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Organoimido complexes of tungsten(IV) containing π-acceptor ligands
Polyhedron Vol. 9, No. 4, pp. 603-610, Printed in Great Britain
1990 0
0277-5387/90 s3.00+ .%I 1990 Pergamon Press plc
ORGANOIMIDO COMPLEXES OF TUNGSTEN(W) CONTAINING x-ACCEPTOR LIGANDS ALASTAIR
and DAVID C. WARE
J. NIELSON*
Department of Chemistry, University of Auckland, Private Bag, Auckland, New Zealand (Received
19 July 1989; accepted 18 September
1989)
Abstract-Reaction of PhC=CPh with [WCl,(NR)(PMe,)3] gives the cis-dichloro-transphosphine complexes [WCl,(NR)(PhC=CPh)(PMe,),l [R = Ph (l), R = CHMe* (3)] in which the x-acceptor acetylene ligand lies cis to the imido function. For 1 v(CbC) is at 1760 cm- ’ and for 3, 1740 err- ‘. Me3SiC&SiMe3 and PhC%CPh do not replace phosphine ligands from ~Cl,(NPh)(PMe,),] or [WCl,(NPh)(PMePh,),]. Reaction of PhC&Ph with [WCl,(NPh)(PMe,Ph),] gives [wCl,(NPh)(PhC=CPh)(PMe,Ph),] (2). Alkyl substituted acetylenes do not react cleanly with [WC12(NPh)(PMe3)3] but HC=CH gives [WCl,(NPh)(HC=CH)(PMe,),] (4). Reaction of PhC%CH with pCl,(NR)(PMe,),] gives [WCl,(NR)(PhC&H)(PMe,),l [R = Ph (5), R = CHMe, (611.The phenylacetylene ligand gives rise to asymmetry in 5 and 6 leading to AB system 3’P(‘H} NMR spectra. Different values of ‘J(PW) for the two phosphine ligands in both complexes indicate small differences in W-P bonding. The acetylenic protons and carbons in the ‘H and “C{ ‘H} NMR spectra of the phenylacetylene complexes couple differently to the two phosphines. For 5 3J(HP) cis and tram = 5.90 and 17.26 Hz, 2J(C[H]P) cis and trans = 5.29 and 21.99 Hz and ‘J(C[ph]P) cis and tram = 4.88 and 15.63 Hz. The 13C(‘H) NMR acetylenic carbon resonance positions in complexes 1, 3, 5 and 6 suggest that an isopropylimido ligand is a better n-donor than a phenylimido ligand, allowing more metal-acetylene n-back donation. Reduction of [WCl,(NPh)(PMe,),] with Na/Hg amalgam under CO gives [WCl,(NPh)(GO)(PMe,),] (7) for which v(w) at 1925 cm-’ indicates considerable nbackbonding.
(S2CNMe2)2].7 Several organoimido complexes (MGNR)~ are also known including [W(NR)(L) (S,CNR,)d (L = Me02CC=CC02Me,9 Cd’“),
High valence state complexes which contain both a strong n-donor and a n-acceptor ligand constitute an emerging area of study in early transition metal chemistry. These complexes presently form a basis for studies involving the interaction of multiple bonded organic compounds with high valent metal species in various catalytic processes. ’ Although strong n-donation is normally associated with high valent complexes and n-acceptor ligands with metals in low valency states, there are nevertheless examples known which contain both ligand types. These complexes which mostly contain the terminal 0x0 ligand and have the d2 electron configuration include [Mo(0)(alkyne)(S2CNR2)&2*3 Iw(O)Cl,(L)(PMePh,),] (L = CHdH,, CHCHMe, CHdH-CH=CH2, C=O, Me3CNC),4
[W(O)Cp(C,H,)(PhC=cPh)l,’
IReC13WJW(~1(PPh3)1, ’ ’ [TaC10WWb= CHR)(PMe,)J (R = Me, Ph)‘* and w,Cl,@.= N-N=)(PhG=CPh),(MeOCH,CH,OMe)~. I3 As part of our continuing studies of organoimido chemistry I4we have prepared complexes containing acetylene or carbon monoxide ligands in conjunction with an organoimido function. In particular, the scope of the reaction of [WCl,(NR)(P),] complexes (R = phenyl, alkyl; P = phosphine) with various acetylene ligands and the NMR spectra of the resulting complexes has been studied. A preliminary report of this work has appeared. ’ 5
lWO)CpW=
RESULTS
CH)R] (R = Me, COMe),6 and w(S)(PhC&CPh) *Author to whom correspondence should be addressed.
AND DISCUSSION
When [WC12(NPh)(PMe3)3]16 was refluxed in benzene with dimethyl acetylenedicarboxylate, a
603
A. J. NIELSON
604
brown intractable material formed for which spectral data indicated d~omposition of the acetylene component. However, with diphenylacetylene, one phosphine ligand was replaced giving rise to ~Cl,(NPh)(PhC%CPh)(PMe,),] (1) which, in contrast to mCl,(NPh)(PMe,)3], is air stable. The IR spectrum showed v(Cz&) for the diphenylacetylene ligand as a weak absorption at 1760 cm-’ and v,,,(W-N-C) for the phenylimido ligand at 1350 cm- ’ ” (Table 1). W-Cl stretches at 268 and 245 cm-’ indicated a cis orientation of the two chloro ligands. Is The presence of virtually coupled triplets for the PMe3 ligands in both the ‘H and 13C(*H) NMR spectra” and a singlet with associated tungsten- 183 sidebands in the 3fP( ‘H) NMR spectrum, indicated equivalent tram phosphines (Table 2). Based on this cis-dichlorotrans-phosphine geometry the diphenylacetylene ligand in the complex lies cis to the imido function [Structure (a)].
and D. C. WARE
Symmetry inherent in complex 1 and the bonding modes of the imido and acetylene ligands are apparent from the 13C(‘H) NMR spectrum. The acetylenic carbons appear as a 3‘P-coupled triplet with associated ls3W satellites (‘J(CW) = 28.52 Hz) and are shifted 66 ppm downfield compared with the free ligand. While the ipso-carbon of the aromatic ring is somewhat broadened by poorly resolved coupling to 31P, the or&o-carbons and ipso-carbon of the phenylimido ligand aromatic ring appear as well-defined triplets (4J(CP),,llr,, = 1.89 Hz and 3J(CP),SG = 2.36 Hz). Only the ipso-carbon shows coupling to ‘83W (‘I = 36.29 Hz). The position of the pheny~mido ligand @o-carbon (154.76 ppm) indicates the imido ligand acts as a fourelectron donor to the central tungsten atom. **Thus for the complex to attain an 18-electron configuration the acetylene ligand must represent a two-electron donor. This formalism is evident from the position of the acetylenic carbon resonance (155.77 ppm) which is similar to that shown by two-electron donor diphenylacetylene complexes of molybdenum and tungsten.*’ An X-ray crystal structure dete~nation of ~Ci~~NPh)(Ph~Ph)(PMe3)~ (1)15has confirmed the cis-dichloro-tract-phosphine geometry about the tungsten centre as well as the cis orientation of the phenylimido and diphenylacetylene ligands. The W-N-Ci,id” bond angle of
Table I. Physical data Melting point Complex
v-3
fWCl,(NPh)(Ph~Ph) (PMe3)d (1) wCl,(NPh)(PhC=CPh) (PMe,PhU (2) IWCl,(NCHMe,) (PhCkCPh)(PMe,)d lWCl,(NPh)tH=H) (PMed21(4) fWCl,(NPh)(Ph=H) (PMe,)J (5) ~Cl~(NCHMe~) (Ph~H)(PMe~)~ [WCl,(NPh)(C-=O) (PMe&l(7)
168 154-156 160d (3) 113-115d 147 123-125 (s>” 159
Analytical datab H N 46.6 (46.2) 54.1 (54.0) 42.7 (43.1) 32.4 (32.7) 40.4 (40.0) 37.3 (37.3) 30.2 (29.7)
5.3 (4.9) 4.9 (4.7)
IR data (cm-‘Y v(C=C)
vs,(W-N-k)
‘v(W-4)(cis)
(Z)
1760
1350
268,245
(Z)
1760
1345
260,235
(Z)
1740
1275
270,245
(Z)
1632
1348
275,240
(Z)
1731
1354
271,230
,::a,
1730
1300
265,220
(Z)
P
1345
300,260
(Z) (Z) (Z) ::b (Z)
‘d = decomposition point. bCalculated figures in parentheses. ’ Spectra obtained in Nujol mulls between caesium iodide plates. dContains 1/6&H, solvent molecules. Supported by ‘H NMR spectrum. ev(C%O) 1925 cm-‘.
