Organometallics 1996,14, 4236-4241
4236
Stoichiometric Homologation of 1,3=Butadieneby Reaction with the Iridium Methylene Complex Ir=CH2[N(SiMe2CHzPPh2)2] Michael D. Fryzuk,* Xiaoliang Gao, and Steven J. Rettig' Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, Canada V6T 121 Received April 12, 1995@ The reaction of the iridium methylene complex IFCHZ[N(S~M~ZCHZPP~Z)ZI with 1,3butadiene leads to the formation of a new complex with the formula Ir(CsHdN(SiMezCH2PPh2)2] in which 1 equiv of butadiene has been incorporated. By a series of NMR experiments, the structure was established as containing a a-y3-pentenyl unit. The X-ray crystal structure confirms the stereochemistry of the hydrocarbyl unit as being anti-exo, with the tridentate ancillary ligand adopting the facial orientation. Labeling studies indicate that the formation is diastereoselective as a result of the orientation of the incoming double bond in the early stages of the reaction mechanism. Scheme 1
Introduction The reaction of metal-alkylidene complexes with 1,3butadiene in an olefin metathesis type reaction has not been examined in detai11-3 either because the reaction can be considered as nonproductive after one or two cycles or due to the possibility that a conjugated diene can act as a catalyst p ~ i s o n .However, ~ cyclopropanation of conjugated dienes by a metal-catalyzed diazoalkane addition is an important reaction leading to the formation of vinylcycl~propanes~-~ that can be further elaborated8 and are important in their own right in natural product chemistry. As shown below in Scheme 1for the case of a transition-metal methylene complex reacting with 1,3-butadiene, both the olefin metathesis (path a) and the cyclopropanation (path b) reactions can be envisioned as proceeding through a common vinylsubstituted metallacyclobutanetype inte~mediate.~ Such an intermediate has the further option of rearranging via a ,&elimination sequence (path c ) to ultimately result in homologation. All of these pathways in Scheme 1 have their origin in the reaction of olefins with a methylene unit attached to a metal to generate a metallacyclobutane. For group 8 metals, numerous studies have documented the synthesis and reactivity of metallacyclobutane derivatives.lOJ1 However, the intermediate metallacyclobutane formed from 1,3-butadiene has yet another, so far unrecognized pathway for rearrangement; because there is a metal-carbon a-bond with a proximate &double Professional Officer: UBC Crystal Structure Service. @Abstractpublished in Advance ACS Abstracts, July 15, 1995. (1)Ivin, K.J . Olefin Metathesis; Academic Press: New York, 1983. (2) Dragutan, V.;Balaban, A. T.; Dimonie, M. Olefin Metathesis and Ring-Opening Polymerization of Cycloolefins; Wiley: Bucharest, 1985. (3) Streck, R. J . Mol. Catal. 1992, 76, 359. (4) Zerpner, D.; Holtrup, W.; Streck, R. J . Mol. Catal. 1986,36, 153. (5) Aratani, T. Pure Appl. Chem. 1985, 57, 1838. (6) Doyle, M.P. Chem. Rev. 1986, 86, 919. (7) Green, J.; Sinn, E.; Woodward, S.; Butcher, R. Polyhedron 1993, 12, 991. (8) March, J. Advanced Organic Chemistry; Wiley: Toronto, 1985; p 1019. (9)Wulff, W. D.;Yang, D. C.; Murray, C . K. Pure Appl. Chem. 1988, 60,137. (10)Puddephatt, R. J. Coord. Chem. Rev. 1980,33, 149. (11) Jennings, P. W.; Johnson, L. L. Chem. Rev. 1994,94, 2241. +
H 'C=CH2 LnM=CH2
+ H2C-C
/
H'
/CH=CH*
LnM=CH
a
+ H&=CH2
I C
bond, one could anticipate a ring expansion to form a six-membered ring (eq 1). In this paper we document
ul I HC-CHz PI
HzC=CH
-
I
"'"\
HC=CH
\
/""'
(1)
a variant of such a transformation for the reaction of an iridium methylene complex with 1,3-butadiene. We have previously shown that the 16-electron iridium(1) methylene complex I~=CHZ[N(S~M~ZCHZPP~Z)ZI (1) is reactive to a variety of small molecules and unsaturated substrates such as allene and certain 01efins.l~-'~Undoubtedly, it is the coordinative unsaturation at the metal center in concert with the reactive (12) Fryzuk, M. D.; Joshi, K.; Rettig, S. J . Organometallics 1991,
10, 1642.
