Organometallics 1996, 14, 925-932
925
Successive Reactions of Rhenium Isocyanide Complexes with Nitrogen-ContainingLigands. One-Flask Conversion of ReBr(CO)@NPh) to C(NHPh)(NHR)}l+Br[Re(C0)3(NH2R)2{ Jang-Shyang Fan,+?* Jung-Tzung Lin,tt* Chung-Cheng Chang,* Shou-Jiau Chou,? and Kuang-Lieh Lu*?f Institute of Chemistry, Academia Sinica, Taipei, Taiwan, Republic of China, and Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan, Republic of China Received May 19, 1994@
The isocyanide complexes ReBr(C0)4(CNR) (1)react with Me3NO in CH2Clz to give ReBr(C0)3(CNR)(NMe3)(2). Treatment of 1 with Me3NO in the presence of CH3CN yields the nitrile derivatives ReBr(C0)3(CNR)(NCMe)(3). The latter on reaction with two-electrondonor ligands L (L = CO, PPh3) give ReBr(C0)3(CNR)L. Treatment of 3 with amines in CH2Clz leads to the formation of ReBr(C0)3(CNR)(NH2R)(5). When ReBr(CO)s(CNPh)(NCMe) (3a)is treated with excess amines in CHzClz for a prolonged period, the diaminocarbene complexes ReBr(C0)3(NHzR){C(NHPh)(NHR)} (6) are formed. The latter then react with a further 1equiv of amine to afford [Re(C0)3(NHzR)z{C(NHPh)(NHR)}]+Br(7). A one-flask synthesis of 7 was achieved by the interaction of ReBr(C0)4(CNPh) with Me3NO in the presence of CH3CN followed by reaction with the desired amine in CHzC12 a t ambient temperature. ReBr(C0)3(CNPh)(PPh3)(4a), ReBr(C0)3(NH2W){C(NHPh)(NHPri)} (6a), and [Re(C0)3(NH~Pri)2{ C(NHPh)(NHPr')}]+Br- (7a)have been characterized by X-ray structure determination. 4a crystallizes in the triclinic space group Pi;a = 9.801(4) b = 11.190(5) c = 13.862(5) a = 91.49(3)", p = 108.19(3)",y = 65.52(3)", V = 1305.1(8) A3, 2 = 2, R = 3.1%, and R, = 3.5%. 6a gives monoclinic crystals, space group P211n; a = 9.174(2) b = 19.865(2) c = 12.064(2) /3 = 112.264(2)",V = 2034.6(6) A3, 2 = 4, R = 2.7%, and R, = 3.3%. 7a is monoclinic, space group P21In; a = 13.223(2) b = 10.726(3) c = 20.705(2) ,f3 = 103.35(1)", V = 2857.3(9) A3, 2 = 4, R = 4.8%) and R, = 5.0%.
A, A,
A, A,
A,
A,
A,
A,
A,
Introduction "he chemistry of metal isocyanide complexes has been much less explored than that of the metal carbony1s.l Previously we have found that the diaminocarbene complexes ReBr(CO)4{C(NHPh)(NHR)},prepared from the reaction of ReBr(C0)4(CNPh)with amines, undergo ortho metalation to form the cyclometalated products Re(CO)4{v2-C(NHCsH4)(NHR)}, and the latter proceed with successive Re-C bond formation and cleavage at ambient temperature.2 Considering that "lightly stabilized" complexes with either unsaturated bond character or labile donor ligands have been widely utilized as precursors to incorporate ligands of i n t e r e ~ t ,we ~,~ thought it would be feasible to activate ReBr(C0)4(CNR) to form labile intermediates in order to gain more insight into the chemistry of the rhenium isocyanide complexes. Herein, we describe the isolation of two +Academia Sinica. National Sun Yat-Sen University. Abstract published in Advance ACS Abstracts, January 1, 1995. (1)Elschenbroich, C.; Salzer, A. In Organometallics; VCH: Weinheim, Germany, 1992;p 241. (2)(a)Lu, K. L.; Lee, H. H.; Wang, C. M.; Wen, Y. S. Organometallics 1994, 13, 593. (b) Lu, K. L.; Wang, C. M.; Lee, H. H.; Chen, L. C.; Wen, Y. S. J.Chem. SOC.,Chem. Commun. 1993,706. ( c ) Chen, L. C.; Chem. Chen, M. Y.; Chen, J . H.; Wen, Y. S.; Lu, K. L. J . Organomet. 1992, 425,99. (3)(a)Knox, S.A. R.; Koepke, J. W.; Andrews, M. A.; Kasez, H. D. J . Am. Chem. SOC.1975, 97, 3942. (b) Green, M.; Hughes, A. K.; McGowan, P. C.: Mountford, P.: Scott. P.: Simuson. S. J . J . Chem. Soc.. Dalton Trans. 1992, 1591. ( c ) Green, M.; Mills, 'R. M.; Pain, G. N.; Stone, F. G. A.; Woodward, P. J. Chem. SOC., Dalton Trans. 1982, 1309. (d) Curtis, M.D. Polyhedron 1987, 6, 759.
"lightly stabilized" derivatives, the trimethylamine compounds ReBr(CO)s(CNR)(NMes)as well as the nitrile complexes ReBr(C0)3(CNR)(NCMe). Also we report the one-flask conversion of ReBr(CO)d(CNPh)with nitrogencontaining ligands to form the substituted rhenium diaminocarbene complexes [Re(C0)3(NHzR)z{C(NHPh)(NHR)}l+Br-.
Results and Discussion Preparation of the Complexes ReBr(CO)s(CNR)(NMes)(2) and ReBr(CO)s(CNR)(NCMe)(3). Treatment of the rhenium isocyanide complexes ReBr(C0)r(CNR)(la, R = Ph; lb, R = Pr) in CH2C12 with Me3NO at room temperature gives the trimethylamine-coordinated products ReBr(C0)3(CNR)(NMe3)(2a,R = Ph; 2b, R = Pr) (eq 1).The reactions were monitored with IR
*
@
'
l a , R = Ph lb,R=Pr
2a, R = Ph 2b, R = Pr
spectroscopy by following the diminution of YCO bands of the starting material, ReBr(C0)4(CNR). In general, slightly more than a stoichiometric amount of Me3NO
0276-733319512314-0925$09.00/0 0 1995 American Chemical Society
926 Organometallics, Vol. 14, No. 2, 1995 was required. After the reaction solution was filtered through a small silica gel column followed by evaporation of the solvent, complex 2 was obtained in good purity and in near-quantitative yield, as indicated by its IR and lH NMR spectra. The IR spectrum of 2b showed a characteristic CEN stretching absorption of a terminally coordinated isocyanide at 2202 ~ m - l .The ~ 13CNMR spectrum of 2b showed a triplet centered at 6 144.2 in a 1:l:l ratio with a coupling constant of J(13C14N)= 20 Hz, attributed to the carbon resonance of the CENPr group. This indicates a very symmetric electric charge distribution around the nitrogen atom of the coordinated isocyanide ligand.6s7 The lH NMR spectrum of 2b showed two singlets, a major resonance at 6 2.95 and a much smaller peak at 6 2.85; both were assigned to the methyl protons of a coordinated NMe3 group.s The minor resonance was attributed to a small amount of an isomer. This was supported by the resonances of the propyl groups, which appeared as two sets of absorptions at 6 3.90,1.94, 1.17 and 6 3.73,1.82, 1.09 in a 16:l ratio. The structure of 2 shown in eq 1is believed to be the major isomer, in which the three carbonyls are in a cofacial arrangement as observed in other related c o m p l e ~ e s . ~The J ~ minor isomer might be that in which the trimethylamine group is trans with respect to the isocyanide ligand. In the presence of CH3CN, complex 1 readily reacts with Me3NO to yield the nitrile derivatives ReBr(C0)s(CNR)(NCMe)(3a,R = Ph; 3b,R = Pr) in good yields (eq 2). The infrared spectrum of 3b showed the YCN
-‘ - -‘ Br cO
I/ OC-Re-CNR
I‘ oG oc c I
0
l a , R = Ph ib, R = P r
Me3N0 CH3CN
co
I/
NCMe
OC-Re-CNR
I‘
oG
I
PPh
3
I
oc c
80
3a, R = Ph 3b, R = Pr
4a, R = Ph 4b, R = Pr
absorption at 2211 cm-’, characteristic of a terminally coordinated isocyanide ligand. The lH NMR spectrum of 3 showed that it exists in two isomeric forms in solution. In addition to the appropriate proton absorptions of the isocyanide ligand, two singlets (6 2.44 and 2.42 for 3a,6 2.42 and 2.41 for 3b)were attributed to the methyl group of the acetonitrile ligand of each isomer. The 13C NMR spectrum of 3b showed the carbon resonance of the CNPr group as a triplet (4) (a) Johnson, B. F. G.; Lewis, J.; Pippard, D. A. J. Chem. SOC., Dalton Trans. 1981,407. (b) Johnson, B. F. G.; Lewis, J.; Odiaka, T. I.; Raithby, P. R. J. Organomet. Chem. 1981,216, C56. (c) Deeming, A. J.; Powell, N. I.; Whittaker, C. J. Chem. SOC.,Dalton Trans. 1991, 1875. (d) Dahlinger, IC;Poe, A. J.; Sayal, P. K.; Sekhar, V. C. J.Chem. Soc., Dalton Trans. 1988,2145. (e) Chi, Y.; Wu, C. H. Organometallics 1990,9,2305. (0 Adams, R. D.; Chen, L.; Wu, W. Angew. Chem., Int. Ed. Engl. 1994, 33, 568. (g) Tachikawa, M.; Shapley, J. R. J. Organomet. Chem. 1977,124, C19. (h) Lu, K. L.; Su, C. J.; Lin, Y. W.; Gau, H. M.; Wen, Y. S. Organometallics 1992, 11, 3832. (5)Adams, R. D.; Golembeski, N. M. J . Am. Chem. SOC.1979,101, 2579.