606
A. J. NIELSON
and D. C. WARE
E
(7)
(6)
214.5 228.5
228.0
- 13.49 - 17.87
-20.74
.209.6 222.7
14.29 and 14.30 [2d (‘J(CP) 31.82 and 29.06 Hz), truns-PMe,] ; 125.32 [t (“J(CP) 1.87 Hz), ortho-Cs, imido]; 126.83 [puru-C, a&]; 126.94 [ortho-Cs, acet] ; 127.32 [par&, imido]; 128.42 [ortho-Cs, a&]; 128.75 [ortho-Cs, imido] ; 140.22 [dd (*J(CP)cis 5.29 Hz, *J(CP)trunr 21.99 Hz, ‘J(CW) 23.11 Hz), &HI; 144.58 [t (3J(CP) 3.35 Hz), @so-C, acet] ; 152.80 [dd ( 2J(CP)ci.r 4.88 Hz, 2J(CP)truns 15.63, ‘J(CW) 31.26 Hz), PhC] ; 154.72 [t ( 3J(CP) 2.32 Hz, ‘J(W) 36.47 Hz), ipso-C, imido] 14.24 and 14.32 [2d (‘J(CP) 31.16 and 29.38), trans-PMe,]; 21.95 and 22.22 [2s, 2Me]; 63.05 [s, ‘J(CW) 30.86 Hz), CH]; 125.43 [puru-c] ; 125.69 [ortho-Cs]; 127.18 [metu-Cs], 135.33 [dd (‘J(CP)cis 5.45 Hz, ‘J(CP)rrans 22.10 Hz, ‘J&W) 23.12 Hz), &HI; 143.55 [t (‘J&P) 3.07 Hz), ipso-C] ; 148.54 [dd (2J(CP)ci.s 5.04 Hz; *J(CP)trans 15.71 Hz, ‘J(CW) 31.27 Hz), PhC+ 14.35 [t (‘J(CP) 14.79 Hz), trans-PMe,]; 124.15 [t (4J(CP) 1.53 Hz), ortho-Cs]; 125.57 [puruC]; 127.92 [metu-Cs]; 153.69 [t (3J(CP) 1.77 Hz), ipso-C] ; 237.19 [t (2J(CP) 4.78 Hz), CO]
1.47 and 1.83 [2d (*J(HP) 9.77 and 9.87 Hz), 18H, 2PMeJ; 7.03 [d (3J(HH) 7.51 Hz), o&oHs, imido] ; 7.13 [t (3J(HH) 7.37 Hz), paw-H, imido] ; 7.19-7.25 [m, 3H, metu-, puru-Hs, acet] ; 7.28 [dd (3J(HH) 6.81 Hz, 4J(HH) 1.39 Hz), ortho-Hs, acet] ; 7.38 [t (3J(HH) 7.60 Hz), meta-Hs, imido]; 9.91 [dd, (3J(HP)cis 5.90 Hz, 3J(HP) tram 17.26 Hz), lH, acet]
1.04 and 1.06 [2d (‘J(HH) 6.48 Hz), 6H, 2Me] ; 1.50 and 1.87 [2d (2J(HP) 9.67 and 9.77 Hz), 18H, 2PMe,]; 3.82 [sept (3J(HH) 6.04 Hz), lH, CH]; 7.13-7.25 [m, 3H, metu-, puru-Hs]; 7.29-7.38 [m, 2H, ortho-Hs]; 9.55 [dd (3J(HP)cis 5.97 Hz, 3J(HP)trans 16.60 Hz), lH, CH]
1:61 [t (2J(HP) 4.16 Hz), 18H, 2PMe,]; 6.977.03 [dd (3J(HH) 8.01 Hz, 4J(HH) 1.39 Hz), 2H, ortho-Hs] ; 7.1 l-7.20 [m, 3H, metu-, puru-Hs]
tiSpectra obtained in CDCl,. *d = doublet, dd = doublet of doublets, m = multiplet, prt = poorly resolved triplet, s = singlet, sept = septet, t = triplet. ‘Aromatic ring resonances assigned by spectral comparisons of complexes; metu-Cs based on 6128.5, puru-Cs from relative peak height, ortho-Cs as triplets for phenylimido ligands, otherwise tentative. “‘.J(PP) = 164.31 Hz. ’ ‘J(PP) = 156.45 Hz.