(13) Fryzuk, M.D.; Gao, X.; Joshi, K.; MacNeil, P. A,; Massey, R. L. J.Am. Chem. SOC.1993, 115, 10581.
0276-733319512314-4236$09.00/00 1995 American Chemical Society
Stoichiometric Homologation of 1,3-Butadiene
Organometallics, Vol. 14,No.9,1995 4237
Ir=CH2 fragment that renders this methylene derivative susceptible to further transformations. However, the tridentate ancillary ligand is apparently able t o moderate the reactivity somewhat since the starting methylene 1 is remarkably thermally stable; by comparison, two related 18-electron methylene complexes of iridium, Ir=CH2(CO)I(PPh3)2and (q5-C5Me5)Ir=CH2(PMe3), are stable only to -50 and -40 "C, respectively.15J6 An additional consequence of the presence of the ancillary tridentate ligand of 1 is that the stereochemistry of the resulting products reflects considerable inherent diastereoselectivity. The reaction of 1 with 1,3-butadiene also displays complete diastereoselectivity in the formation of the l-a,3-y3-pentenylunit attached to iridium.
Results and Discussion 1,3-Butadiene reacts with the methylene complex 1 over a period of 1h at room temperature t o give a single product by both lH and 31P{1H} NMR spectroscopies. Elemental analyses are consistent with the formula Ir(CgH8)[N(SiMezCHzPPh2)21, 2; in other words, only 1 equiv of 1,3-butadiene is incorporated into the methylene complex 1teq 2).
I ~ = C H ~ [ N ( S ~ M ~ ~ C H +~ P P ~ ~ ) Z ] 1
toluene
I
HzC=C
H '
L
The 31P{lH} NMR spectrum of 2 shows that there are two doublets that are assigned t o inequivalent phosphines coupled together with a coupling constant of 7.3 Hz, the latter typical of a cis-disposition of the phosphorus donors of the tridentate ligand. Unlike the reaction of olefins with 1 which generates allyl-hydride complexes, no hydride signal in the lH NMR spectrum of complex 2 could be located. Instead, the resonances of all eight inequivalent protons on the C5H8 unit were apparent and could be assigned on the basis of decoupling and NOE experiments. The lack of symmetry of the C5H8 unit was also mirrored in the ancillary tridentate ligand in that all four silyl methyl groups and all four backbone methylene protons were found to be inequivalent. In the 13C{'H} NMR spectrum of 2 there were observed five peaks consistent with the five inequivalent carbons of the C5H8 unit of which three resonances were typical of an allyllic unit: a singlet and two doublets at 108.35, 44.16, and 54.90 ppm, respectively, with the latter two resonances coupled t o phosphorus (d, 2 J ~ p= 35.1 Hz; d, 2 J ~ p= 23.5 Hz); the remaining two resonances were observed at 28.01 (s) and -37.29 (s ppm). A structure that is consistent with the spectroscopic parameters is shown below. The connectivity is based on NOE experiments; these NOE spectra are shown in Figure 1. The cis-disposition of the phosphorus donors (14)Fwzuk, M. D.; Gao, X.; Rettia, - S . J. J . Am. Chem. Soc. 1995, 117, 3106: (15) Clark, G. R.; Roper, W. R.; Wright, A. H. J.Organomet. Chem. 1984,273, C17. (16) Klein, D. P.;Bergman, R. G. J . Am. Chem. SOC.1989,111,3079.