Fan et al.
centered at 6 138.7 in a 1:l:l ratio with a coupling constant of J(13C14N)= 20 Hz. This indicates that there is a very symmetric electric charge distribution around the nitrogen atom of the coordinated isocyanide ligand in 3b.6,7 Complexes containing nitrile4J1J2or trimethylamine8J3 as ligands have been widely used as precursors in organometallic synthesis. They tend to decompose, and only a few trimethylamine derivatives have been isolated and characterized, such as O S ~ ( C O ) ~ ~ ( NIn M~~).~ the present study, the white complexes ReBr(C0)s(CNRI(NMe3) (2)and ReBr(CO)s(CNR)(NCMe)(3)are “lightly stabilized” in CHzClz and decompose slowly, but they could be isolated and are found to be air-stable solids. Reactivity of ReBr(CO)s(CNR)(NCMe) (3). The reactivity of the nitrile complexes ReBr(C0)3(CNR)(NCMe) was primarily examined with two-electrondonor ligands. Bubbling CO gas through a solution of complex 3 in CH2C12 gives ReBr(C0)4(CNR) (1) in almost quantitative yields, as indicated by IR spectroscopy. Addition of PPh3 t o a solution of 3 in CHzC12 affords compounds of the formula ReBr(C0)3(CNR)(PPh3) (4a,R = Ph; 4b, R = Pr) in good yields (eq 2). These reactions showed that the coordinated acetonitrile ligand in 3 is labile and is easily displaced by twoelectron-donor ligands. Complex 4 exists as two isomers in solution. The structure of 4a was confirmed by X-ray crystallography. An ORTEP representation is shown in Figure 1, and pertinent crystallographic details are listed in Tables 1-3. Pseudooctahedral geometry is observed around the Re atom, exemplified by the cis interligand bond angles, which are all within the range 82.4(2)-93.14(3)”. The three CO ligands are arranged in a facial configuration, with a somewhat shorter Re-C distance for CO trans t o the phosphine ligand. The isocyanide ligand is tilted away from the triphenylphosphine group, with the P-Re-C(4) bond angle of 91.6(2)” and the Re-C(4)-N angle of 174.0(7)’ presumably due to steric hindrance. The N-C(4) bond length of 1.14(1) A indicates triple-bond character.14 Reaction of ReBr(CO)dCNR)(NCMe) with Amines. The labile complex 3 on reaction with primary amines readily gives ReBr(C0)3(CNR)(H2NR)(5a,R = Ph, R’ = Pr’; Sb, R = Ph, R = Pr; 5c, R = Ph, R = CH2Ph; 5e, R = Pr, R = Pr’; 5f,R = Pr, R = CH2Ph) (Scheme 1). The interaction of 3 with a secondary amine, HNEt2, leads to the formation of similar derivatives ReBr(CO)3(CNR)(HNEt2)(5d,R = Ph; 5g, R = Pr). (6) Becker, E. D. In High Resolution NMR Theory and Chemical Applications; Academic Press: New York, 1980; p 192. (7) Pretsch, E.; Clerc, T.; Siebl, J.; Simon, W. In Tables of Spectral Data for Structure Determination of Organic Compounds; SpringerVerlag: Berlin, 1989; p C200. (8)Johnson, B. F. G.; Lewis, J.;Raithby, P. R.; Zuccaro, C. J. Chem. SOC.,Chem. Commun. 1979,916. (9) Lu, K. L.; Chen, J. L.; Lin, Y. C.; Peng, S. M. Inorg. Chem. 1988, 27, 1726. (10)(a) Abel, E. W.; Bhatti, M. M.; Hursthouse, M. B.; Malik, K. M. A.; Mazid, M. A. J. Organomet. Chem. 1980, 197, 345. (b) Jones, R. A.; Wilkinson, G.; Gales, A. M. R.; Hursthouse, M. B.; Malik, K. M. A. J. Chem. SOC.,Dalton Trans. 1980, 1771. (11)(a) Burgess, K. Polyhedron 1984,3, 1175. (b) Deeming, A. J . Adv. Organomet. Chem. 1986,26, 1. (12) Lu, K. L.; Liu, L. K.; Su, C. J.; Gau, H. M.; Wang, Y.; Lee, G. H. J. Organomet. Chem., in press. (13)L6we, C.; Shklover, V.; Bosch, H. W.; Berke, H. Chem. Ber. 1993,126, 1769. (14) Allen, F. H.; Kennard, 0.;Watson, D. G.; Brammer, L.; Orpen, A. G.; Taylor, R. J. Chem. SOC.,Perkin Trans. 2 1987, S1.
Re Isocyanide Complexes with N-Containing Ligands
Organometallics, Vol. 14,No. 2, 1995 927 Table 2. Atomic Coordinates and Isotropic Thermal Parameters (A2)for ReBr(CO)3(CNPh)(PPh3)(4a)
C8
c9
c7
atom
P
c35
Figure 1. Molecular structure of ReBr(C0)3(CNPh)(PPh3) (4a).