WClfiPh)(C=W’Me&I
[WCl,(NCHMe&PhWH)(PMe,)J
- 13.30 - 17.72
s 3
3
8 3 z ! % 2
4_’
Q B E. 3
608
A. J. NIELSON
the phosphines are trans,26 with the doublets arising from non-equivalent PMe, ligands.* The ‘H and ‘3C{‘H} NMR spectra of the PMe, ligands show virtual coupling and the 3’P{‘H} NMR spectrum represents an AB system which has been simulated.28 The two phosphines show different 3’P-‘83W couplings (‘J(PW) = 209.6 and 222.7 Hz) suggesting small differences in the W-P bonding modes. 27*29 Asymmetry present in the complex has a marked effect on the appearance of the acetylenic carbons and proton in the NMR spectra. The CH proton in the ‘H NMR spectrum is a doublet of doublets showing different coupling to the phosphines which lie cis and tram to it (3J(HP),is = 5.90 Hz, 3J(HP),,,, = 17.26 Hz). Variable-temperature studies to 80°C (353 K) show no change in the spectrum ruling out fluxional processes such as rotation or dissociation. Simulation shows that the doublet of doublets is the X part of an AMX system while the coupling pattern is confirmed in the proton coupled 3‘P NMR spectrum. Each line of the phosphine doublet of doublet AB system splits further with the lower field portion (6 = -13.30 ppm) showing 3J(HP) of 17.26 Hz while for the higher field portion, 3J(HP) is 5.90 Hz. Simulation shows the expected 20-line spectrum consisting of 10 doublet sets. The acetylenic CH carbon in the 13C(‘H} NMR spectrum appears as a doublet of doublets for which ‘J(CP),, is 5.29 Hz and *J(CP)‘,,,, is 21.99 Hz, and the phenyl substituted acetylenic carbon is also a doublet of doublets with *J(CP),, 4.88 Hz and 2J(CP)IIMs 15.63 Hz. Simulation of these carbonphosphorus coupled spectra show they are AMX systems. The two acetylenic carbons exhibit different C-W coupling constants (‘J(C[H]W) = 23.11 Hz, ‘J(C[Ph]W) = 31.26 Hz) which is consistent with the two different carbons being non-equivalent. Of the remaining 3’P-coupled carbon resonances in the spectrum, the phenylimido ortho- and ipso-carbons and the phenylacetylene ipso-carbons all appear as triplets. ~C12(NCHMe,)(PhC=CH)(PMe3)2] (6) was prepared for spectral comparison with phenylimido complex 5. The isopropylimido ligand methyl groups of this cis-dichloro-trans-phosphine complex appear in the ‘H NMR spectrum as two doublets which arise due to asymmetry present in the molecule. Similar to the phenylimido complex 5, * The 2J(PP) coupling constant value is similar to that found for [wCl,(NPh)(Me,C==CH,)(PMe,)d which shows an AB pattern in the 3’P{ ‘H} NMR spectrum for trans-orientated PMe, ligands, confirmed by an X-ray crystal structure.27
and D. C. WARE the acetylenic proton for 6 is a doublet of doublets in the ‘H NMR spectrum (3J(HP),, = 5.97 Hz, 3J(HP),,m, = 16.60 Hz), the acetylenic carbons in the 13C(‘H) NMR spectrum are doublet of doublets and the phenylacetylene ipso-carbon is a triplet. However, the positions of the acetylenic carbon resonances in 5 and 6 are different (i.e. for 5 and 6, CH at 140.22 and 135.33 ppm, respectively, CPh at 152.80 and 148.54 ppm, respectively) which suggests a small increase in n-backbonding in 6. 24This feature was also found for complexes 2 and 1 and indicates that the isopropylimido ligand is a slightly better n-donor than the phenylimido ligand. The 3‘P{ ‘H} NMR spectrum AB systems are similar in both complexes, but ‘J(PP) for 6 is smaller (156.45 Hz cf. 164.3 1 Hz for 5). The ‘J(PW) values of 214.5 and 228.5 Hz for 6 again suggest small differences in the W-P bonding modes.27,29 Carbon monoxide also replaces one phosphine ligand from [WC12(NPh)(PMe3)3] under reflux in benzene, but a cleaner reaction occurs when [wCl,(NPh)(PMe,),] is reduced in the presence of C+O with one equivalent of Na/Hg amalgam. This reductive process does not give the previously described acetylene complexes cleanly but does give good yields of olefin-imido complexes.27 [WC12(NPh)(C=O)(PMe3)2] (7) is a purple, airstable solid for which IR and NMR spectral data show the same cis-dichloro-trans-phosphine geometry exhibited by the acetylene complexes which places the C=O ligand cis to the imido function. v(C&O) lies at 1925 cm-’ in the IR spectrum indicating significant backbonding to CZO.~’ In comparison, v(C=O) is found at 2006 cm-’ for lWC12(0)(C=O)(PMePh2)2],4 2040 cm- ’ for [ReCl,(NPh)(C=O)(PPh,)],” and 1912 cm- ’ for [W(NPh)(S2CNEt2)2(C=O)].‘o In the 13C{‘H} NMR spectrum the phenylimido ligand ipso- and ortho-carbons show the normal triplet as does the CGO carbon (*J(CP) = 4.78 Hz). EXPERIMENTAL
lYCMNW(PMe3)31, lY~~2WWMeJ’h)~1 and wC12(NCHMe2)(PMe3)3] were prepared by Na/Hg amalgam reduction of [WCl,(NPh)], or [WC14(NCHMe2)12 in the presence of the appropriate phosphine, and [WC13(NPh)(PMe3)2] by reaction of [WC14(NPh)12 with PMe3 in THF.16 Commercial acetylene and carbon monoxide were used as supplied. Petroleum ether (b.p. 4060°C) and benzene were distilled from sodium wire. All distillations and bench-top manipulations were carried out under N, treated to remove oxygen and water 3’ IR spectra were recorded on a PerkinElmer 597 spectrometer and ‘H NMR (400 MHz),
Organoimido complexes of tungsten(IV)
13C(‘H) NMR (100.6 MHz) and 3’P{1H} NMR (162 MHz) spectra on a Bruker AM400 spectrometer. Analytical data were obtained by Professor A. D. Campbel and his associates, University of Otago, New Zealand. Melting points were determined in sealed tubes under N2 on an electrothermal melting point apparatus and are uncorrected. Dichloro (diphenylacetylene) phenylimidobis (trimethylphosphine)tungsten(IV) (1)
Diphenylacetylene (0.5 g, 2.8 mmol) in benzene (30 cm3) was added to dichloro(phenylimido) tris(trimethylphosphine)tungsten(IV) (1 .O g, 1.74 mmol) in benzene (80 cm’) and the mixture was refluxed for 20 h. The solution was filtered and the solvent removed to give a yellow gum which solidified on washing with petroleum ether (50 cm3). Crude yield, 1.0 g (85%). An analytically pure sample was obtained by extracting the crude product with petroleum ether (5 x 100 cm3), combining the extracts, and reducing the volume to give the complex as yellow crystals (0.35 g). IR (Nujol) 176Obm, 1578m, 157Om, 1555w, 1460s 14OOm,1330s 1292m, 1271s 114Ow, 1085w, 1055m, lOlOm, 995w, 975m, 935vs, 904m, 878w, 845m, 836m, 768s 757s 750s 740m, 727s 690s 678s, 672m, 62Ow, 611w, 583w, 564m, 554m, 538w, 527w, 48Ow, 458w, 395w, 373w, 345w, 258m, 255s 230s and 215m cm-‘.
609
(80 cm’) for 18 h. The solution was filtered, the volume reduced to cu 15 cm3 and petroleum ether (100 cm3) added. On standing, colourless crystals of the complex were formed. Yield, 0.36 g (76%). IR (Nujol) 1740bw, 1595w, 1480m, 142Om, 1378m, 1300m, 1275s, 1155w, lllOw, 1068w, 1024w, 95Os, 865m, 785s 778m, 755s 722s 705s 68Ow, 632w, 584m, 565w, 558w, 510m, 475w, 458w, 41Ow, 270s and 245s cm-‘. Acetylenedichlorophenylimidobis (trimethylphosphine) tungsten(W) (4)
Dichloro (phenylimido) tris (trimethylphosphine) tungsten(IV) (0.7 g, 1.2 mmol) was refluxed in benzene (80 cm3) for 16 h under an acetylene atmosphere (balloon). The solution was filtered while hot, and the volume reduced to ca 40 cm3 keeping the solution hot. On standing, yellow microcrystals of the product separated (0.4 g) which were filtered off and washed with petroleum ether (50 cm’). Addition of petroleum ether (50 cm’) to the filtrate gave a further crop of yellow microcrystals (0.2 g). Total yield, 94%. IR (Nujol) 1632w, 1582w, 1482s, 1462s 1423m, 1348s, 1305w, 1294m, 1288m, 1282m, 1173w, 1256w, 1074w, 1028w, 1008w, 996m, 988m, 955~s 868m, 860m, 777m, 768s 75Om, 745s 725w, 700s 683w, 675w, 63Ow, 625w, 56Ow, 538w, 496w, 398w, 355w, 285m, 275s and 240s cm- ‘.