Figure 1. NOE difference spectra for Ir(a-r/3-C&)[N(SiMe2CH2PPh&] (2): (i) normal 400 MHz IH NMR spectrum from -1.5 to 5.0 ppm; (ii) irradiation of peak A, (iii) irradiation of peak B; (iv) irradiation of peak C; (v) irradiation of peak D; (vi) irradiation of peak E; (vii) irradiation of peak F; (viii) irradiation of peak G; and (ix) irradiation of peak H. See also Chart 1. necessarily puts the tridentate ligand into a facial orientation leaving the remaining three sites of the presumed octahedral Ir center for the C5H8 unit. The two upfield multiplets at -0.93 and 0.84 ppm in the 'H NMR spectrum are probably due t o the protons of the carbon directly attached to the iridium via a 0-bond; in other words, these two resonances belong to H1/H2 attached to C,. This was confirmed by repeating the reaction with the deuterium labeled methylene complex Ir=CD2[N(SiMe2CHzPPh2)21(d2-1) which gave rise t o d2-2 but with these two upfield resonances absent in the IH NMR spectrum.
2
4238 Organometallics, Vol. 14,No.9,1995
Fryzuk et al. Scheme 2
C16
H
\
,C=CH2
C15
HzC=C'
H'
-1
Figure 2. Molecular structure and numbering scheme for
Ir(a-q3-CjHs)[N(SiMe&H2PPh2)21 (2). Irradiation of the most upfield resonance, peak A, and resulted in enhancement of peaks B (25%),D (ll%), E (7%),while irradiation of peak B produced enhancements at peaks A (23%)and C(8%). This allows a preliminary assignment of HI to peak B and H2 to peak A since the latter would be expected, after irradiation, to transfer magnetization to both I& (peak E) and anti proton H8 (peak D), attached to carbon C, at the other end of the C5H8 moiety. This also suggests that peak C is due to H3 since it is enhanced by the vicinal HI. Irradiation of peak C (H3) results in enhancements in peaks E (H4, 29%), B (HI, 5%), and H (7%); the enhancement of peak H at 4.11 ppm allows its assignment to Hj, the syn proton attached to carbon C,. When peak D (H8) is irradiated, enhancements at peaks F (16%),A (H2,6%),and E (H4,2%);assignment of peak F t o the syn proton H7 attached to the same carbon as H8 is consistent with this particular experiment. At this point, the only peak not assigned is peak G at 4.02 ppm, which, by default, must be due t o He, the central proton of the allyllic unit. Confirmation of this was complicated by the proximity of the resonances due to the syn protons Hj and H7 (peaks H and F, respectively), however, one can observe that irradiation of peak F (H7) does result in enhancement of peak G, the central proton resonance. In addition, irradiation of peak G does show enhancements to both peaks F and H, as expected. More importantly however, irradiation of peak G (He) produced enhancements in two of the four silyl methyl resonances. This latter result allows the stereochemistry of the v3-allylunit to be assigned as exo since the central carbon of this moiety points toward the disilylamido portion of the tridentate ancillary ligand. In fact, in keeping with nomenclature previously established for