Table 1. Crystal and Intensity Collection Data for 4a, 6a, and 7a complex fokula fw
4a
6a
7a
C28H20BrN03PRe Cl&~BrN303Re CzoH33BrClzN403Re 715.56 570.48 714.52 pi P21h P2,In 13.223(2) 9.801(4) 9.174(2) 10.726(3) 11.190(5) 19.865(2) 20.705(2) 13.862(5) 12.064(2) 91.49(3) 108.19(3) 112.26(2) 103.35(1) 65.52(3) Y?deg 1305.1(8) v. A3 2034.6(6) 2857.3(9) 1.661 1.821 1.862 Dcdc,g c w 3 4 4 Z L 80.2 59.1 p(Mo Ka),cm-I 63.2 room temp room temp room temp temp radiation Mo Ka Mo Ka Mo Ka 20 (max) 45.0 49.9 49.9 scan type 8-28 0-20 0-20 5242 total no. of fflns 3657 3810 2849 no. of obsd rflns, 2829 2791 F, 2.50(F0) 217 280 no. of obsd 316 variables R 0.047 0.031 0.027 0.035 0.033 0.048 1.320 1.040 0.700 0.001 0.031 0.092 1.86 1.41 1.82
All the compounds synthesized were characterized by IR and NMR spectroscopy. The IR spectra of these complexes showed the same absorption pattern and similar resonance frequencies in the YCO stretching region, compared to spectra for the nitrile complexes ReBr(CO)3(CNR)(NCMe). The 13C NMR spectra of 5e-g also showed the carbon resonance of the CNPr group as a triplet in a 1 : l : l ratio at 6 140.7, 140.6, and 142.3, respectively. This indicates that the nitrogen atoms of the coordinated isocyanide groups possess a symmetric electric charge distribution. Prolonged reaction of ReBr(C0)3(CNPh)(NCMe)(3a)
Bk"Y ~
Re Br
c34
z
Y
X
N O(1) O(2) O(3) C(l) 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(21) C(22) C(23) C(24) C(25) C(26) C(31) C(32) C(33) C(34) C(35) C(36) a
0.22296(4) 0.26505(12) 0.51360(25) 0.2327(9) 0.1884(8) 0.1797(8) -0.1399(8) 0.2044(10) 0.1923(10) -0.0040(12) 0.2362(9) 0.2218(10) 0.0947(10) 0.0795(12) 0.1913(15) 0.3194(13) 0.3354(11) 0.6178(9) 0.7092(13) 0.7810(15) 0.7616(14) 0.6725(12) 0.5991(11) 0.5666(9) 0.6803(10) 0.7220(12) 0.6523(12) 0.5382(12) 0.4948(11) 0.6307(9) 0.7920(10) 0.8820(11) 0.8140(12) 0.6575(12) 0.5627(9)
0.31665(3) 0.35492(10) 0.21942(19) 0.0472(7) 0.5955(6) 0.2484(6) 0.4405(8) 0.4926(9) 0.2707(8) 0.3921(9) 0.1388(8) -0.0604(8) -0.0848(8) -0.1908(10) -0.2686(10) -0.2432(9) -0.1386(9) 0.0526(7) 0.0318(8) -0.0941(11) -0.1982(9) -0.1781(9) -0.0523(9) 0.2085(8) 0.0947(8) 0.0981(10) 0.2148(11) 0.3248(9) 0.3223(8) 0.3047(7) 0.2522(9) 0.3152(10) 0.4326(9) 0.4858(8) 0.4227(8)
0.17412(2) 0.36752(7) 0.20849(15) 0.2568(5) 0.1 154(5) -0.0402(5) 0.1247(5) 0.1378(6) 0.0312(7) 0.1452(6) 0.2254(6) 0.2947(6) 0.2438(6) 0.2801(8) 0.3674(9) 0.4194(7) 0.3820(6) 0.2761(6) 0.3784(7) 0.4313(7) 0.3842(9) 0.2837(9) 0.2293(7) 0.0914(6) 0.0710(6) -0.0149(7) -0.0802(7) -0.0604(6) 0.0236(6) 0.2796(5) 0.2932(6) 0.3428(7) 0.3803(7) 0.3665(7) 0.3165(6)
~
~
~
3.55(2) 5.53(6) 3.57(11) 4.9(4) 6.2(4) 5.8(4) 7.5(5) 4.4(5) 4.2(5) 5.2(6) 4.1(5) 3.9(5) 4.6(5) 6.1(7) 6.4(7) 6.0(7) 5.2(6) 3.9(5) 6.2(7) 8.1(8) 7.5(8) 6.3(7) 5.2(5) 3.9(5) 4.7(5) 5.7(6) 5.9(7) 5.3(6) 4.8(5) 3.7(5) 4.8(5) 5.7(6) 5.5(6) 5.2(6) 4.4(5)
B,,, is the mean of the principal axes of the thermal ellipsoid.
Table 3. Selected Bond Distances and Angles for ReBr(CO)3(CNPh)(PPh3)(4a) Re-Br Re-P Re-C(l) Re-C(2) Re-C(3) Re-C(4) Br-Re-P Br-Re-C( 1) Br-Re-C(2) Br-Re-C(3) Br-Re-C(4) P-Re-C( 1) P-Re-C(2) P-Re-C(3) P-Re-C(4)
(a) Bond Distances (A) 2.6340(13) N-C(4) 2.4772(24) N-C(5) 1.965(9) 0(1)-C(1) 1.996(10) 0(2)-C(2) 1.930(11) 0(3)-C(3) 2.071(9) (b) Bond Angles (deg) 90.61(6) C( l)-Re-C(2) 92.14(23) C(l)-Re-C(3) 174.49(23) C(l)-Re-C(4) 90.3(3) C(2)-Re-C(3) 82.39(21) C(2)-Re-C(4) 90.67(25) C(3)-Re-C(4) 89.47(25) C(4)-N-C(5) 179.1(3) Re-C(4)-N 91.59(23)
1.141(11) 1.383(11) 1.134(11) 0.996( 12) 1.150(12)
93.4(3) 89.3(4) 174.1(3) 89.7(4) 92.1(3) 88.6(3) 177.5(8) 174.0(7)
with excess amines (HzNPr', HzNPr, and HzNCHzPh) in CHzClz at room temperature affords initially the amine-substituted products 5a-c. The latter react continuously with the appropriate amine to yield ReBr(C0)3(H2NR){C(NHPh)(NHR)}(6a,R = Pr'; 6b,R = Pr; 6c,R = CHzPh), in which the coordinated isocyanide ligand has undergone a nucleophilic attack by the amine to give the diaminocarbene (amidinium) group (Scheme 1). The IR spectrum of 6 showed no signal which could be attributed to a terminally coordinated isocyanide ligand. The lH NMR spectrum of 6a exhibited four broad sets ofHN resonances: 6 8.99 and 6.45 (assigned to HNPh and HNPr' of the diaminocarbene ligand) and 6 2.93 and 2.51 (assigned to NHaHb of the coordinated amine group). The line width of the resonances is
_
_
_
_
Fan et al.
928 Organometallics, Vol. 14, No. 2, 1995
Scheme 1 Br
I/
R H N2 NHk
co Me3NO/CH3CN HzNR, CH2Cl2
OC-Re-CNPh
' 0c
I
8
I/
1%'
,NHPh
Table 4. Atomic Coordinates and Isotropic Thermal Parameters (Az)for ReBr(CO)3(NHzPri){C(NHPh)(NHPri)} (6a) atom
oC-Re-c
ocI' c
\NHR
0
la
7
Me3N0 CH3CN CH2C12
3
5
6
X
Y
Z
B,Wa
0.02018(3) -0.07170(9) 0.2187(6) 0.2004(7) 0.2164(7) 0.1394(7) -0.2490(7) -0.2093(6) 0.0956(8) -0.1474(9) -0.1 175(8) 0.3647(11) 0.4535(15) 0.4634(14) 0.163 l(7) 0.1557(8) 0.2982(9) 0.0579( 10) 0.307 l(8) 0.4599(8) 0.5479(9) 0.4873( 10) 0.3390( 11) 0.2453(9)
0.08613( 1) 0.11615(4) 0.0377(3) 0.2195(3) 0.1981(3) 0.03677(25) 0.15720(28) -0.034 19(25) 0.0558(3) 0.13 lO(4) 0.0079(3) 0.0092(6) 0.0574(8) -0.0256(11) 0.1790(3) 0.2138(3) 0.2057(4) 0.2750(4) 0.2563(3) 0.2643(4) 0.3202(4) 0.3667(4) 0.3589(4) 0.3042(4)
0.20823(2) -0.02229(6) 0.1707(5) 0.3370(4) 0.1589(5) 0.4667(4) 0.2491(5) 0.1245(5) 0.369 l(6) 0.2322(6) 0.1568(6) 0.268 1(10) 0.3460(13) 0.2171(15) 0.2448(5) 0.4423(6) 0.5541(6) 0.4458(7) 0.1584(5) 0.2417(6) 0.2367(7) 0.1491(7) 0.0661(7) 0.0705(6)
2.90(1) 4.34(4) 3.6(3) 333) 3.6(3) 5.1(3) 5.8(3) 5.2(3) 333) 4.0(4) 3.7(3) 8.5(6) 11.0(9) 18.9(14) 3.0(3) 3.7(3) 4.7(4) 5.1(4) 3.2(3) 3.9(3) 4.8(4) 4.6(4) 5.4(5) 4.4(4)
Bise is the mean of the principal axes of the thermal ellipsoid.
