3659
Organometallics 1992,11, 3659-3664
Synthesis, Molecular Structure, and Reactivity of the Octahedral Iridium( III)Compound [ IrH(q1,q3-C,H12)(dppm)] (dppm = Bis(diphenylphosphino)methane) Miguel A. Esteruelas,t Montserrat Olivht Luis A. Oro, 4 p t Michael Schulz,s Eduardo Helmut Werner4-$
and
Departamnto de Chimica Inorghica, Instituto de Ciencia de Materleles de AraNn, UniversMad de Zaragoza, CSIC, 50009 Zaragoza, Spain, and Institut fiir Anorganische Chemie, UniversMt Wiirzburg, Am Hubiand, W-8700 Wiirzburg, Germany Received March 25, 1992
The complex [Ir(c(-OCH3)(q4-1,5-COD)I, (1) reacts in methanol with dppm (bis(diphenylphosphin0)methane) to give [IrH(q1,q3-C8Hl2)(dppm)] (2). The molecular structure of this compound has been determined by X-ray investigation. 2 crystallizes in the space group ml/n with a = 10.406 (1)A, b = 17.703 (3) A, c = 15.894 (2) A, and 8 = 102.15 ( 1 ) O . The coordination geometry about the iridium center can be rationalized as a distorted octahedron with the phosphorus atoms of the dppm ligand, one terminal allyl carbon atom, and the C-Ir carbon atom forming the equatorial plane. The apical positions are occupied by the other terminal aUyl carbon atom, and the hydride ligand. The reaction of [Irb-OCD3)(q4-1,5-COD)I2 ( 1-d6)with dppm in methanol-d4leads to 2-d3. Two of the three deuterium atoms of 2-d3 are located on the methylene group of the diphosphine ligand, and the other on one of the two carbon atoms bonded to the C-Ir carbon atom of the carbocyclic ligand. On the basis of this result and other considerations, a mechanism for the formation of 2 is proposed. 2 is formed via the intermediate [IrH(q4-1,5-COD)(dppm)] which evolves to [Ir(.13-C$rlJ(dppm)] by hydride transfer from the metal to an olefh group of the coordinated diolefin, and subsequent double-bond migration. The last step is the intramolecular C-H (sp3)activation of one of the two C-H bonds on the carbon atom that is equidistant from the terminal allyl atoms of the 2 reacts with electrophiles and nucleophiles; the reaction with carbocyclic ligand of [Ir(q3-CBH13)(dppm). (13), while in the presence of CO and P(OMeI3the HBF4 leads to cis-[IrH2(q4-1,5-COD)(dppm)]BF4 compounds [Ir(q1,q2-CBH13)(dppm)L] (L = CO (14), P(OMeI3(15)) are obtained.
Introduction The reaction of [ C O ( ~ ~ - C ~ H ~ ~ ) ( ~with ~ ~ -HBF4* ~,~-COD)] EhO and arene ligands results in the formation of [CoWe have previously reported that in the presence of (q1,q3-CBH12)(q6-arene)]+ complexes. The arene ligands in potassium hydroxide the cationic complexes [Rh(q4these compounds are easily displaced by acetonitrile to give NBD)(PPh&l+, [Rh(q4-NBD)L2l+,[Irh4-TFB)(PPh3)21+, [Co(q1,q3-CBH12) (CH,CN),]+, which is a versatile starting and [Ir(q4-TFB)L2]+(NBD = 2,5-norbomadiene, TFB = material for the synthesis of neutral cobalt compounds tetrafluorobenzobarrelene; L2 = 1,3-bis(diphenylwith the q1,q3-CsH12ligand. Complexes containing such phosphino)propane (dppp), 1,2-bis(diphenylphosphino)a C8 ring linked by a a-bond and a q3-enyl group to a ethane (dppe), and bis(dipheny1phosphino)methane central atom have also been reported for some derivatives (dppm)) catalyze the hydrogen-transfer reactions from of iron, ruthenium, and osmium.' Most recently, the 2-propanol to ketones and olefins.'V2 Subsequently, we synthesis and X-ray crystal structure of the anion [Irobserved that the hydridoiridium compounds [IrH(q4-di(q1,q3-CBHl10H)(P3O9)I2-,which is an intermediate in the ene)BPh3)2](diene = 1,5COD (1,5-cyclooctadiene), TFB), oxidation of [Ir(P3O9)(q4-1,5-COD)I2with O2to give [Irobtained by addition of potassium hydroxide to 2-propanol (P3OJ (q3-CBH120)]2-,have been described? solutions of [Ir(q4-diene)(PPh3)2]+,also catalyze the hyThe present paper describes the preparation and X-ray drogen-transfer reactions from alcohols to cyclohexanone. and illustrates its structure of [IrH(q1,q3-CBH12)(dppm)] In this case, the presence of the cocatalyst was not necreactivity toward HBF4, CO, and P(OMeI3. essary, suggesting that the potassium hydroxide was needed for the formation of coordinated isopropoxide Results and Discussion groups which can lead to the formation of hydride interSynthesis and Characterization. Treatment of [Irmediates by a 8-elimination reaction. In agreement with (p-OMe)(q4-1,5-COD)]2(1) with dppm in a 1:2 ratio, in this,reactions of [Ir(P-OCHR&4-diene)]2 with PPh3gave methanol, gives a red solution from which the compound [1rH(q4-diene)(PPh3),] and R&0.3 [IrH(q1,q3-CBHlz)(dppm)] (2) is separated as a white solid These results prompted us to study the reactivity of [Ir(P-0CH3)(q4-1,5-COD)I, toward dppp, dpw, and PCy3. (1) Usdn, R.; Oro, L. A.; Sariego, R.; Esteruelas, M.A. J. Organomet. Thus,the complexes [IrH(q4-diene)L2](L2 = dppp, dppe) Chem. 1981,214,399. were obtained in the presence of dppp or dppe,3 while the (2) Udn, R.; Oro, L. A.; Carmona, D.;Eateruelas, M.A.; Focea-Foces, Cano, F. H.; Garcia-Blanco, S. J. Organomet. Chem. 1983,254, 249. reaction with PCy3 leads to [Ir(OMe)(q4-1,5COD)(PCy3)] C.; (3) Femhdez, M.J.; Eeteruelas, M.A.; Covarrubias, M.;Oro, L. A. which is a useful starting material for the synthesis of J. Organomet. Chem. 1986,316,343. u-alkynyl, dihydride silyl, and new alkoxy compound^.^^^ (4) Fernhdez, M. J.; Esteruelas, M. A.; Covarrubias,M.; Oro, L. A.; Apreda, M.C.; Focea-Foces, C.; Cano, F. H. Organometallics 1989, 8, We have now observed that the reaction of [I&1158. OCH3)(q4-1,5-COD)], with dppm leads to an unusual (5) Femindez, M.J.; Esteruelas, M.A.; Covarrubias, M.;Oro, L. A. iridium(II1) compound of formula [IrH(qi,q3-CBH12)- J. Organomet. Chem. 1990,381,275. (6) Bbnnemann, H.; Goddard, R.; Grub, J.; Mynott,R.; Raabe, E.; (dppmll. Wendel, S. Organometallics 1989, 8, 1941. Three years ago, Bhnemann et al.6 described a family (7) a) Cotton, F. A.; Laprade, M.D.; Johnson, B. F. G.; Lewis, J. J. Am. of compounds containng the Co(q1,q3-C8H12)fragment. Chem. Soc. 1971,93,4626. b) Cotton, F. A.; Deeming, A. J.; Josty, P. L.; Ullah, S.S.; Dominaos, A. J. P.; Johnson, B. F. G.; Lewis, J. J. Am. Chem. SOC.1971,93,462< (8) Day, V. W.; Klemperer,W. G.; Lockledge,S. P.; Main,D.J. J. Am. Chem. SOC.1990, 112, 2031.
Universidad de Zaragoza. t Universiat Wtirzburg. f
0276-7333192I2311-3659%03.O0IO
0 1992 American Chemical Society
Esteruelas et al.
3660 Organometallics, Vol. 11, No. 11, 1992
Table I. Selected Bond Distances (A) and Bond Angles (deg) with Estimated Standard Deviations Bond Distances Ir-P1 2.259 (1) P2422 1.821 (6) P2428 1.833 (6) kP2 2.316 (2) I 4 1 2.189 (6) C1-C2 1.52 (1) I d 4 2.115 (6) Cl-CB 1.40 (1) I 4 7 2.256 (7) C2-C3 1.53 (1) Ir-C8 2.147 (6) C344 1.55 (1) Pl-C9 1.867 (6) C445 1.49 (1) P1410 1.822 (6) C546 1.52 (1) Pl-Cl6 1.828 (6) CW7 1.50 (1) P249 1.838 (6) C7-C8 1.45 (1)
Figure 1.
ORTEP diagram
of [IrH(q',q3-C8Hl2)(dppm)].