the reaction of the methylene complex 1 with olefins,14 the stereochemistry of the C5H8 unit is described as anti-exo. Interestingly, irradiation of both syn protons H5 and H7 in turn produces enhancements of the appropriate proximate silyl methyl resonances, as expected on the basis of the proposed structure. Crystal StructureAnalysis of Ir(a-q3-C&)[N(SiMezCHzPPh2)21. The stereochemistry determined by NMR spectroscopy was confirmed by single-crystal X-ray diffraction. The molecular structure and numbering scheme are shown in Figure 2; selected bond lengths and bond angles appear in Table 3. The facial orientation of the tridentate ligand is evident and is characterized by a Pl-Ir-P2 bond angle of 107.74(8)",with P1Ir-N and P2-Ir-N being 87.1(1) and 83.3(2)",respectively. The C5H8 unit is bound to the iridium in an antiexo configuration;there is a direct iridium-carbon bond to C31 which is trans to the amide donor with N-IrC31 being 174.4(3)"and an Ir-C31 bond length of 2.108(8) A. This carbon is attached to C32, which is the anti substituent to the allyl unit; this carbon lies 20" out of the plane defined by the three carbons of the allyl moiety, C33, C34, and C35. The angle subtended by these carbons, C33-C34-C35, is 122.8(9)",close to the expected 120"for an allyl unit. The bond lengths within the allyl unit are typical of such systems: C33-C34, 1.36(1)A;C34-C35,1.40(1) A. The distances between the allyl carbons and the iridium are as follows: IrC33 2.241(8)A;Ir-C34,2.166(8) A;and Ir-C35,2.224(8) these distances are essentially identical to those found for the related allyl-hydride ~omp1exes.l~ Mechanism of Formation. As mentioned in the introduction, We reaction of certain electron deficient olefins with the methylene complex 1 results in the diastereoselective formation of allyl hydride derivat i v e ~ . 'As ~ described here, 1,3-butadiene reacts with 1
A;
Stoichiometric Homologation of 1,3-Butadiene
Organometallics, Vol. 14, No. 9, 1995 4239
Table 1. CrvstalloaaDhic Dataa I~(C~HB)[N(S~M~~CH~PP~~)
Chart 1
compd formula fw color, habit cryst syst space group a,A b, A
NOE Experiment
c,
A
Po v, A3 z IH NMRn
6
P(CsH5)z Hi H2 H3 H4 H5 Hs H7 Hs SiCHzP SiCHzP SiCHzP SiCHzP SiMe SiMe SiMe SiMe
6.6-7.8 (m) 0.84 (m) -0.93 (m) 1.26 (m) 2.85 (m) 4.11 (t) 4.02 (m) 3.90 (m) 2.11 (m) 2.20 (dd) 2.08 (t) 1.95 (t) 1.91 (t) 0.44 (s) 0.32 (s) 0.27 (s) 0.25 (s)
1H{31P}b
ecalc, glcm3 F(OO0) p , cm-I crystal size, mm3 transmissn factors scan type scan range, deg in o scan speed, deglmin data collected 2OmaX,deg crystal decay, % tot. no. of reflns tot. no. of unique reflns
coupling constants
Rmerge
no. of reflns with Z z 3dZ) no. of variables
R Rw
a C&, 400 MHz. Simplification of the multiplet pattern upon broad-band decoupling.
to produce exclusively the anti-exo isomer of 2. On the basis of the mechanism previously suggested for the olefin reactions, a similar mechanism can be envisioned as shown in Scheme 2; to take into account the labeling experiment, the dideuteriated methylene complex dz-1 is used in the scheme. The first step involves coordination of the 1,3-butadiene to the methylene complex 1 via v2 interaction t o form intermediate A in which the coordinated end of the diene lies perpendicular to the Ir=C n-system. In agreement with semiempirical MO calculation^,^^ such an approach allows overlap of the HOMO of a bent metal fragment with the appropriate n* orbital of the coordinated double bond. Subsequent carbon-carbon bond formation occurs to generate B, which has a highly puckered iridacyclobutane unit and a vinyl substituent on an a-carbon. This presumably can undergo ring expansion by using the exocyclic double bond to form C; counterclockwise rotation of the allyllic unit in C will generate the observed product 2. The carbon-carbon bond formation to generate B can be considered to go via another possible intermediate shown below as D; however, this puts the exocyclic vinyl group at the central carbon of the puckered iridacyclobutane and thus cannot ring expand.
