a ccntrosyrnmetric space group, and the structure [malysis converged only in Pi. The structure was solved by the direct method and refined by full-matrix least-squares calculations of F2. initially with isotropic and finally anisotropic temperature factors for all non-hydrogen atoms. All the other hydrogen atoms were generated in idealized positions and refined in a
Jourmzl(?fthe Korean ChemicalSoccie(y
Tdle 2. Atomic coordinates( ~ 10? and equivaknl iwtmpic dis- placement prarnctcrs (E x 1O’)for 3
x y z U(eq~
Fe(1) s(l) l?(l) P(2) 0(1) 0(2) N(l) c(l) C(2) C(3) q’!) C(5) C(6) c(7) C(8) C(9) C(10) C(n) C(12) c(13) C(14) C(15) C(16) C(17) C(18) C(19) C(20) C(21) C(22) C(23) C(24) C(25) C(26) C(27) l(l) 1(2)
3UUU –W(XJ
1760(2)–7955(2) 3554(1) –6705(1) 3410(1)–3175(1) 3722(3)–4204(3) 3814(3)–5895(3) 3959(4)–6361(4) z2w(4) –81144)
1395(5)–8211(5) 357(5)–9312(5) 125(5) 10276(6) 915(5) 10202(5) 1976(5) 9119(4) 3198(4) 5969(4) 3793(8) 4754(6) 3494(Io) 4166(7) 2666(7) 4775(7) 2048(9) 6003(7) 2305(8) 6589(6) 1986(4) 3753(4) 1219(5) 4994(5) [33(6) 5449{7) 206(6) 4716(8) 528(7) 3503(7) 1649(6) 3000(5) 3167(4) 2241(4) 2445(9) 1519(7) 2297(II) 805(8) 2846(7) 794(8) 3468(11) 1562(14) 3618(10)2301(11)
4936(4) 7095(4) 4718(4) 2201(4) 3052(5) 7025(4) 3576(l) 832(I)
5000 0
6229(2) 2316(1) 5960(1) 5327(3) 3487(2) 5683(4) 2168(4) 2979(4) 2864(5) 1983(5) 1188(5) ]27~{4) 1246(4) 1422(6) 582(8) 356(6) 559(6) 249(5) 6580(4) 6244(5) 6737(7) 7518(8) 7866(6) 7412(5) 5048(4) 5275(6) 4562(7) 3634(8) 3347(10) 4069(8) 2034(3) 7119(4) 5924(4) 8393(I)
1oOoo
LX(1)
86(1) 32(I) 34(1) 44(1) 43(I)N(l )
55(1) 38(1) 52(1) 67(2) 68(2) 61(1) 49( 1) 41(1) 100(3) 129(4) 84(2) 103(3) 82(2) 40(1) 58(1) 84(2) 89(2) 82(2) 61(1) 45( 1) 96(3) 112(3) 1CO(3) 182(7) 140(5) 35( I) 37( 1) 47( 1) 87( 1) 88( 1)
‘Equivalent isotropic U defined as one third of the tmce of the orthogonalizcd U,,tensor.
riding model.
Final atomic positional parameters are shown in Xzble 2. Selected bond distances and bond angles for 3 is shown in Table 3.
2000>vol. 44,,’V O.4
FULSULTS AND DISCUSSION
Preparation. An Fe(II)-organic isothiayanide plex, man.r-[FeH(NCS(Me)-S) (dppc)~l[ [] (2), has
313
com- been prepared by the ekctrophilic attack of iodomethane (MeI) at the isodtkxyanato sulfur in a neutral Fe(II)- isothioqrmato (Fe-NCS) complex, o-ans-[FeH(NCS)- (dppe):l (1), (q 2). Stirring the iodomethane solution containing 1 at room temperature for 1 h gives the desired product in high yield (84%). In this reaction, the iodome- thane behaves both as a reagent and as a solvent. Com- pound 2 is stable in rhe solid state, tntt unstabie in solution.
Compound 2 has been chmacterized by NMR (’H-,
‘~C{‘H]-, and “P-NMR) and JR spectroscopy. In the ‘H- NMR spectra of 2, isothiocyanide methyl protons (NCS- CHJ appear as a singlet at 82.614 ppm, and the hydride ligartd as a quintet (6 – 19.904 ppm) beeause of its cou- pling (~./~.H=47Hz) with the four equivalent phosphorus nuclei in the dppe ligands. As expected, the 3’P-NMR spectra exhibit a doublet (b 84.020 ppm) for the dppe phosphorus nuclei with a coupling constant of c./p.II=47 Hz. These NMR data confirm the structure of 2, in which the hydride and the methyl isothiocyanide Iigarrds are tram to each other in axial the sites and the two dppe ligands occupy the equatorial sites. la the 3C{’H]-NMR spectra, the isothkxyanide methyl carbon (NCS-CH;) appears at 818.324 ppm and the NCS carbon at 5118,940 ppm. In addition, the Fe-H and NC bands appear at 1871 and 2122 cm-’, respectively,
The compound 2 in solution seems to be ai-sensitive.