Table 5. Selected Bond Distances and Angles for ReBr(CO)3(NHzPri){C(NHPh)(NHF'r')} (6a)
eb 02
Re-Br Re-N(1) Re-C(l) Re-C(2) Re-C(3) Re-C(7)
459 c10
Figure 2. Molecular structure of ReBr(CO)3(NHzPri){ C(NHPh)(NHPri)} (6a).
attributed to quadrupolar line broadening by 14N (I = 1). Furthermore, each of the above HN resonances has an associated minor broad peak in a 1:9 ratio at 6 9.27, 7.99, 2.73, and 2.21, respectively, indicating that complex 6a exists as two isomeric forms in solution a t room temperature. On the basis of IR spectroscopy (YCO 2020 (SI, 1919 (SI, 1877 (s) cm-') the major species in solution ~ ~ I3C NMR is assigned to be the fac i ~ 0 m e r . lThe spectrum of 6a showed a downfield peak a t 6 205.2 attributed to the coordinated carbon atom of the diaminocarbene group. In addition to spectroscopic determination, the structure of 6a was also characterized by single-crystal X-ray diffraction analysis. An ORTEP drawing of the molecule is shown in Figure 2. Atomic coordinates are listed in Table 4, and derived bond distances and angles are summarized in Table 5 . The molecule contains a rhenium atom in a distorted-octahedral environment. The structure of 6a is similar to that of the previously reported complex ReBr(C0)3(PPh3){C(NHPh)(NHPri)}.l The three CO groups are arranged in a facial configuration. This is consistent with the IR spectroscopic data, and therefore we suggest that this structure is the major (15)(a) Lukehart, C. M. In Fundamental Transition Metal Organometallic Chemistry; BrooWCole: Monterey, CA, 1985; p 80. (b) Crociani, B.; Boschi, T.; Nicolini, M.; Belluco, U.Znorg. Chem. 1972, 11, 1292.
Br-Re-N( 1) Br-Re-C( 1) Br-Re-C(2) Br-Re-C(3) Br-Re-C(7) N( 1)-Re-C(l) N(l)-Re-C(2) N( 1)-Re-C(3) N(1)-Re-C(7) C( 1)-Re-C(2) N(2)-C(7)-N(3)
(a) Bond Distances (A) 2.6502(9) ~(1)-~(4) 2.252(5) ~(2)-~(7) 1.895(7) N(2)-C(8) 1.891(8) N(3)-C(7) 1.950(7) N(3)-C( 11) 2.209(6) (b) Bond Angles (deg) 81.07(14) C(l)-Re-C(3) 173.61(19) C(l)-Re-C(7) 95.77(20) C(2)-Re-C(3) 86.29(19) C(2)-Re-C(7) 87.16(16) C(3)-Re-C(7) 93.50(24) Re-N(1)-C(4) 176.30(24) C(7)-N(2)-C(8) 94.07(24) C(7)-N(3)-C(ll) 86.14(21) Re-C(7)-N(2) 89.8(3) Re-C(7)-N(3) 115.1(5)
1.5 17(12) 1.309(8) 1.479(8) 1.356(8) 1.426(8)
90.8(3) 95.9(3) 87.6(3) 91.8(3) 173.3(3) 123.1(5) 127.9(5) 127.6(5) 128.8(4) 116.1(4)
isomer in solution. The (371, N(2), and N(3) atoms appear to be sp2 hybridized with a distorted-trigonallanar arrangement. The Re-C(7) distance is 2.209(6) . Both C(7)-N(2) and C(7)-N(3) show partial doublebond character with distances of 1.309(8) and 1.356(8) A, respectively. The dihedral angle of Br-Re-C(7)N(2) is 148.2(4)". In comparison with 5a,b, the complexes 5e,f, which contain the aliphatic isocyanide group CNPr, did not react with amines to form the diaminocarbene products. We attribute this to the electron-releasing properties of the propyl group, which makes the coordinated carbon of the CNPr group more electron rich and consequently makes it inactive toward nucleophilic attack by the amine. These results are consistent with the observations that metal complexes containing an aromatic isocyanide ligand show remarkable differences in reactivity toward nucleophilic reagents compared to their aliphatic analogues.15b Interestingly, continuing the reaction of 3a with excess amine (H2NPr' or HzNPr) for several days at
x
Re Isocyanide Complexes with N-Containing Ligands
Organometallics, Vol. 14, No. 2, 1995 929 Table 6. Atomic Coordinates and Isotropic Thermal Parameters (A21 for [ae(C0)3(NH2Pri)2{C(NHPh)(NHPrl)}l+Br-(7a)
C6
Br
6
CI7
Figure 3. Molecular structure [Re(C0)3(H2NPri)2{ C(NHPh)(NHPri)}]+Br-(7a).