gof max Mu (final cycle residual density, e / l 3
C35H44IrNP2Si2 789.08 colorless, plate monoclinic P21lc 10.710(3) 18.261(4) 17.976(4) 96.81(2) 3491(2) 4 1.501 1584 39.92 0.05 x 0.20 x 0.35 0.68-1.00 w-28 1.10 0.35 tan 8 16 (up to 8 rescans) +h,+k,il 60 negligible 10 777 10 479 0.070 3684 371 0.035 0.027 1.28 0.01 -0.71 to 0.57 (near Ir)
+
Temperature, 294 K Rigaku AFC6S diffractometer; Mo K a radiation ( I = 0.710 69 A); graphite monochromator; takeoff angle, 6.0”;aperature, 6.0 x 6.0 mm2 at a distance of 285 mm from the crystal; stationary background counts at each end of the scan (scad background time ratio 2:1, up to 8 rescans); u2(F)= [S2(C 4B)Y Lp2 (S = scan rate, C = scan count, B = normalized background count); function minimized, Xw(lFol - IFc1)2where w = 4F021u2(Fo2), R = ZllFol - IFcllEIFol, R, = (Xw(lFoI - IFcl)2EwIFo12)1’2, and gof = [Zw(lFol - IFci)2/(m- n)]l”. Values given for R, R,, and gof are based on those reflections with Z z 3dZ). (I
+
H
exo configuration. In a formal sense, this represents a one-carbon homologation of 1,3-butadiene, albeit bound to a metal complex. The stability of this hydrocarbyl unit attached to iridium is remarkable and might explain why certain alkylidene-containing catalysts are poisoned by the presence of conjugated diene^.^
Conclusions
Experimental Section
The results of this study show that the iridium can methylene compound 1r=CH~[N(SiMezCHzPPhz)zl react with 1,3-butadiene to undergo a stoichiometric carbon-carbon bond formation. This reaction probably involves an initial formation of a vinyl-substituted iridacyclobutane unit which undergoes a diastereoselective expansion t o generate a l-a,3-v3-pentenyl unit bound to the I~[N(S~M~ZCHZPP~Z)ZI fragment in an anti-
General Procedures. All experimental procedures were ~ preparation of identical to that previously d e ~ c r i b e d . ’ The Ir=CH2[N(SiMezCH2PPh2)2]follows that of t h e improved procedure described in t h e 1 i t e r a t ~ r e . l ~ Preparation of Ir(a-rlS-CsHe)[N(SiMe~CHSPhz)zl. To a toluene solution (15 mL) of t h e methylene complex 1 (90 mg, ~~~
~
(17)Fryzuk, M. D.; Huang, L.; McManus, N. T.; Paglia, P.; Rettig, S. J.; White, G. S. Organometallics 1992, 11, 2979.
Fryzuk et al.
4240 Organometallics, Vol. 14, No. 9, 1995
Table 2. Final Atomic Coordinates (Fractional) and Be, atom Ir(1) P(1) P(2) Si(1) Si(2) N(1) C(1) C(2) C(3) C(4) C(5) C(6) C(7) C(8) C(9) C(10) C(11) 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) C(28) C(29) C(30) C(31) C(32) C(33) C(34) C(35)
X