During the crystal growth of 2, it transformed to mans- [Fe(NCS)@h:P(0)CH*CH,P(O)PhA]D,] (3), probably txxause of air-oxidation (eq 3). However, we cannot rule out the possibility that the trace amount of water, present in the cx-ystallimtion solvent mixture (CHjClj-EtZO), reacts with 2 to give 3. In this transformation, the Fe metal for- mally oxidized tiom +2 to +3. the counterion 1 from –1 to – 1/3. and ~he dppe ligands to the corresponding phos- phine oxides (Ph2P(0)CH,CH*P(O)PPh~).
Table 3.Selected bond distances
(A)and
bond angles (“)in 3Fel-N I ~J3q7(4) Fel-01 1.999(3) Fel-02 2.005(3)
pl-o~ !.496(3) p~.o I 1.496(3) PI-C25 1.798(4)
P2-C26 1.794(4) NI -C27 1.151(6) 07-s 1 1.611(5)
11-12 2.917(6)
OJ-Fel -02 87.0(1) 01-Fel-Nl 88.6(2\ 02-Fel -N 1 !?9.0(2)
Fel-Nl-C27 157.6(4) N 1-C27-S 1 178.4[4) P1-02-tkl 150.1(2’)
P2-01-Fel 150.4(2) 01 -P2-C26 11.5(2) 02-PI-C25 111.8(2)
s
(3)
‘- CH3 2 s
3
AS expected from the formal oxidation slate of Fes+
(df). the compound 3 does not show NMR spectm prob- ably because of its pararnagnetk nature. In the El spectra of compound 3, the Fe-H band has disappeared, and the two new P=O bands appear at 1127 and 1150 cm-’.The NC band has a strong intensity at 2030 cm-’. which has shifted to the lower frequency by 91 cm-’ with respect to that in the compound 3.
Structure. The structure of 3 with the atomic num- bering scheme is shown in Fig. 1. The coordination sphere of the Fe metal can be described as an octahedron in which the Fe atom lies on the inversion center. This is
Fig. 1.ORTH’ drawing the cationic pam of 3, mm.r-lFe- (.NCSMPh,P(oXH,CH,FyO) PhJ, 1’,showing the atOm-label-
ing scheme and 50% probability thermal ellipsoids. Sysnme- try-equivalentatoms (denoted by the letter@ are generated by the center of symmetry
why this molecule has the Z value of 1 instead of 2. In other words, the asymmetric unit of a unit cell contains only one hdf of the molecule. The four oxygen atoms in phosphine oxide ligands occupy the equatorial sites, and the two mans NCS ligands occupy the axial sites. The linear anion (1.J is not bonded to the Fe metal and acts as a counterion, in which the central iodine (12) lies on the crystallographic inversion center. The equatcrkd plane, defied by the Fe and four phosphine oxide oxygen atoms, is essentially planar because it is generated by the crys- tallographic inversion operation.
The Fel -01 and Fe 1-02 bond distances are 1.999(3) i! and 2.005(3)
A,
respectively. The 01-P2 and 02-P1 bond distances are essentially the same (1.493(3) ~). The Fel -N 1 bond distance of 2.027(4) ~ indicates a Fe-N sin- gle bond, because a metal-nitrogen single bond is expect- ed to lie within 1.95-2.15 ik.’” The N 1-C27 bond dis- tance of 1.151(6) ~ indicates an X-C triple bond, and the C27-S 1 bond distance of 1.61 1(5) ~. is significantly shorter than a C-S single bond (1.81 ~) In stnrcturally characterized transition-metal-i sothicwyanato (M-NCS) complexes, the N-C bond distance lies within 1.129-1.164) ~ and the C-S bond distance within 1.632-1.650 k’? The Fel-Nl-C27 and N1-C27-SI bond angles are 157.6(4Y and 178.4(4)0. respectively. Fe(Il)-NCS com- plexes exhibit the Fe-I$CS bond angles in ti wide range of 120-180”, with a preference to the range 150- IW.ifi The bonding parameters of the Fe-NCS group in com- pound 3 indicate a bent Fe-NCS group and suggest the resonance form II to be a major contribution. in which the nirmgen atom is spz-hybridized. In the crystal stnrc- ture of KSCh’. the following bonding parameters were observed (1) The S-C-N moiety is linear with a bond angle of 178( 1~. (2) The S-C bond distance is 1.69(1) ~, considerably shorter than the. C-S single bond distance of
1.81 A. (3) the C-N bond distance is 1.51(1) A taC=N
,lownd cfthe Korean Chemicul .$’oceiet?
triple bond).’>
@
.*C3 fi=c=g:
LnFe—N=C—~O: — ~Fe’
I II
in summary, we have prepared rratrs-[FeH( NCS(Me)- Sldppej~]I (2) by rhe electrophilic attack ot’ icdomethane at the NCS sulfur atom in [runs- [FeH(NCS)(dppe)~l (1).
Compound 2 underwent oxidation to rr-arzs-[Fe(NCS)~- tPhlNOm*CH}(0)W~k]r~] (3) In this OXidabOn Eac-
tion. the Fe metal formally oxidized from +2 to +3, the counterion I from – 1 to – l/3 (in the form of 1,), and the dppe ligands to the corresponding phosphine oxides (Ph*P(0)CHzCHzP(O)PPh!). The molecuku structure of 3 shows a bent Fe-NCS group.
“Ilreaurhors wish to acknowledge the financial support of the Korea Research Foundation made
Year 1997.
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