X
Y
z
0.47002(4) 0.70545(12) 0.6156(6) 0.5331(7) 0.5295(8) 0.6582(7) 0.3443(7) 0.27638) 0.3902(8) 0.3931(9) 0.3527(11) 0.4218(10) 0.6183(9) 0.7297( 11) 0.5545( 10) 0.4985(15) 0.5446(25) 0.3981(26) 0.5605(9) 0.4312( 13) 0.3844( 15) 0.4613(15) 0.7288(9) 0.7668( 11) 0.8373( 13) 0.8705( 13) 0.8311(13) 0.7596(11) 0.1306( 19) 0.0140(7) 0.1520(8)
0.47998(5) 0.79914( 14) 0.5141(8) 0.2890(9) 0.6073 11) 0.4908(9) 0.3743(9) 0.4237( 13) 0.7423( 10) 0.4281( 12) 0.4464(14) 0.6437( 14) 0.5153(11) 0.523 1(14) 0.6228( 13) 0.1716( 17) 0.071 l(21) 0.1487(24) 0.5346( 12) 0.6760( 19) 0.6525(27) 0.8135(24) 0.5 170(12) 0.6334( 13) 0.6572( 15) 0.5649( 18) 0.4489( 16) 0.4234(14) 0.7305(49) 0.7554( 14) 0.6281( 13)
0.21512(2) 0.24088(7) 0.18 lO(4) 0.2420(5) 0.3580(4) 0.3366(4) 0.0799(4) 0.2670(6) 0.1765(5) 0.1319(4) 0.2484(7) 0.1923(6) 0.1093(5) 0.1027(6) 0.0742(6) 0.1920(15) 0.2249( 16) 0.2083( 12) 0.3121(6) 0.3494(8) 0.4035(10) 0.3481(10) 0.3998(5) 0.4127(6) 0.473 l(8) 0.5177(7) 0.5027(7) 0.4437(6) 0.09 12(14) 0.0899(3) 0.0447(5)
atom
of
room temperature gives the products ReBr(C0)3(H&R){C(NHPh)(NHR)} (ea, R = Pr’; 6b, R = Pr), which subsequently undergo replacement of bromide with amine, leading to the ionic complexes [Re(C0)3(HaR)2{(NHPh)(NHR)}l+Br-(7a,R = P i ; 7b,R = Pr) (Scheme 1). Utilization of a large excess of amine in the system speeds up these reactions. Complex 7 was purified by chromatography. These ionic products were characterized by IR, NMR, FAB MS, and elemental analysis. Complex 7a was further defined by X-ray crystallography. The FAB MS spectrum of 7a showed the molecular ion at mlz 551. Two broad peaks at 6 9.76 (HNPh) and 6 6.42 (HNPr’) in the lH NMR were assigned to the H N absorptions of the diaminocarbene ligand. The proton resonances of two coordinated isopropylamines were also clearly indicated in the lH NMR spectra. The main feature of these reactions is that the amine replaces the bromide in 6 to form the ionic product 7, without any substitution of the carbonyl groups. This indicates that the carbonyls coordinate at the rhenium center in 6 with a strong n back-bonding facilitated by other surrounding donor ligands. This is corroborated by the relatively lower stretching frequencies of the carbonyl groups (2022, 1919, and 1877 cm-l) and the relatively shorter length of the Re-CO bond (1.895(7), 1.891(8), and 1.950(7) A) in 6a compared to that in ReBr(C0)4{C(NHPh)(NHW)}(YCO 2104,2001, and 1931 cm-l; Re-CO bond 2.00(1), 1.96(1), and 1.90(1) A1.l An ORTEP diagram of [Re(C0)3(H2NPri){ C(NHPh)(NHPri)}l+Br- (7a) is shown in Figure 3. Atomic positional parameters are set out in Table 6, and selected interatomic distances and angles are listed in Table 7. The molecule contains a rhenium atom in a distorted-octahedral environment. This distortion probably arises from the steric requirement of the more bulky coordinated groups such as diaminocarbene and two amine ligands. The three CO groups are arranged in a facial configuration. Two coordinated isopropylamine groups and the diaminocarbene ligands are cis to each other. The bond lengths and bond angles of the diaminocarbene group are similar to those of the related complex ReBr(CO)r{C(NHPh)(NHPr’)}.l The distance of the Re-C(10) bond (2.17(1) A) is within the range of expected values. The counteranion Br- is clearly shown in Figure 3.
&soa
4.66(2) 7.03(7) 4.4(4) 5.2(5) 6.1(6) 4.9(4) 7.8(5) 10.6(8) 8.8(6) 5.8(6) 6.9(8) 6.4(7) 5.0(5) 7.1(8) 6.3(7) 16.8(16) 22.7(23) 16.9(21) 5.0(6) 8.4(10) 14.5(18) 12.9(14) 5.0(6) 7.6(8) 10.2(10) 8.5(9) 8.7( 10) 7.0(8) 30.4(40) 28.8(11) 27.0( 10)
B,,, is the mean of the principal axes of the thermal ellipsoid
Table 7. Selected Bond Distances and Angles for [Re(C0)3(NH2Pr%{C(NHPh)(NHPri))l+Br-(7a) Re-N(1) Re-N(2) Re-C(1) Re-C(2) Re-C(3) Re-C( 10) N( 1)-Re-N(2) N( 1)-Re-C( 1) N(l)-Re-C(2) N( l)-Re-C(3) N(1)-Re-C(10) N(2)-Re-C(1) N( 2) -Re -C(2) N(2)-Re-C(3) N(2)-Re-C(lO) C( l)-Re-C(2) C( l)-Re-C(3)
(a) Bond Distances (A) 2.229(9) ~(1)-~(4) 2.233(10) ~(2)-~(7) 1.872(8) N(3)-C(10) 1.872(16) N(3)-C(ll) 1.890(14) N(4) -C( 10) 2.167( 11) N(4)-C( 14) (b) Bond Angles (deg) 86.0(3) C(l)-Re-C(lO) 94.8(4) C(2)-Re-C(3) 176.5(5) C(2)-Re-C(10) 92.0(5) C(3)-Re-C(10) 85.2(4) Re-N(1)-C(4) 92.8(4) Re-N(2)-C(7) 91.4(5) C(lO)-N(3)-C(ll) 177.8(5) C(lO)-N(4)-C(l4) 85.6(4) Re-C( 10)-N(3) 87.8(6) Re-C(10)-N(4) 88.1(5) N(3)-C(lO)-N(4)
1.492(13) 1.63(3) 1.366(16) 1.467(19) 1.359(14) 1.449(12) 178.4(5) 90.6(6) 92.2(5) 93.6(5) 122.5(6) 121.1(8) 126.9(10) 129.1(10) 127.6(8) 121.8(8) 110.5(9)
One-Flask Conversion of ReBr(CO)r(CNPh)to [Re(CO)s(H2NR)2{C(N)(NHR)}I+Br-. Treatment of ReBr(CO)c(CNPh)with Me3NO in the presence of CH3CN followed by treatment with excess isopropylamine or propylamine in CH2C12 at room temperature for several days results in the formation of the ionic product [Re(C0)3(HzNR)2{C(NHPh)(NHR))]+Br-(7a,b) in a one-flask reaction. This reaction proceeds successively via intermediates 3, 5, and 6 to give the final product 7 in moderate to good yields under very mild reaction conditions (Scheme 1). Complexes 6a,b were obtained as minor byproducts; however, their yields are reduced on prolonging the reaction time. As described above, each intermediate in this reaction sequence could be isolated and characterized.
930 Organometallics, Vol. 14, No. 2, 1995
Conclusion The complexes ReBr(C0)4(CNR) react readily with nitrogen-containing ligands such as Me3N0, CH3CN, and amines. Although the complexes ReBr(C0MCNR)(NCMe) (3) are stable in the solid state, they exhibit high reactivity toward nucleophilic substitution reactions in solution and therefore could be used as useful intermediates for the synthesis of substituted derivatives of ReBr(CO)d(CNR). Furthermore, transformation of the isocyanide complex ReBr(CO)e(CNPh)to the ionic diaminocarbene products [Re(CO)dH2NR)2{C(NHPh)(NHR)}]+Br- was achieved in a one-flask reaction under very mild conditions. The intermediate of each step could be isolated in good to excellent yields.