Dichlorobis (dimethy@eny&hosphine) diphenylacetylene(phenylimido)tungsten(Zv (2)
Dichloro (phenylacetylene) phenylimidobis (trimethylphosphine)tungsten(IV) (5)
Diphenylacetylene (0.25 g, 1.4 mmol) and dichlorotris (dimethylphenylphosphine) phenylimidotungsten (IV) (0.9 g, 1.2 mmol) were refluxed in benzene (30 cm3) for 16 h. The solution was filtered, the solvent removed and the residue washed with petroleum ether (100 cm’). Crude yield, 0.8 g (84%). Concentration of the petroleum ether extracts (5 x 100 cm’) gave the complex as yellow crystals (0.2 g). IR (Nujol) 176Ow, 159Ow, 1564w, 1345m, 1294w, 1272w, 1255w, 1134w, 1lOOw, 106Ow, 1018w, 988w, 944m, 922s 910s 904s, 864w, 845w, 83Ow, 795w, 775m, 760s 742s 718m, 690m, 680s 670m, 684s 585w, 57Om, 560m, 544w, 525w, 484m, 455w, 415w, 378w, 335w, 260m and 235m cm-‘.
Phenylacetylene (0.16 g, 1.6 mmol) in benzene (30 cm’) was added to dichloro@henylimido) tris(trimethylphosphine)tungsten(IV) (0.8 g, 1.4 mmol) in benzene (80 cm3) and the mixture was refluxed for 18 h. The solution was filtered and the solvent removed to give a gum which solidified on standing under petroleum ether (100 cm3). Crude yield, 0.74 g (88%). Combination of petroleum ether extracts (3 x 100 cm3) and reduction of the volume gave the complex as yellow crystals (0.3 g). IR(Nujo1) 1731bw, 1595w, 158Ow, 1462m, 1415s 1354s, 1308w, 1285m, 1162~. 1071m, 1028m, 990m, 950~s 857m, 784s 770s 745s 73Ow, 710s 7OOs, 682w, 635w, 628w, 565w, 552w, 538w, 528w, 515w, 398w, 353w, 271s 248m, 230s and 208m cm-‘.
Dichloro (diphenylacetylene) isopropylimidobis (trimethylphosphine)tungsten(IV) (3)
Diphenylacetylene (0.2 g, 1.1 mmol) and dichloro (isopropylimido) tris (trimethylphosphine) tungsten (IV) (0.4 g, 0.74 mmol) were refluxed in benzene
Dichloro(bopropylim~o)phenylacetyle~b~(trimethylphosphine)tungsten(IV) (6)
Dichloro(isopropylimido)tris(trimethylphosphine) tungsten(IV) (0.9 g, 1.7 mmol) and phenylacetyl-
610
A. J. NIELSON
ene (0.2 g, 2.0 mmol) in benzene (100 cm3) were re-
fluxed for 16 h. The solution was filtered, the volume reduced to ca 25 cm3 and petroleum ether (100 cm’) added, giving the complex as a yellow noncrystalline solid which was filtered off, washed with petroleum ether (30 cm’) and dried in vacua. Yield, 0.53 g (55%). IR (Nujol) 173Om, 159Ow, 1475s, 1412s, 1350m, 13OOm, 1268s, 1165w, 1145w, lllOw, 1068w, 102Ow, 95Ovs, 858m, 8OOw,76Os, 75Os, 735s, 704s, 675m, 630m, 618w, 565w, 52Ow, 345w, 265s and 220m cm-‘. Carbonyldichloro (phenylimido) bis (trimethylphosphine)tungsten(IV) (7)
Trichloro (phenylimido) bis(trimethylphosphine) tungsten(V) (1 .O g, 1.9 mmol) in benzene (100 cm3) was reduced with Na/Hg amalgam (50 mg Na, 2.2 mmol; 40 g Hg) under carbon monoxide (20 p.s.i.) for 5 h. The solution was filtered and the solvent removed to give a purplebrown crystalline solid which was extracted with warm petroleum ether (5 x 200 cm3). The combined extracts were filtered and the solvent reduced to ca 5 cm3 giving the complex as a purple crystalline solid. Yield, 0.7 g (70%). IR (Nujol) 1925s, 1464s 1418s, 1345s, 1305m, 1284s 116Ow, 107Ow, 1025w, 945s 860m, 855m, 775s, 742s, 695s, 670m, 570m, 558m, 46Ow, 38Ow, 34Ow, 305s and 260s cm-‘. REFERENCES 1. W. A. Nugent and J. M. Mayer, Metal-Ligand Multiple Bona!s. Wiley Interscience, New York (1988). 2. E. A. Maatta and R. A. D. Wentworth, Znorg. Chem. 1979, 18, 524. 3. W. E. Newton, J. W. McDonald, J. L. Corbin, L. Ricard and R. Weiss, Znorg. Chem. 1980, 19, 1997. 4. F.-M. Su, C. Cooper, S. J. Geib, A. L. Rheingold and J. M. Mayer, J. Am. Chem. Sot. 1986,108,3545. 5. N. G. Bokiy, Yu. V. Gatilov, Yu. T. Struchkov and N. A. Ustynyuk, J. Organomet. Chem. 1973,54,213. 6. H. G. Alt and H. I. Hayen, J. Organomet. Chem. 1986,316, 105. 7. J. R. Morrow, T. L. Tonker and J. L. Templeton, Organometallics 1985,4, 745. 8. W. A. Nugent and B. L. Haymore, Coord. Chem. Rev. 1980, 31, 123.