0.36934(3) 0.2840(2) 0.3798(2) 0.5668(2) 0.6496(2) 0.5541(5) 0.4083(7) 0.5432(7) 0.6046(8) 0.6848(8) 0.7521(10) 0.7622(9) 0.1637(7) 0.1305(8) 0.0348(9) -0.0276(9) 0.0058(8) 0.1011(8) 0.1998(8) 0.2627(8) 0.1989(10) 0.0731(10) 0.0077(9) 0.0705(9) 0.3438(7) 0.3994(8) 0.3759(9) 0.2988(10) 0.2459(9) 0.2664(8) 0.2896(9) 0.3460(9) 0.2752(13) 0.1484(12) 0.0895(9) 0.1616(9) 0.2003(8) 0.2276(10) 0.3618(9) 0.4589(9) 0.4424(8)
Y
0.27027(2) 0.30809(11) 0.14533(10) 0.32357(12) 0.19556(13) 0.2622(3) 0.3235(4) 0.1223(4) 0.4188(4) 0.3031(5) 0.1505(5)
0.2264(6) 0.2534(4) 0.2690(5) 0.2315(6) 0.1774(6) 0.1592(5) 0.1983(4) 0.3961(4) 0.4628(4) 0.5289(4) 0.5286(5) 0.4641(6) 0.3974(5) 0.0935(4) 0.1161(4) 0.0810(5) 0.0204(5) -0.0031(4) 0.0323(4) 0.0971(4) 0.0559(4) 0.0252(5) 0.0344(5) 0.0740(5) 0.1044(5) 0.2887(4) 0.3663(5) 0.3793(5) 0.3386(5) 0.2700(5)
z
0.50062(2) 0.38449(11) 0.49894(13) 0.38467(13) 0.4924(2) 0.4534(3) 0.3252(4) 0.5269(4) 0.4206(5) 0.3180(5) 0.4294(6) 0.5763(6) 0.3282(4) 0.2536(5) 0.2118(5) 0.2450(6) 0.3188(6) 0.3609(4) 0.3846(4) 0.3849(4) 0.3891(5) 0.3943(6) 0.3940(6) 0.3883(5) 0.4119(4) 0.3499(5) 0.2822(5) 0.2751(5) 0.3365(6) 0.4039(5) 0.5644(4) 0.6239(5) 0.6752(5) 0.6679(6) 0.6093(6) 0.5590(5) 0.5470(5) 0.5732(5) 0.5571(5) 0.5900(4) 0.6217(4)
Be, 2.91(1) 3.0(1) 3.34(9) 3.7(1) 4.8(1) 3.2(3) 3.5(4) 4.3(4) 5.2(5) 5.8(5) 8.5(7) 8.6(6) 3.3(4) 5.4(4) 6.8(5) 6.7(6) 5.4(5) 4.1(4) 3.7(4) 4.1(4) 5.7(5) 6.4(6) 6.4(6) 5.2(5) 3.3(4) 4.5(4) 5.4(5) 5.8(5) 5.4(5) 4.2(4) 3.9(4) 5.0(5) 6.9(6) 6.8(6) 6.7(6) 5.8(5) 4.7(4) 6.3(6) 5.0(5) 4.7(5) 5.8(4)
Table 3. Bond Lengths (A)and Bond Angles (deg) with Estimated Standard Deviations Ir(l)-P(l) Ir(l)-P(2) Ir(l)-N(l) Ir(l)-C(31) Ir(l)-C(33) Ir(l)-C(34) Ir(l)-C(35) P(l)-C(l) P(1)-C(7) P( 1)- C(13) P(2)-C(2) P(2)-C(19) P(2)-C(25) Si(1)-N( 1) Si(1)- C(1) Si(l)-C(3) Si(l)-C(4) Si(P)-N(l) Si(2)-C(2) Si(2)-C(5) Si(2)-C(6) C(7)-C(8) C(7)-C(12) C(8)-C(9) C(9)-C(lO)
Bond Lengths 2.284(2) C(lO)-C(ll) 2.285(2) C(ll)-C(l2) 2.249(5) C(13)-C(14) 2.108(8) C(13)-C(18) 2.241(8) C(14)-C(15) 2.166(8) C(15)-C(16) 2.224(8) C(16)-C(17) 1.823(7) C(17)-C(18) 1.836(7) C(19)-C(20) 1.843(7) C(19)-C(24) 1.812(8) C(20)-C(21) 1.831(8) C(21)-C(22) 1.834(8) C(22)-C(23) 1.686(6) C(23)-C(24) 1.895(8) C(25)-C(26) 1.885(8) C(25)-C(30) 1.880(8) C(26)-C(27) 1.688(6) C(27)-C(28) 1.908(8) C(28)-C(29) 1.860(9) C(29)-C(30) 1.90(1) C(31)-C(32) 1.376(9) C(32)-C(33) 1.379(9) C(33)-C(34) 1.38(1) C(34)-C(35) 1.37(1)
1.37(1) 1.39(1) 1.392(9) 1.40(1) 1.39(1) 1.36(1) 1.37(1) 1.40(1) 1.39(1) 1.39(1) 1.37(1) 1.38(1) 1.37(1) 1.37(1) 1.39(1) 1.37(1) 1.38(1) 1.36(1) 1.37(1) 1.37(1) 1.51(1)
1.52(1) 1.36(1) 1.40(1)