Experimental Section General Data. The complex ReBr(C0)4(CNR) was prepared previously.' Other reagents were purchased from commercial sources and were used as received. All manipulations were performed with standard Schlenk techniques. Chromatographic separations could be done in air if exposure is limited to a few hours. Solvents were dried by stirring over Ndbenzophenone (diethyl ether) or CaH2 (hexane, CHzC12, CH3CN) and were freshly distilled prior t o use. IR spectra were recorded on a Perkin-Elmer 882 infrared spectrophotometer. NMR spectra were obtained on a Bruker AC-200, an ACP-300, or an AMX-500 FT NMR spectrometer, and mass spectra were recorded on a VG 70-250s mass spectrometer. Elemental analyses were performed using a Perkin-Elmer 2400 CHN elemental analyzer. The 31P chemical shifts are referenced to external 85% H3P04. Synthesis of ReBr(CO)s(CNR)(NMes)(2). All compounds were prepared similarly. A typical preparation is listed here. For ReBr(C0)3(CNPh)(NMes)(2a), a solution of ReBr(COMCNPh) (150 mg, 0.31 mmol) in CHzClz (50 mL) was treated with a solution of Me3NO (28 mg, 0.37 mmol) in CH2Clz (10 mL). The mixture was stirred for 30 min at room temperature, and the IR spectrum showed that the yield is near-quantitative. The solution was filtered through a small silica gel column, and then the solvent was removed under vacuum to give ReBr(CO)s(CNPh)(NMe3)(2a). IR (CHzC12): Y C N 2165 (w)cm-l; YCO 2029 (s), 1957 (s), 1906 (s) cm-l. lH NMR (CDC13): 6 7.45 (m, 5 H, Ph), 3.03, 2.84 (s, 9 H, CH3, two isomers in a 2 5 1 ratio). 13CNMR (CDCl3): 6 192.1, 189.0, 188.3 (CO, major isomer), 185.6, 183.6 (CO, minor isomer), 153.6 (br, CN), 130.4, 129.8, 126.7 (Ph, major isomer), 130.2, 129.6, 126.9 (Ph, minor isomer), 58.75 (CH3). ReBr(C0)3(CNPr)(NMed (2b)was obtained under reaction conditions similar t o those for 2a. IR (CHZClZ): YCN 2202 (w) cm-'; vco 2032 (vs), 1948 (s), 1903 (s) cm-l. lH NMR (CDCl3): 6 3.90, 3.73 (t,2 H, CNCH2, two isomers in a 1:16 ratio), 2.95, 2.85 (s, 9 H, N(CH&, two isomers), 1.94, 1.82 (m, 2 H, CHzCH3, two isomers in a 1:16 ratio), 1.17, 1.09 (t, 3 H, CH3, two isomers in a 1:16 ratio). 13C NMR (CDC13): 6 192.1, 189.5, 188.5 (CO, major isomer), 187.4, 186.5 (CO, minor isomer), 144.2 (CN, 1:l:l ratio, J('3C14N)= 20 Hz), 58.5 (NCHs), 46.1 (CNCHz), 22.7 (CH~CHS), 10.9 (CH3). Synthesis of ReBr(CO)S(CNR)(NCMe)(3). A typical preparation is listed here. For ReBr(C0)3(CNPh)(NCMe)(3a), a solution of R~BI-(CO)~(CNP~) (150 mg, 0.31 mmol) in CHzClz (50 mL) and acetonitrile (1mL) was treated with a solution of Me3NO (28 mg, 0.37 mmol) in CHzCl2 (10 mL). The mixture was stirred for 30 min at room temperature and filtered through a small silica gel column. The solvent was removed under vacuum, and the residue was recrystallized from hexane/CHzClz/CHsCN t o give 3a (136 mg, 0.28 mmol) in 89% yield. Anal. Calcd for CgHloBrN~03Re: C, 29.14; H, 1.63. Found C, 29.43; H, 2.01. IR (CHzClz): VCN 2175 (w) cm-l; YCO 2037 (vs), 1965 (s), 1920 (s) cm-'. lH NMR (CDC13): 6
Fan et al. 7.44 (m, 5 H, Ph), 2.44,2.42 (s,3 H, NCCH3, two isomers). N M R (CDCl3): 6 188.8,188.2,185.4 (CO, major isomer), 185.6, 183.7 (CO, minor isomer), 147.8 (br, CN), 130.2, 129.6, 126.9 (Ph), 120.4 (NCMe, major isomer), 119.8 (NCMe, minor isomer), 3.9 (NCCH3, major isomer), 1.8 (NCCH3, minor isomer). ReBr(C0)3(CNPr)(NCMe) (3b; 146 mg, 0.32 mmol) was obtained under similar reaction conditions in 94% yield based on ReBr(CO)d(CNPr)(150 mg, 0.34 mmol). Anal. Calcd for CsHloBrNzO3Re: C, 23.40; H, 2.17. Found: C, 23.01; H, 2.15. IR (CHZClz): Y C N 2211 (w) cm-l; YCO 2039 (vB),1959 (81, 1915 (s) cm-l. lH NMR (CDC13): 6 3.92, 3.72 (t,2 H, CNCHz, two isomers in a 1:16 ratio), 2.42, 2.41 (s, 3 H, NCCH3, two isomers), 1.83(m, 2 H, CHZCH~), 1.09 (t, 3 H, CH3). 13CNMR (CDC13): 6 189.3,188.4, 185.7 (CO, major isomer), 187.2, 186.3 (CO, minor isomer), 138.7 (CNPr, 1:l:l ratio, J(13C14N)= 20 Hz), 120.2 (NCMe), 46.0 (CNCHz), 22.7 (mZCH3), 3.89 (NCCH3). Carbonylation of 3. Carbon monoxide was bubbled through a solution of 3 in CH2Clz at room temperature. After 1h, the IR spectra indicated that the conversion of 3 to 1 took place in almost quantitative yield. Reaction of ReBr(CO)s(CNR)(NCMe) with Triphenylphosphine. A solution of ReBr(C0)dCNPh) (150 mg, 0.31 mmol) in CHzClz (50 mL) and acetonitrile (1.5 mL) was treated with a solution of Me3NO (28 mg, 0.37 mmol) in CHzClz (5 mL). The mixture was stirred for 20 min at room temperature and filtered through a small silica gel column. The solvent was removed under vacuum to give ReBr(C0)3(CNPh)(NCMe) by following procedures similar to those for the preparation of 3a. The latter was then stirred with triphenylphosphine (84 mg, 0.32 mmol) in CHzCl2 (40 mL) at room temperature for 40 min. After removal of solvent, the residue was chromatographed on a TLC plate with a mixture of CHzClz and hexanes (3:2) as eluent to give ReBr(C0)3(CNPh)(PPh3) (4a; 173 mg, 0.24 mmol) in 77% yield. Anal. Calcd for C2sH20BrN03PRe: C, 46.97; H, 2.81; N, 1.95. Found: C, 46.88; H, 2.34; N, 1.72. IR (CH2Clz): Y C N 2174 (w) cm-'; YCO 2037 (SI, 1965 (m), 1920 (m) cm-'. 'H NMR (CDC13): 6 7.65-7.38 (m, 15 H, Ph). 13C NMR (CDC13): 6 189.6 (d, CO, J c p = 9 Hz), 186.2, 185.1 (CO), 147.8 (br, CN), 133.9, 133.7, 133.1, 132.2, 130.4, 129.8, 129.3, 128.5, 128.3, 126.5 (Ph). 