and D. C. WARE 9. D. D. Devore, E. A. Maatta and F. Takusagawa, Znorg. Chim. Acta 1986, 112, 87. 10. G. L. Hillhouse and B. L. Haymore, J. Organomet. Chem. 1978,162, C23. 11. G. La Monica and S. Cenini, Znorg. Chim. Acta 1978, 29, 183; J. Chem. Sot., Dalton Trans. 1980, 1145. 12. S. M. Rocklage and R. R. Schrock, J. Am. Chem. Sot. 1982,104,3077. 13. M. R. Churchill, Y.-J. Li, K. H. Theopold and R. R. Schrock, Znorg. Chem. 1984,23,4472. 14. A. J. Nielson, Chem. N.Z. 1988,52, 131. 15. G. R. Clark, A. J. Nielson, C. E. F. Rickard and D. C. Ware, J. Chem. Sot., Chem. Commun. 1989, 343. 16. D. C. Bradley, M. B. Hursthouse, K. M. A. Malik, A. J. Nielson and R. L. Short, J. Chem. Sot., Dalton Trans. 1983,265l ; A. J. Nielson, Znorg. Synth. 1986, 24,193. 17. W. P. Griffith, A. J. Nielson and M. J. Taylor, J. Chem. Sot., Dalton Trans. 1988,647. 18. K. Nakamoto, Infrared and Raman Spectra qf Znorganic and Coordination Compounds, 4th edn, p. 327. John Wiley, New York (1986). 19. D. A. Redfield, J. H. Nelson and L. W. Cory, Znorg. Nucl. Chem. Lett. 1974, 10, 727. 20. B. R. Ashcroft, A. J. Nielson, D. C. Bradley, R. J. Errington, M. B. Hursthouse and R. L. Short, J. Chem. Sot., Dalton Trans. 1987,2059. 21. J. L. Templeton and B. C. Ward, J. Am. Chem. Sot. 1980, 102,3288. 22. E. C. Walborsky, D. E. Wigley, E. Roland, J. C. Dewar and R. R. Schrock, Znorg. Chem. 1987, 26, 1615. 23. W. A. Nugent and J. M. Mayer, Metal-Ligand Multiple Bonds, p. 33. Wiley Interscience, New York (1988). 24. C. A. Tolman, A. D. English and L. E. Manzer, Znorg. Chem. 1975, 14, 2353. 25. A. J. Nielson, J. M. Waters and D. C. Bradley, Polyhedron 1985,4,285. 26. J. G. Verkade, Coord. Chem. Rev. 1972/73,9, 1. 27. G. R. Clark, A. J. Nielson, C. E. F. Rickard and D. C. Ware, J. Chem. Sot., Dalton Trans., in press. 28. A. J. Nielson and D. C. Ware, unpublished work. 29. F. A. Cotton and G. N. Mott, J. Am. Chem. Sot. 1982, 104, 5978 ; P. S. Pregosin and R. W. Kunz, NMR, Basic Principles and Progress (Edited by P. Diehl, E. Fluck and R. Kosfield), Vol. 16, p. 25. Springer, Berlin (1979). 30. K. Nakamoto, Infrared and Raman Spectra of Znorganic and Coordination Compounds, 4th edn, p. 291. John Wiley, New York (1986). 31. A. J. Nielson, Chem. N.Z. 1985, 49, 11.
1990 0
0277-5387/90 s3.00+ .%I 1990 Pergamon Press plc
ORGANOIMIDO COMPLEXES OF TUNGSTEN(W) CONTAINING x-ACCEPTOR LIGANDS ALASTAIR
and DAVID C. WARE
J. NIELSON*
Department of Chemistry, University of Auckland, Private Bag, Auckland, New Zealand (Received
19 July 1989; accepted 18 September
1989)
Abstract-Reaction of PhC=CPh with [WCl,(NR)(PMe,)3] gives the cis-dichloro-transphosphine complexes [WCl,(NR)(PhC=CPh)(PMe,),l [R = Ph (l), R = CHMe* (3)] in which the x-acceptor acetylene ligand lies cis to the imido function. For 1 v(CbC) is at 1760 cm- ’ and for 3, 1740 err- ‘. Me3SiC&SiMe3 and PhC%CPh do not replace phosphine ligands from ~Cl,(NPh)(PMe,),] or [WCl,(NPh)(PMePh,),]. Reaction of PhC&Ph with [WCl,(NPh)(PMe,Ph),] gives [wCl,(NPh)(PhC=CPh)(PMe,Ph),] (2). Alkyl substituted acetylenes do not react cleanly with [WC12(NPh)(PMe3)3] but HC=CH gives [WCl,(NPh)(HC=CH)(PMe,),] (4). Reaction of PhC%CH with pCl,(NR)(PMe,),] gives [WCl,(NR)(PhC&H)(PMe,),l [R = Ph (5), R = CHMe, (611.The phenylacetylene ligand gives rise to asymmetry in 5 and 6 leading to AB system 3’P(‘H} NMR spectra. Different values of ‘J(PW) for the two phosphine ligands in both complexes indicate small differences in W-P bonding. The acetylenic protons and carbons in the ‘H and “C{ ‘H} NMR spectra of the phenylacetylene complexes couple differently to the two phosphines. For 5 3J(HP) cis and tram = 5.90 and 17.26 Hz, 2J(C[H]P) cis and trans = 5.29 and 21.99 Hz and ‘J(C[ph]P) cis and tram = 4.88 and 15.63 Hz. The 13C(‘H) NMR acetylenic carbon resonance positions in complexes 1, 3, 5 and 6 suggest that an isopropylimido ligand is a better n-donor than a phenylimido ligand, allowing more metal-acetylene n-back donation. Reduction of [WCl,(NPh)(PMe,),] with Na/Hg amalgam under CO gives [WCl,(NPh)(GO)(PMe,),] (7) for which v(w) at 1925 cm-’ indicates considerable nbackbonding.
(S2CNMe2)2].7 Several organoimido complexes (MGNR)~ are also known including [W(NR)(L) (S,CNR,)d (L = Me02CC=CC02Me,9 Cd’“),
High valence state complexes which contain both a strong n-donor and a n-acceptor ligand constitute an emerging area of study in early transition metal chemistry. These complexes presently form a basis for studies involving the interaction of multiple bonded organic compounds with high valent metal species in various catalytic processes. ’ Although strong n-donation is normally associated with high valent complexes and n-acceptor ligands with metals in low valency states, there are nevertheless examples known which contain both ligand types. These complexes which mostly contain the terminal 0x0 ligand and have the d2 electron configuration include [Mo(0)(alkyne)(S2CNR2)&2*3 Iw(O)Cl,(L)(PMePh,),] (L = CHdH,, CHCHMe, CHdH-CH=CH2, C=O, Me3CNC),4
[W(O)Cp(C,H,)(PhC=cPh)l,’
IReC13WJW(~1(PPh3)1, ’ ’ [TaC10WWb= CHR)(PMe,)J (R = Me, Ph)‘* and w,Cl,@.= N-N=)(PhG=CPh),(MeOCH,CH,OMe)~. I3 As part of our continuing studies of organoimido chemistry I4we have prepared complexes containing acetylene or carbon monoxide ligands in conjunction with an organoimido function. In particular, the scope of the reaction of [WCl,(NR)(P),] complexes (R = phenyl, alkyl; P = phosphine) with various acetylene ligands and the NMR spectra of the resulting complexes has been studied. A preliminary report of this work has appeared. ’ 5
lWO)CpW=
RESULTS
CH)R] (R = Me, COMe),6 and w(S)(PhC&CPh) *Author to whom correspondence should be addressed.
AND DISCUSSION
When [WC12(NPh)(PMe3)3]16 was refluxed in benzene with dimethyl acetylenedicarboxylate, a
603
A. J. NIELSON
604
brown intractable material formed for which spectral data indicated d~omposition of the acetylene component. However, with diphenylacetylene, one phosphine ligand was replaced giving rise to ~Cl,(NPh)(PhC%CPh)(PMe,),] (1) which, in contrast to mCl,(NPh)(PMe,)3], is air stable. The IR spectrum showed v(Cz&) for the diphenylacetylene ligand as a weak absorption at 1760 cm-’ and v,,,(W-N-C) for the phenylimido ligand at 1350 cm- ’ ” (Table 1). W-Cl stretches at 268 and 245 cm-’ indicated a cis orientation of the two chloro ligands. Is The presence of virtually coupled triplets for the PMe3 ligands in both the ‘H and 13C(*H) NMR spectra” and a singlet with associated tungsten- 183 sidebands in the 3fP( ‘H) NMR spectrum, indicated equivalent tram phosphines (Table 2). Based on this cis-dichlorotrans-phosphine geometry the diphenylacetylene ligand in the complex lies cis to the imido function [Structure (a)].