Bond Angles P(l)-Ir(l)-P(2) 107.74(8) Ir(U-N(U-Si(2) 114.0(3) P(l)-Ir(l)-N(l) 87.1(1) Si(l)-N(l)-Si(2) 133.4(3) P(l)-Ir(l)-C(31) 92.5(2) P(l)-C(l)-Si(l) 109.8(4) P(l)-Ir(l)-C(33) 96.5(2) P(2)-C(2)-Si(2) 110.0(4) P(l)-Ir(l)-C(34) 126.7(3) P(l)-C(7)-C(8) 120.5(6) P(l)-Ir(l)-C(35) 162.0(2) P(l)-C(7)-C(12) 120.5(6) P(2)-Ir(l)-N(l) 83.3(2) C(8)-C(7)-C(12) 119.0(7) P(2)-1r(l)-C(31) 102.1(2) C(7)-C(8)-C(9) 121.2(8) P(2)-Ir(l)-C(33) 153.9(2) C(8)-C(9)-C(lO) 119.4(9) P(2)-Ir(l)-C(34) 124.5(3) C(9)-C(lO)-C(ll) 120.7(9) P(2)-Ir(l)-C(35) 89.9(2) C(lO)-C(ll)-C(l2) 119.4(9) 120.3(8) N(l)-Ir(l)-C(31) 174.4(3) C(7)-C(l2)-C(ll) N(l)-Ir(l)-C(33) 108.0(3) P(l)-C(l3)-C(l4) 121.8(7) 120.2(6) N(l)-Ir(l)-C(34) 89.2(3) P(l)-C(l3)-C(l8) C(14)-C(13)-C(18) 117.9(7) 98.4(3) N(l)-Ir(l)-C(35) 121.2(8) 66.5(3) C(13)-C(14)-C(15) C(3l)-Ir(l)-C(33) a B, = (8/3)fi2~~U,Ja,aJ(a,.a,). C(14)-C(15)-C(16) 119.8(9) C(3l)-Ir(l)-C(34) 86.6(3) C(15)-C(16)-C(17) 120.9(9) 80.3(3) C(3l)-Ir(l)-C(35) 0.1124 mmol) was charged 1,3-butadiene (15 mL, 1atm). The 119.9(9) 35.8(3) C(16)-C(17)-C(18) C(33)-Ir(l)-C(34) purple color gradually faded, and after 1 h a light yellow C(33)-Ir(l)-C(35) 65.5(3) C(13)-C(18)-C(17) 120.3(8) solution formed. The solution was stirred for 1 more h and 117.8(6) 37.1(3) P(2)-C(19)-C(20) C(34)-Ir(l)-C(35) was pumped to dryness. Recrystallization of the residue in 124.6(6) Ir(l)-P(l)-C(l) 109.9(3) P(2)-C(19)-C(24) hexanes gave colorless crystals. Slow evaporation of the 121.2(2) C(2O)-C(19)-C(24) 117.7(7) Ir(l)-P(l)-C(7) 113.9(2) C(19)-C(2O)-C(21) 121.6(8) Ir(l)-P(l)-C(l3) mother liquor to almost dryness gave a second crop of crystals. C(l)-P(l)-C(7) 106.0(3) C(2O)-C(21)-C(22) 120.0(8) The two crops of crystals were washed with cold hexanes (-30 118.6(8) 104.9(3) C(21)-C(22)-C(23) C(l)-P(l)-C(l3) "C, 2 x 2 mL) and were dried under vacuum. The yield of 121.9(8) 99.4(3) C(22)-C(23)-C(24) this compound was 76 mg, 86%. Anal. Calcd for C ~ S H ~ ~ I ~ N P ZC(7)-P(l)-C(13) Ir(l)-P(2)-C(2) 108.0(2) C(19)-C(24)-C(23) 120.2(8) H, 5.70; N, C, 53.64; Siz: C, 53.28; H, 5.62; N, 1.77. Found: Ir(l)-P(2)-C(l9) 121.5(2) P(2)-C(25)-C(26) 122.8(7) 1.85. 31P{1H} NMR (500 MHz, CsDs, 6): -5.54 (d, 'Jpp 7.3 Ir(l)-P(2)-C(25) 116.1(3) P(2)-C(25)-C(30) 120.4(7) Hz), -8.42 (d, 'Jpp = 7.3 Hz). l3C{'H) NMR (CfjDs, 400 MHz, C(2)-P(2)-C(19) 102.5(3) C(26)-C(25)-C(30) 116.6(8) 6): 5.32 (s, SiMe); 5.36 (s, SiMe); 5.92 (s, SiMe), 9.04 (s, SiMe); C(2)-P(2)-C(25) 106.0(4) C(25)-C(26)-C(27) 120.9(9) C(19)-P(2)-C(25) 103.1(3) C(26)-C(27)-C(28) 120(1) 24.26 (d, lJpc = 16.4 Hz, SiCHZP); 30.10 (d, lJpc = 22.3 Hz, N(l)-Si(l)-C(l) 105.6(3) C(27)-C(28)-C(29) 120.2(9) SiCHZP); a-v3-C5H8ligand, 44.16 (d, 2 J ~ = p 35.1 Hz, Cd; 108.35 N(l)-Si(l)-C(3) 113.3(3) C(28)-C(29)-C(30) 119(1) (S, Cd); 54.90 (d, 'Jcp = 23.5 Hz,Cd; 28.01 (S, Cb); -37.29 (S, N(l)-Si(l)-C(4) 117.0(3) C(25)-C(3O)-C(29) 123.3(9) Ca); PPhz, 127-133 (overlapping). See also Chart 1. C(l)-Si(l)-C(3) 109.9(3) Ir(l)-C(3l)-C(32) 97.4(5) X-ray Crystallographic A n a l y s i s of Ir(C&d[N(SiMezC(l)-Si(l)-C(4) 