31P NMR (CDC13): 6 3.88, 0.30 (two isomers, l:(trace)). ReBr(C0)3(CNPr)(PPh,) (4b) was obtained under similar reaction conditions in 76% yield based on ReBr(CO)d(CNPr). Anal. Calcd for C26HzzBrN03PRe: C, 44.04; H, 3.25; N, 2.05. Found: C, 43.90; H, 2.99; N, 1.92. IR (CHzClz): YCN 2204 (w) cm-l; YCO 2037 (s), 1964 (m), 1915 (m) cm-l. 'H NMR (CDCl3): 6 7.67-7.38 (m, 15 H, Ph), 3.70 (t, 2 H, CNCHB,minor isomer), 3.35 (t, 2 H, CNCH2, major isomer), 1.81 (m, 2 H, CHzCHz, minor isomer), 1.49 (m, 2 H, CHzCHz, major isomer), 0.97 (t, 3 H, CH2CH3, minor isomer), 0.87 (t, 3 H, CHzCH3, major isomer). I3C NMR (CDCl3): 6 189.9 (d, CO, JCP= 8 Hz), 186.7, 185.5 (CO), 138.4 (CNPr, 1:l:l ratio, J(13C14N)= 19 Hz), 134.0, 133.8, 133.4, 132.5, 130.4, 128.4, 128.2 (Ph), 45.7 (CNCHz), 22.4 (CNCH~CHZ),10.9 (CHzCH3). 31P NMR (CDCl3): 6 4.23 (major isomer), 0.28 (minor isomer). Reaction of ReBr(CO)s(CNPr)(NCMe)with Amines. A typical preparation is listed here. For ReBr(C0)3(CNPr)(NH2Pr') (Se),a solution of ReBr(C0)dCNPr) (150 mg, 0.34 mmol) in CHzCl2 (50 mL) and acetonitrile (1.5 mL) was treated with a solution of Me3NO (28 mg, 0.37 mmol) in CHzClz (5 mL). The mixture was stirred for 20 min at room temperature and filtered through a small silica gel column. The solvent was removed under vacuum to give ReBr(C0)3(CNPr)(NCMe).The latter was stirred with excess isopropylamine (0.15 mL) in CH2Cl2 (40 mL) at room temperature for 30 min. After removal of solvent, the residue was chromatographed on a silica gel TLC plate with a mixture of CHzClz and hexanes (70:30) as eluent to afford ReBr(CO)s(CNPr)(NHzPr')(5e; 103 mg, 0.22 mmol) in 63% yield. Anal. Calcd for C11HlsBrNzOsRe: C, 25.14; H, 3.16; N, 5.87. Found: C, 25.13; H, 3.00; N, 5.61. IR
Re Isocyanide Complexes with N-Containing Ligands (CHzClz): Y C N 2204 (m) cm-'; YCO 2032 (s), 1946 (s), 1904 (s) cm-l. 'H NMR (CDCl3): 6 3.73 (t, 2 H, CNCHz), 3.18 (m, 1H, CH(CHs)z),2.90 (br, 1H, NH,), 2.76 (br, 1H, NHb), 1.82 (m, 2 H, CHZCH~), 1.25 (d, 6 H, CH(CH&), 1.09 (t, 3 H, CHzCHd. 13C NMR (CDC13): 6 190.6, 190.2, 188.4 (CO), 140.7 (l:l:l, CNCHz), 51.5 (CNCH), 46.1 (CNCHz), 24.8, 24.6 (CH(CH3)2), 22.7 (CHZCH~), 11.0 (CHzm3). Complex ReBr(CO)3(CNPr)(NHzCHzPh)(50 was obtained in 46% yield based on ReBr(C0)a (CNPr) under reaction conditions similar t o those for Se, except that the purification was carried out by crystallization with a mixture of CHzClz and hexanes. Anal. Calcd for C14Hl6BrN~03Re:C, 31.68; H, 3.04, N, 5.28. Found: C, 31.79; H, 2.58, N, 5.06. IR (CHzClz): V C N 2204 (m) cm-l; vco 2032 (s), 1947 (s), 1905 ( 8 ) cm-'. lH NMR (CDC13): 6 7.42-7.27 (m, 5 H, Ph), 4.17-3.93 (m, 2 H, CHZPh), 3.70 (t,2 H, CNCHz), 3.18 (br, 2 H, NHz), 1.84 (m, 2 H, CHZCH~), 1.08 (t, 3 H, CHzCH3). 13C NMR (CDCl3): 6 190.4, 190.2, 188.1(CO), 140.6 (l:l:l, CN), 129.3, 128.6,127.7 (Ph), 55.3 (CHZPh),46.1 (CNCHz), 22.7 (CHZCH~), 11.0 (CH3). ReBr(CO)3(CNPr)(NHEtz)(5g) was obtained in 58% yield based on ReBr(CO)d(CNPr)under reaction conditions similar to those for 5e. Anal. Calcd for C11HlsBrNzO3Re: C, 26.80; H, 3.69; N, 5.69. Found: C, 26.60; H, 3.38, N, 5.50. IR (CHZClz): VCN 2203 (w) cm-l; vco 2030 (s), 1946 (81, 1903 (s) cm-l. lH NMR (CDCl3): 6 3.73 (t, 2 H, CNCHz), 3.45-2.91 (m, 4 H, NHCHz), 2.86 (br, 1 H, NH), 1.82 (m, 2 H, CNCHzCHz), 1.16 (m, 6 H, NH(CHzCH3)2), 1.07 (t, 3 H, CNCHzCHzCH3). 13C NMR (CDC13): 6 191.3, 189.9, 188.7 (CO), 142.3 (l:l:l, CNCHz), 49.2, 48.0 (NH(CHzCH3)2), 46.0 (CNCHz), 22.7 (CNCHzCHz), 13.2 (NH(CHzCHz)z),10.9 (CNCHzCHzCH3). Reaction of ReBr(CO)s(CNPh)(NCMe)with N H m for 30 min. A solution of ReBr(C0)4(CNPh)(250 mg, 0.52 mmol) in CHzClz (100 mL) and acetonitrile (2.5 mL) was treated with a solution of Me3NO (43 mg, 0.57 mmol) in CHzClz ( 5 mL). The mixture was stirred for 20 min at room temperature and filtered through a small silica gel column. The solvent was removed under vacuum to give ReBr(C0)3(CNPh)(NCMe).The latter was stirred with excess NH2Pri (0.25 mL) in CHzClz (70 mL) at room temperature for 30 min. The solvent was removed under vacuum, and the residue was chromatographed on a silica gel TLC plate with a mixture of CHZC12 and hexanes (70:30) as eluent t o give ReBr(C0)3(CNPh)(NHzPri)(Sa, 190 mg, 0.37 mmol) in 72% yield. IR (CHZClz): YCN 2167 (m) cm-l; vco 2029 (s), 1954 (s), 1908 (s) cm-l. 'H NMR (CDC13): 6 7.44 (m, 5 H, C&,), 3.23 (m, 1H, CH), 3.01 (br, 2 H, NHd, 1.28 (d, 6 H, CH3). ReBr(C0)3(CNPh)(NHzPr)(5b)was obtained under reaction conditions similar to those for Sa in 68% yield based on ReBr(C0)4(CNPh). IR (CHZClZ): V C N 2166 (m) cm-l; vco 2029 (91, 1954 (s), 1907 (9) cm-l. lH NMR (CDC13): 6 7.44 (m, 5 H, CsH5), 2.97 (m, 2 H, CHz), 1.60 (m, br, 4 H, CHZ and NHd, 0.96 (t, 3 H, CH3). ReBr(C0)3(CNPh)(NHzCHzPh) (5c) was obtained under reaction conditions similar to those for 5a, except that the purification was carried out by crystallization with a mixture of CHzClz and hexanes, in 74% yield based on ReBr(C0h(CNPh). Anal. Calcd for C17H14BrN~03Re:C, 36.15; H, 2.50; N, 4.96. Found: C, 36.47; H, 2.15, N, 4.78. IR (CHzClz): ~ C N 2168 (m) cm-l; vco 2030 (s), 1955 (s), 1910 (s) cm-l. 'H NMR (CDC13): 6 7.44 (s, 5 H, CNC&), 7.37-7.29 (m, 5H, CHzPh), 4.10 (m, 2 H, CHZPh), 3.31 (br, 2 H, NHz). 13CNMR (CDC13): 6 190.2, 189.7, 187.8 (CO), 149.9 (br, CN), 139.1, 130.3, 129.7, 129.3,128.7,127.8,126.9,(CsH5, NHzCHzCdW, 55.5 (NHzCHzC6H5). ReBr(CO)s(CNPh)(NHF&)(5d)was obtained under reaction conditions similar to those for 5a in 64% yield based on ReBr(CO)d(CNPh). Anal. Calcd for C14H16BrN~03Re:C, 31.92; H, 3.06; N, 5.32. Found: C, 31.81; H, 2.90, N, 5.04. IR (CHzClz): V C N 2165 (m) cm-'; vco 2028 (s), 1953 (s), 1908 (s) cm-l. 'H NMR (CDC13): 6 7.44 ( 8 , 5 H, CNCsHs), 3.53-3.03 (m, 1 H, 4 H, NH, NHCHz), 1.21 (m, 6 H, C H d 13CNMR (CDCM: 6 191.2, 189.5, 188.5 (CO), 151.6 (br, with unresolved 1:l:l