and D. C. WARE
Symmetry inherent in complex 1 and the bonding modes of the imido and acetylene ligands are apparent from the 13C(‘H) NMR spectrum. The acetylenic carbons appear as a 3‘P-coupled triplet with associated ls3W satellites (‘J(CW) = 28.52 Hz) and are shifted 66 ppm downfield compared with the free ligand. While the ipso-carbon of the aromatic ring is somewhat broadened by poorly resolved coupling to 31P, the or&o-carbons and ipso-carbon of the phenylimido ligand aromatic ring appear as well-defined triplets (4J(CP),,llr,, = 1.89 Hz and 3J(CP),SG = 2.36 Hz). Only the ipso-carbon shows coupling to ‘83W (‘I = 36.29 Hz). The position of the pheny~mido ligand @o-carbon (154.76 ppm) indicates the imido ligand acts as a fourelectron donor to the central tungsten atom. **Thus for the complex to attain an 18-electron configuration the acetylene ligand must represent a two-electron donor. This formalism is evident from the position of the acetylenic carbon resonance (155.77 ppm) which is similar to that shown by two-electron donor diphenylacetylene complexes of molybdenum and tungsten.*’ An X-ray crystal structure dete~nation of ~Ci~~NPh)(Ph~Ph)(PMe3)~ (1)15has confirmed the cis-dichloro-tract-phosphine geometry about the tungsten centre as well as the cis orientation of the phenylimido and diphenylacetylene ligands. The W-N-Ci,id” bond angle of
Table I. Physical data Melting point Complex
v-3
fWCl,(NPh)(Ph~Ph) (PMe3)d (1) wCl,(NPh)(PhC=CPh) (PMe,PhU (2) IWCl,(NCHMe,) (PhCkCPh)(PMe,)d lWCl,(NPh)tH=H) (PMed21(4) fWCl,(NPh)(Ph=H) (PMe,)J (5) ~Cl~(NCHMe~) (Ph~H)(PMe~)~ [WCl,(NPh)(C-=O) (PMe&l(7)
168 154-156 160d (3) 113-115d 147 123-125 (s>” 159
Analytical datab H N 46.6 (46.2) 54.1 (54.0) 42.7 (43.1) 32.4 (32.7) 40.4 (40.0) 37.3 (37.3) 30.2 (29.7)
5.3 (4.9) 4.9 (4.7)
IR data (cm-‘Y v(C=C)
vs,(W-N-k)
‘v(W-4)(cis)
(Z)
1760
1350
268,245
(Z)
1760
1345
260,235
(Z)
1740
1275
270,245
(Z)
1632
1348
275,240
(Z)
1731
1354
271,230
,::a,
1730
1300
265,220
(Z)
P
1345
300,260
(Z) (Z) (Z) ::b (Z)
‘d = decomposition point. bCalculated figures in parentheses. ’ Spectra obtained in Nujol mulls between caesium iodide plates. dContains 1/6&H, solvent molecules. Supported by ‘H NMR spectrum. ev(C%O) 1925 cm-‘.
606
A. J. NIELSON
and D. C. WARE
E
(7)
(6)
214.5 228.5
228.0
- 13.49 - 17.87
-20.74
.209.6 222.7
14.29 and 14.30 [2d (‘J(CP) 31.82 and 29.06 Hz), truns-PMe,] ; 125.32 [t (“J(CP) 1.87 Hz), ortho-Cs, imido]; 126.83 [puru-C, a&]; 126.94 [ortho-Cs, acet] ; 127.32 [par&, imido]; 128.42 [ortho-Cs, a&]; 128.75 [ortho-Cs, imido] ; 140.22 [dd (*J(CP)cis 5.29 Hz, *J(CP)trunr 21.99 Hz, ‘J(CW) 23.11 Hz), &HI; 144.58 [t (3J(CP) 3.35 Hz), @so-C, acet] ; 152.80 [dd ( 2J(CP)ci.r 4.88 Hz, 2J(CP)truns 15.63, ‘J(CW) 31.26 Hz), PhC] ; 154.72 [t ( 3J(CP) 2.32 Hz, ‘J(W) 36.47 Hz), ipso-C, imido] 14.24 and 14.32 [2d (‘J(CP) 31.16 and 29.38), trans-PMe,]; 21.95 and 22.22 [2s, 2Me]; 63.05 [s, ‘J(CW) 30.86 Hz), CH]; 125.43 [puru-c] ; 125.69 [ortho-Cs]; 127.18 [metu-Cs], 135.33 [dd (‘J(CP)cis 5.45 Hz, ‘J(CP)rrans 22.10 Hz, ‘J&W) 23.12 Hz), &HI; 143.55 [t (‘J&P) 3.07 Hz), ipso-C] ; 148.54 [dd (2J(CP)ci.s 5.04 Hz; *J(CP)trans 15.71 Hz, ‘J(CW) 31.27 Hz), PhC+ 14.35 [t (‘J(CP) 14.79 Hz), trans-PMe,]; 124.15 [t (4J(CP) 1.53 Hz), ortho-Cs]; 125.57 [puruC]; 127.92 [metu-Cs]; 153.69 [t (3J(CP) 1.77 Hz), ipso-C] ; 237.19 [t (2J(CP) 4.78 Hz), CO]
1.47 and 1.83 [2d (*J(HP) 9.77 and 9.87 Hz), 18H, 2PMeJ; 7.03 [d (3J(HH) 7.51 Hz), o&oHs, imido] ; 7.13 [t (3J(HH) 7.37 Hz), paw-H, imido] ; 7.19-7.25 [m, 3H, metu-, puru-Hs, acet] ; 7.28 [dd (3J(HH) 6.81 Hz, 4J(HH) 1.39 Hz), ortho-Hs, acet] ; 7.38 [t (3J(HH) 7.60 Hz), meta-Hs, imido]; 9.91 [dd, (3J(HP)cis 5.90 Hz, 3J(HP) tram 17.26 Hz), lH, acet]
1.04 and 1.06 [2d (‘J(HH) 6.48 Hz), 6H, 2Me] ; 1.50 and 1.87 [2d (2J(HP) 9.67 and 9.77 Hz), 18H, 2PMe,]; 3.82 [sept (3J(HH) 6.04 Hz), lH, CH]; 7.13-7.25 [m, 3H, metu-, puru-Hs]; 7.29-7.38 [m, 2H, ortho-Hs]; 9.55 [dd (3J(HP)cis 5.97 Hz, 3J(HP)trans 16.60 Hz), lH, CH]
1:61 [t (2J(HP) 4.16 Hz), 18H, 2PMe,]; 6.977.03 [dd (3J(HH) 8.01 Hz, 4J(HH) 1.39 Hz), 2H, ortho-Hs] ; 7.1 l-7.20 [m, 3H, metu-, puru-Hs]
tiSpectra obtained in CDCl,. *d = doublet, dd = doublet of doublets, m = multiplet, prt = poorly resolved triplet, s = singlet, sept = septet, t = triplet. ‘Aromatic ring resonances assigned by spectral comparisons of complexes; metu-Cs based on 6128.5, puru-Cs from relative peak height, ortho-Cs as triplets for phenylimido ligands, otherwise tentative. “‘.J(PP) = 164.31 Hz. ’ ‘J(PP) = 156.45 Hz.