1
E
1I
I
I..
Pl-Ir-P2 P1-I41 PI-I44 P1-I47 PI-I48 P2-I41 P2-I44 P2-I47 P2-I48 C1-I44 C1-I47 Cl-IrC8 C4-I47 C4-I48 C7-I48 14142
I
Bond Angles 72.55 (6) I4148 177.1 (2) C2-Cl-C8 97.2 (2) Cl-C2-C3 110.1 (2) C2-C3-C4 142.1 (2) I4443 110.2 (2) 144435 C344-425 168.1 (2) C44546 109.5 (2) 96.5 (2) C54647 80.2 (3) 147-C6 68.3 (3) Id748 37.6 (3) C6-C7-C8 79.5 (3) Id841 95.3 (3) 14847 38.3 (5) Cl-CW7 112.7 (5) Pl-Cg-PP
69.5 (4) 127.5 (7) 111.9 (6) 110.7 (6) 109.7 (5) 110.3 (5) 114.7 (6) 110.5 (6) 113.4 (6) 109.3 (5) 66.8 (4) 124.6 (7) 72.8 (4) 74.9 (4) 122.6 (7) 93.9 (3)
with the eight CH2protons of the carbocyclic ligand to the signals group E. The signals B and D which appear as a doublet of triplets (JH-H = 14.7, Jp-H = J p - H = 10.5 Hz (B); JH-H = 14.7, J p - H = J p - H = 8.7 Hz (D)) were assigned to the CH2 protons of the dppm ligand. Table I lista selected bond distances and an les for the structure of 2. The 11424 distance (2.115 (6) ) is in the expected range for an iridium to carbon single bond (sum of covalent radii 2.07 A) and is quite similar to that found for the 1r-C u-bond in the compounds [Ir(q',q2-C8H 3)(PNP)] (PNP = Pr"N(CH2CH2PPh2)2)(2.109 (5) [Ir (q',q2-C6H13)(CO)2(AsPh3)](2.150 (11) A) ,lo and (q4~,~-COD)I~GL-~Z)GL-PP~~)~I~(~',~~-C$I,,)] (2.159 (13) The allylic unit of the carbocyclic ligand is coordinated to the metal in the typical *-allyl manner, which means that the center carbon atom C8 is significantly closer to the metal (Ir-C8, 2.147 (6) A) than the two terminal allyl carbon atoms (Wl,2.189 (6) A; 1&7,2.256 (7) A). The Ir-C(ally1) and C(allyl) 3u(n) 5.9 (3) 0.3795 (7) 0.4989 (9) C17 0.570 (1) no. of params refined 325 7.0 (5) 0.4398 (8) 0.541 (1) C18 0.636 (2) R 0.035 6.6 (4) 0.4544 (8) 0.624 (1) C19 0.643 (2) Rw 0.039 8.1 (5) 0.670 (1) 0.4083 (9) C20 0.578 (2) reflcnfparam ratio 7.46 5.9 (4) 0.3448 (8) 0.6300 (9) C21 0.509 (1) +0.84/4.56 residual electron density, e A-3 0.6444 (8) 3.4 (3) 0.0872 (6) C22 0.268 (1) J ~ -=H 11 Hz, JH-H = 15.6 Hz, 1H, PCHzP), 7.25-8 (m, 20 H, 4.4 (3) 0.1222 (8) 0.6915 (7) C23 0.188 (1) ((C&)ZP)~CH~). 31P(1H)NMR (acetone-d6,20 "C): 6 -60 (br), 0.7693 (9) 5.7 (4) 0.0899 (9) C24 0.176 (1) = 43 Hz). IR (Nujol): v(Ir-H) 2100 (E), 2075 (8) 40.20 (d, Jp-p 0.8014 (9) 6.9 (5) C25 0.241 (2) 0.0264 (9) cm-'; v(BF,-) 1100-1OOO(8) cm-'. Anal. Calcd for BCaFlHdP2: 6.3 (4) -0.0082 (8) 0.7525 (9) C26 0.317 (2) 5.4 (4) C, 51.24; H, 4.69. Found C, 51.48; H, 4.95. 0.6738 (9) 0.0215 (8) C27 0.332 (2) 3.2 (3) 0.4702 (7) 0.0490 (6) Preparation of [ I r ( b , ~ ~ B H 3 ( d p p m ) ( C O(14). ) ] A solution C28 0.266 (1) 4.4 (3) 0.0455 (7) 0.4054 (8) C29 0.335 (1) of [IrH(q1,q3-C8Hlz)(dppm)] in dichloromethane (10 mL) was 5.5 (4) -0.0116 (8) 0.3441 (9) C30 0.311 (2) stirred under CO for 3 h and the resulting solution concentrated 0.346 (1) 6.8 (5) C31 0.217 (2) -0.0640(9) under reduced pressure to 0.5 mL. Addition of hexane caused 6.9 (4) 0.410 (1) -0.0605 (9) C32 0.149 (2) the precipitation of a white solid, which was filtered off, washed 5.8 (4) -0.0037 (8) 0.472 (1) C33 0.173 (1) with hexane, and dried in vacuo. Yield 85 mg (82%). 