105.4(4) C(31)-C(32)-C(33) 103.9(7) CH2PPhz)zI. Crystallographic data appear in Table 1. The C(3)-Si(l)-C(4) 105.3(4) Ir(l)-C(33)-C(32) 91.9(5) final unit-cell parameters were obtained by least-squares N(l)-Si(2)-C(2) 106.6(3) Ir(l)-C(33)-C(34) 69.1(5) refinement on the setting angles for 25 reflections with 2 8 = N(l)-Si(2)-C(5) 116.0(4) C(32)-C(33)-C(34) 121.7(9) 8.7-15.5". The intensities of three standard reflections, N( l)-Si(2)-C(6) 114.3(4) Ir( l)-C(34)-C(33) 75.1(5) C(2)-Si(2)-C(5) 107.8(4) Ir(l)-C(34)-C(35) 73.7(5) measured every 200 reflections throughout the data collection, C(2)-Si(2)-C(6) 107.3(4) C(33)-C(34)-C(35) 122.8(9) showed only small random fluctuations. The d a t a were C(5)-Si(2)-C(6) 104.5(5) Ir(l)-C(35)-C(34) 69.2(4) processed18 and corrected for Lorentz and polarization effects Ir(l)-N(l)-Si(l) 112.6(3) and absorption (empirical, based on azimuthal scans for three reflections). The structure was solved by heavy atom methods, the coordinates of the Ir, P, and Si atoms being determined from (18) TEXSANI TEXRAY Structure Analysis Package, Version 5.1; the Patterson function and those of the remaining nonMolecular Structure Corporation: The Woodlands, TX,1985.
Stoichiometric Homologation of 1,3-Butadiene hydrogen atoms from subsequent difference Fourier syntheses. All non-hydrogen atoms were refined with anisotropic thermal parameters. Hydrogen atoms were fixed in idealized positions (C-H = 0.98 A, BH = 1.2Bbonded A secondary extinction correction (Zachariasen isotropic type I) was applied, the final value of the extinction coefficient being 1.37 (6) x Neutral atom scattering factors for all atoms and anomalous dispersion corrections for the non-hydrogen atoms were taken from the International Tables for X-Ray Cry~tallography.'~ Final atomic coordinates and equivalent isotropic thermal parameters are given in Table 2, and selected bond lengths and angles appear in Table 3. Hydrogen atom parameters, anisotropic thermal parameters, complete tables of bond (19)International Tables for X-Ray Crystallography; Kynoch Press: Birmingham, England, 1974;Vol. IV, pp 99-102, 149-150.
Organometallics, Vol. 14,No. 9, 1995 4241 lengths and bond angles, torsion angles, intermolecular contacts, and least-squares planes are included as supporting information.
Acknowledgment. Financial support was provided by NSERC of Canada. We thank Johnson-Matthey for the generous loan of iridium salts. Supporting InformationAvailable: Tables of hydrogen atom parameters, anisotropic thermal parameters, all bond lengths and bond angles, torsion angles, intermolecular contacts, and least-squares planes (15 pages). Ordering information is given on any current masthead page. OM950266S