WClfiPh)(C=W’Me&I
[WCl,(NCHMe&PhWH)(PMe,)J
- 13.30 - 17.72
s 3
3
8 3 z ! % 2
4_’
Q B E. 3
608
A. J. NIELSON
the phosphines are trans,26 with the doublets arising from non-equivalent PMe, ligands.* The ‘H and ‘3C{‘H} NMR spectra of the PMe, ligands show virtual coupling and the 3’P{‘H} NMR spectrum represents an AB system which has been simulated.28 The two phosphines show different 3’P-‘83W couplings (‘J(PW) = 209.6 and 222.7 Hz) suggesting small differences in the W-P bonding modes. 27*29 Asymmetry present in the complex has a marked effect on the appearance of the acetylenic carbons and proton in the NMR spectra. The CH proton in the ‘H NMR spectrum is a doublet of doublets showing different coupling to the phosphines which lie cis and tram to it (3J(HP),is = 5.90 Hz, 3J(HP),,,, = 17.26 Hz). Variable-temperature studies to 80°C (353 K) show no change in the spectrum ruling out fluxional processes such as rotation or dissociation. Simulation shows that the doublet of doublets is the X part of an AMX system while the coupling pattern is confirmed in the proton coupled 3‘P NMR spectrum. Each line of the phosphine doublet of doublet AB system splits further with the lower field portion (6 = -13.30 ppm) showing 3J(HP) of 17.26 Hz while for the higher field portion, 3J(HP) is 5.90 Hz. Simulation shows the expected 20-line spectrum consisting of 10 doublet sets. The acetylenic CH carbon in the 13C(‘H} NMR spectrum appears as a doublet of doublets for which ‘J(CP),, is 5.29 Hz and *J(CP)‘,,,, is 21.99 Hz, and the phenyl substituted acetylenic carbon is also a doublet of doublets with *J(CP),, 4.88 Hz and 2J(CP)IIMs 15.63 Hz. Simulation of these carbonphosphorus coupled spectra show they are AMX systems. The two acetylenic carbons exhibit different C-W coupling constants (‘J(C[H]W) = 23.11 Hz, ‘J(C[Ph]W) = 31.26 Hz) which is consistent with the two different carbons being non-equivalent. Of the remaining 3’P-coupled carbon resonances in the spectrum, the phenylimido ortho- and ipso-carbons and the phenylacetylene ipso-carbons all appear as triplets. ~C12(NCHMe,)(PhC=CH)(PMe3)2] (6) was prepared for spectral comparison with phenylimido complex 5. The isopropylimido ligand methyl groups of this cis-dichloro-trans-phosphine complex appear in the ‘H NMR spectrum as two doublets which arise due to asymmetry present in the molecule. Similar to the phenylimido complex 5, * The 2J(PP) coupling constant value is similar to that found for [wCl,(NPh)(Me,C==CH,)(PMe,)d which shows an AB pattern in the 3’P{ ‘H} NMR spectrum for trans-orientated PMe, ligands, confirmed by an X-ray crystal structure.27
and D. C. WARE the acetylenic proton for 6 is a doublet of doublets in the ‘H NMR spectrum (3J(HP),, = 5.97 Hz, 3J(HP),,m, = 16.60 Hz), the acetylenic carbons in the 13C(‘H) NMR spectrum are doublet of doublets and the phenylacetylene ipso-carbon is a triplet. However, the positions of the acetylenic carbon resonances in 5 and 6 are different (i.e. for 5 and 6, CH at 140.22 and 135.33 ppm, respectively, CPh at 152.80 and 148.54 ppm, respectively) which suggests a small increase in n-backbonding in 6. 24This feature was also found for complexes 2 and 1 and indicates that the isopropylimido ligand is a slightly better n-donor than the phenylimido ligand. The 3‘P{ ‘H} NMR spectrum AB systems are similar in both complexes, but ‘J(PP) for 6 is smaller (156.45 Hz cf. 164.3 1 Hz for 5). The ‘J(PW) values of 214.5 and 228.5 Hz for 6 again suggest small differences in the W-P bonding modes.27,29 Carbon monoxide also replaces one phosphine ligand from [WC12(NPh)(PMe3)3] under reflux in benzene, but a cleaner reaction occurs when [wCl,(NPh)(PMe,),] is reduced in the presence of C+O with one equivalent of Na/Hg amalgam. This reductive process does not give the previously described acetylene complexes cleanly but does give good yields of olefin-imido complexes.27 [WC12(NPh)(C=O)(PMe3)2] (7) is a purple, airstable solid for which IR and NMR spectral data show the same cis-dichloro-trans-phosphine geometry exhibited by the acetylene complexes which places the C=O ligand cis to the imido function. v(C&O) lies at 1925 cm-’ in the IR spectrum indicating significant backbonding to CZO.~’ In comparison, v(C=O) is found at 2006 cm-’ for lWC12(0)(C=O)(PMePh2)2],4 2040 cm- ’ for [ReCl,(NPh)(C=O)(PPh,)],” and 1912 cm- ’ for [W(NPh)(S2CNEt2)2(C=O)].‘o In the 13C{‘H} NMR spectrum the phenylimido ligand ipso- and ortho-carbons show the normal triplet as does the CGO carbon (*J(CP) = 4.78 Hz). EXPERIMENTAL
lYCMNW(PMe3)31, lY~~2WWMeJ’h)~1 and wC12(NCHMe2)(PMe3)3] were prepared by Na/Hg amalgam reduction of [WCl,(NPh)], or [WC14(NCHMe2)12 in the presence of the appropriate phosphine, and [WC13(NPh)(PMe3)2] by reaction of [WC14(NPh)12 with PMe3 in THF.16 Commercial acetylene and carbon monoxide were used as supplied. Petroleum ether (b.p. 4060°C) and benzene were distilled from sodium wire. All distillations and bench-top manipulations were carried out under N, treated to remove oxygen and water 3’ IR spectra were recorded on a PerkinElmer 597 spectrometer and ‘H NMR (400 MHz),
Organoimido complexes of tungsten(IV)
13C(‘H) NMR (100.6 MHz) and 3’P{1H} NMR (162 MHz) spectra on a Bruker AM400 spectrometer. Analytical data were obtained by Professor A. D. Campbel and his associates, University of Otago, New Zealand. Melting points were determined in sealed tubes under N2 on an electrothermal melting point apparatus and are uncorrected. Dichloro (diphenylacetylene) phenylimidobis (trimethylphosphine)tungsten(IV) (1)
Diphenylacetylene (0.5 g, 2.8 mmol) in benzene (30 cm3) was added to dichloro(phenylimido) tris(trimethylphosphine)tungsten(IV) (1 .O g, 1.74 mmol) in benzene (80 cm’) and the mixture was refluxed for 20 h. The solution was filtered and the solvent removed to give a yellow gum which solidified on washing with petroleum ether (50 cm3). Crude yield, 1.0 g (85%). An analytically pure sample was obtained by extracting the crude product with petroleum ether (5 x 100 cm3), combining the extracts, and reducing the volume to give the complex as yellow crystals (0.35 g). IR (Nujol) 176Obm, 1578m, 157Om, 1555w, 1460s 14OOm,1330s 1292m, 1271s 114Ow, 1085w, 1055m, lOlOm, 995w, 975m, 935vs, 904m, 878w, 845m, 836m, 768s 757s 750s 740m, 727s 690s 678s, 672m, 62Ow, 611w, 583w, 564m, 554m, 538w, 527w, 48Ow, 458w, 395w, 373w, 345w, 258m, 255s 230s and 215m cm-‘.