'H NMR (C&& 20 OC): 6 1.65-2.2 (m, 7 H, -CH-, -CH2-), 2.38 (m, 1H, a Anisotropically refined atoms are given in the form of the iso-CHz-), 2.6-2.9 (m, 2 H, -CHz-), 3.2 (br, 1H, -CHz-), 3.4 (br, tropic equivalent displacement paramekr defined as E, = (4/ 1H, = C H ) , 3.8 (br, 1H, = C H ) , 4.2 (dt, JP-H = J ~ L =H 9.3 Hz, 3)[a2E(l,l)+ b2E(2,2)+ c2B(3,3)+ &(cos y)B(1,2) + ac(cos @)EJH-H = 15 Hz, 1 H, PCHzP), 4.8 (dt, Jp-H = JPLH = 9 Hz, JH-H (1,3) + bc(cos a)B(2,3)]. = 15 Hz, 1 H, PCHzP), 6.80-7.80 (m, 20 H, (C$is)zP)zCHz). 31P(lH)NMR (C&e, 20 "C): 6 -58.9 (d, Jp-p = 5 Hz), -56.5 (d, methanol into a saturated benzene solution of the compound. Jp-p = 5 Hz). "C('HJ NMR (CeDe, 20 "C): 6 13.6 (dd, J p x 2, Crystal data collection parameters are summarized in Table 11. Jpx 68.5 Hz, Cu), 27.16 (dd, J p + = 5, J p x = 10.5 Hz, Intensity data were corrected for Lorentz and polarization effects. CH2CH=) 27.26 (8, -CH&H=), 27.29 (8, -C'Hz-), 35.95 (dd, J p < An empirical absorption correction was applied (*-scan method, = 1,J p c = 26 Hz, -CHCH2-), 37.12 (dd, Jpx = Jp'x = 2 Hz, minimum trRnaminnion 69.7%). The structure was solved by direct -CHCH2-), 46.75 (dd, J p e = 6, J p x = 1.5 Hz, e), 48.48 (dd, methods (SHELXS-86).23 Atomic coordinates (see Table 111) J p + = 1.7, J p c = 8.2, =CH), 52.04 (dd, J p x = 26, J p x = 24.7 and anisotropic thermal parameters of all non-hydrogen atoms HZ,PCHZP), 184.4 (dd, Jpc = 5, J p < 18.6 Hz, CO). IR: v(C0) were refmed by full-matrixleast-squares analysie. The positions (Nujol) 1929 (e), (CHZClz)1935 (a) cm-'. Anal. Calcd for of all hydrogen atoms were calculated according to ideal geometry CSIHmIrOPz: C, 57.21; H, 4.94. Found: C, 57.51; H, 5.31. and refined using the riding method. For the carbon atoms C1, Preparation of [ I r ( r ) 1 , ~ - C ~ H ~ ~ ) ( d ~ ~ m ) ( P ( O M eA) ~ ) l ( 1 5C7, ) . and C8, sp2geometry was assumed, whereas atom C4 and the solution of [IrH(q1,q3-C8Hl2)(dppm)] (100 mg, 0.146 mmol) in other ring carbon atoms were considered to have sp3 geometry. toluene (8mL) was treated with P(OMe)3 (21 pL, 0.175 mmol). All calculations were performed on a Micro-VAXcomputer using The reaction mixture was stirred for 100 min at 75 "C and filtered the program package SDPu from Enraf-Nonius. through Kieaelguhr. The filtrate was concentrated to 0.5 mL, and Acknowledgment. We thank the DGICYT (Project then methanol was added to give a pale yellow solid, which was filtered off, washed with methanol, and dried in vacuo. Yield PB 89-0055, Programa de Promocidn General del Cono92 mg (78%). 'H N M R (C,&, 20 OC): 6 1.9-3.0 (m, 10 H,