609
(80 cm’) for 18 h. The solution was filtered, the volume reduced to cu 15 cm3 and petroleum ether (100 cm3) added. On standing, colourless crystals of the complex were formed. Yield, 0.36 g (76%). IR (Nujol) 1740bw, 1595w, 1480m, 142Om, 1378m, 1300m, 1275s, 1155w, lllOw, 1068w, 1024w, 95Os, 865m, 785s 778m, 755s 722s 705s 68Ow, 632w, 584m, 565w, 558w, 510m, 475w, 458w, 41Ow, 270s and 245s cm-‘. Acetylenedichlorophenylimidobis (trimethylphosphine) tungsten(W) (4)
Dichloro (phenylimido) tris (trimethylphosphine) tungsten(IV) (0.7 g, 1.2 mmol) was refluxed in benzene (80 cm3) for 16 h under an acetylene atmosphere (balloon). The solution was filtered while hot, and the volume reduced to ca 40 cm3 keeping the solution hot. On standing, yellow microcrystals of the product separated (0.4 g) which were filtered off and washed with petroleum ether (50 cm’). Addition of petroleum ether (50 cm’) to the filtrate gave a further crop of yellow microcrystals (0.2 g). Total yield, 94%. IR (Nujol) 1632w, 1582w, 1482s, 1462s 1423m, 1348s, 1305w, 1294m, 1288m, 1282m, 1173w, 1256w, 1074w, 1028w, 1008w, 996m, 988m, 955~s 868m, 860m, 777m, 768s 75Om, 745s 725w, 700s 683w, 675w, 63Ow, 625w, 56Ow, 538w, 496w, 398w, 355w, 285m, 275s and 240s cm- ‘.
Dichlorobis (dimethy@eny&hosphine) diphenylacetylene(phenylimido)tungsten(Zv (2)
Dichloro (phenylacetylene) phenylimidobis (trimethylphosphine)tungsten(IV) (5)
Diphenylacetylene (0.25 g, 1.4 mmol) and dichlorotris (dimethylphenylphosphine) phenylimidotungsten (IV) (0.9 g, 1.2 mmol) were refluxed in benzene (30 cm3) for 16 h. The solution was filtered, the solvent removed and the residue washed with petroleum ether (100 cm’). Crude yield, 0.8 g (84%). Concentration of the petroleum ether extracts (5 x 100 cm’) gave the complex as yellow crystals (0.2 g). IR (Nujol) 176Ow, 159Ow, 1564w, 1345m, 1294w, 1272w, 1255w, 1134w, 1lOOw, 106Ow, 1018w, 988w, 944m, 922s 910s 904s, 864w, 845w, 83Ow, 795w, 775m, 760s 742s 718m, 690m, 680s 670m, 684s 585w, 57Om, 560m, 544w, 525w, 484m, 455w, 415w, 378w, 335w, 260m and 235m cm-‘.
Phenylacetylene (0.16 g, 1.6 mmol) in benzene (30 cm’) was added to dichloro@henylimido) tris(trimethylphosphine)tungsten(IV) (0.8 g, 1.4 mmol) in benzene (80 cm3) and the mixture was refluxed for 18 h. The solution was filtered and the solvent removed to give a gum which solidified on standing under petroleum ether (100 cm3). Crude yield, 0.74 g (88%). Combination of petroleum ether extracts (3 x 100 cm3) and reduction of the volume gave the complex as yellow crystals (0.3 g). IR(Nujo1) 1731bw, 1595w, 158Ow, 1462m, 1415s 1354s, 1308w, 1285m, 1162~. 1071m, 1028m, 990m, 950~s 857m, 784s 770s 745s 73Ow, 710s 7OOs, 682w, 635w, 628w, 565w, 552w, 538w, 528w, 515w, 398w, 353w, 271s 248m, 230s and 208m cm-‘.
Dichloro (diphenylacetylene) isopropylimidobis (trimethylphosphine)tungsten(IV) (3)
Diphenylacetylene (0.2 g, 1.1 mmol) and dichloro (isopropylimido) tris (trimethylphosphine) tungsten (IV) (0.4 g, 0.74 mmol) were refluxed in benzene
Dichloro(bopropylim~o)phenylacetyle~b~(trimethylphosphine)tungsten(IV) (6)
Dichloro(isopropylimido)tris(trimethylphosphine) tungsten(IV) (0.9 g, 1.7 mmol) and phenylacetyl-
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A. J. NIELSON
ene (0.2 g, 2.0 mmol) in benzene (100 cm3) were re-
fluxed for 16 h. The solution was filtered, the volume reduced to ca 25 cm3 and petroleum ether (100 cm’) added, giving the complex as a yellow noncrystalline solid which was filtered off, washed with petroleum ether (30 cm’) and dried in vacua. Yield, 0.53 g (55%). IR (Nujol) 173Om, 159Ow, 1475s, 1412s, 1350m, 13OOm, 1268s, 1165w, 1145w, lllOw, 1068w, 102Ow, 95Ovs, 858m, 8OOw,76Os, 75Os, 735s, 704s, 675m, 630m, 618w, 565w, 52Ow, 345w, 265s and 220m cm-‘. Carbonyldichloro (phenylimido) bis (trimethylphosphine)tungsten(IV) (7)
Trichloro (phenylimido) bis(trimethylphosphine) tungsten(V) (1 .O g, 1.9 mmol) in benzene (100 cm3) was reduced with Na/Hg amalgam (50 mg Na, 2.2 mmol; 40 g Hg) under carbon monoxide (20 p.s.i.) for 5 h. The solution was filtered and the solvent removed to give a purplebrown crystalline solid which was extracted with warm petroleum ether (5 x 200 cm3). The combined extracts were filtered and the solvent reduced to ca 5 cm3 giving the complex as a purple crystalline solid. Yield, 0.7 g (70%). IR (Nujol) 1925s, 1464s 1418s, 1345s, 1305m, 1284s 116Ow, 107Ow, 1025w, 945s 860m, 855m, 775s, 742s, 695s, 670m, 570m, 558m, 46Ow, 38Ow, 34Ow, 305s and 260s cm-‘. REFERENCES 1. W. A. Nugent and J. M. Mayer, Metal-Ligand Multiple Bona!s. Wiley Interscience, New York (1988). 2. E. A. Maatta and R. A. D. Wentworth, Znorg. Chem. 1979, 18, 524. 3. W. E. Newton, J. W. McDonald, J. L. Corbin, L. Ricard and R. Weiss, Znorg. Chem. 1980, 19, 1997. 4. F.-M. Su, C. Cooper, S. J. Geib, A. L. Rheingold and J. M. Mayer, J. Am. Chem. Sot. 1986,108,3545. 5. N. G. Bokiy, Yu. V. Gatilov, Yu. T. Struchkov and N. A. Ustynyuk, J. Organomet. Chem. 1973,54,213. 6. H. G. Alt and H. I. Hayen, J. Organomet. Chem. 1986,316, 105. 7. J. R. Morrow, T. L. Tonker and J. L. Templeton, Organometallics 1985,4, 745. 8. W. A. Nugent and B. L. Haymore, Coord. Chem. Rev. 1980, 31, 123.
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