Organometallics, Vol. 14, No. 2, 1995 931 pattern, CN), 130.3, 129.7, 126.7 (Ph), 49.6, 48.4 (NH(CH2CH&, 13.5, 13.3 (NH(CHZm3)Z). Formation of ReBr(CO)s(HaNCHSh){C(NHPh)(NHCHz Ph)} (6c). A solution of ReBr(CO)r(CNPh) (150 mg, 0.31 mmol) in CHzClz (50 mL) and acetonitrile (1.5 mL) was treated with a solution of Me3NO (28 mg, 0.37 mmol) in CHzClz ( 5 mL). The mixture was stirred for 20 min at room temperature and filtered through a small silica gel column. The solvent was removed under vacuum to give ReBr(C0)3(CNPh)(NCMe). The latter was stirred with excess NHzCHzPh (0.4 mL) in CHzClz (20 mL) at room temperature for 45 min. After the removal of the solvent under vacuum, the residue was chromatographed on a silica gel TLC plate with CHzClz as eluent t o give a colorless fraction, which was further purified by recrystallization in CHzClz/hexanes t o afford ReBr(C0)3(HzNCHzPh){C(NHPh)(NHCHzPh)} (6c; 129 mg, 0.20 mmol) in 63% yield. Anal. Calcd for C~fi19BrN303Re: C, 43.16; H, 2.87; N, 6.29. Found: C, 43.40; H, 2.94, N, 5.76. IR (CHzClz): vco 2023 (s), 1921 (s), 1879 (s) cm-l. lH NMR (CDC13): 6 9.20, 8.02 (br, s, 1 H, CNHph, two isomers in a 12:l ratio), 7.427.11 (m, 15 H, Ph), 8.27, 6.81 (br, 1 H, CNHCHZPh, two isomers in a 1:12 ratio), 4.92 (m, 2 H, NHCHZPh), 4.10 (m, 1 H, NH&H,HbPh), 3.89 (m, 1H, NHZCHabPh), 3.06 (br, 1H, NMR NHaHbCH2Ph), 2.82 (br, 1 H, NHabCHZPh). (CDCl3): 6 207.6 (Re-C, carbene), 194.6, 193.4 (CO), 139.4, 137.1,136.0,130.5-125.6 (Ph), 55.2 (NHCHz),53.4 (NH2CH2). Mass (FAB): mlz 669 (M+),641 (M+ - CO), 590 (M+ - Br), 483 (M+ - Br - NHZCHzPh), 455 (M+ - CO - Br - NHzCH2Ph), 427 (M+ - 2CO - Br - NHZCHzPh), 399 (M+ - 3CO Br - NHZCHzPh). Reaction of ReBr(CO)s(CNPh)(NCMe)with N H m for 1 Day. A solution of ReBr(CO)r(CNPh) (300 mg, 0.62 mmol) in CHzClz (100 mL) and acetonitrile (2 mL) was treated with a solution of Me3NO (55 mg, 0.75 mmol) in CHzClz (10 mL). The mixture was stirred for 30 min at room temperature and filtered through a small silica gel column. The solvent was removed under vacuum to give ReBr(CO)s(CNPh)(NCMe).The latter was stirred with excess NHzPr' (2 mL) in CHzClz (30 mL) at room temperature for 30 min. The solvent was removed under vacuum, and the residue was chromatographed on a silica gel TLC plate with a mixture of CHzClz and hexanes (80:20)as eluent to give ReBr(C0)3(NHzPr'){C(NHPh)(")) (k, 134 mg, 0.23 mmol) in 38% yield, followed by elution with a mixture of THF and CHzClz (595) to give [Re(C0)3(NHzPr')2{C(NHPh)(NHPri)}]+Br-(7a;110 mg, 0.19 mmol) in 31% yield. For 6a: Anal. Calcd for C16H23BrN303Re: C, 33.60; H, 4.05; N, 7.35. Found: C, 33.75; H, 3.99, N, 7.31. IR (CHzClz): vco 2022 (s), 1919 (s), 1877 (s) cm-'. 'H NMR (CDCl3): 6 9.27, 8.99 (br, s, 1H, NHPh, two isomers in a 1:9 ratio), 7.49-7.08 (m, 5 H, Ph), 7.99. 6.45 (br, d, 1 H, NHCH, two isomers in a 1:9 ratio), 4.58, 3.70 (m, 1 H, NHCH, two isomers in a 9:l ratio), 3.23, 3.01 (m, 1H, NHzCH, two isomers in a 9:l ratio), 2.93, 2.73 (br, 1 H, NHaHb, two isomers in a 9:1 ratio), 2.51, 2.21 (br, 1 H, N H a b , two isomers in a 9:1 ratio), 1.30-1.08 (m, 12 H, CH3). 13CNMR (CDCl3): 6 205.2 (Re-C, carbene), 194.7, 193.7 (2:1, CO), 136.3, 130.5, 127.7, 125.3 (Ph), 56.0, 51.3 (CH), 25.2, 24.6, 24.0, 23.9 (CH3). For 7a: Anal. Calcd for C19H32BrN403Re: C, 36.18; H, 5.08; N, 8.99. Found: C, 35.33; H, 4.19, N, 8.38. IR (CHzClz): 6co 2020 (SI, 1913 (SI, 1894 (s) cm-l. lH NMR (CDC13): 6 9.76 (br, s, 1 H, NHPh), 7.48-7.20 (m, 5 H, Ph), 6.42 (br, d, 1 H, NHCH), 4.72 (br, 2 H, NHz), 4.60 (m, 1H, NHzCH), 3.44 (br, 2 H, NHd, 3.25 (m, 1 H, NHzCH), 1.40 (d, 6 H, CH3), 1.35 (d, 6 H, CH3), 1.24 (d, 6 H, CH3). Mass (FAB, Re187):mlz 551 (M+),492 (M' - NHzPri), 464 (M+ - NH2Pri - CO), 433 (M+ - 2NHzPri), 405 (M' - 2NHzPr' - CO). Reaction of ReBr(CO)&NPh)(NCMe) with NH- for 2 Days. A solution of ReBr(CO)a(CNPh)(NCMe)(232 mg, 0.47 mmol) in CHzClz (125 mL) was treated with excess NHzPr (4 mL) and stirred at room temperature for 2 days. The solvent was removed under vacuum, and the residue was chromatographed on a silica gel TLC plate with a mixture of CHzClz
Fan et a1.
932 Organometallics, Vol. 14, No. 2, 1995
After the mixture was stirred for 30 min at room temperature, and hexanes (80:20) as eluent to give ReBr(C0)dNHzPr)excess NHzPr (3 mL) was added and this solution was stirred {C(NHPh)(NHPr)} (6b; 49 mg, 0.09 mmol) in 18% yield, at room temperature for 3 days. The solvent was removed followed by elution with a mixture of THF and CHzClz (50:50) under vacuum, and the residue was chromatographed on a (7b;72 mg, to give [Re(CO)3(NHzPr)z{C(NHPh)(NHPr)}l+Brsilica gel TLC plate with a mixture of CHzClz and hexanes 0.11 mmol) in 24% yield. For 6b: IR (CHzClz): YCO 2020 (s), (80:20) as eluent to give ReBr(CO)3(NHzPr){C(NHPh)(NHPr)} 1915 (s), 1878 (s) cm-l. lH NMR (CDC13): 6 9.32, 9.03 (br, s, (6b; 3 mg, 0.005 mmol) in 2% yield, followed by elution with 1 H, NHPh, two isomers in a 1:7 ratio), 7.48-7.10 (m, 5 H, a mixture of THF and CHzClz (80:20) t o give [Re(C0)3(NHzPh), 7.92, 6.61 (br, 1 H, NHCHz, two isomers in a 1:7 ratio), Pr)z{C(NHPh)(NHPr)}]+Br(7b; 125 mg, 0.20 mmol) in 77% 3.65 (m, 2 H, NHCHz), 2.97 (m, 2 H, NHzCHz), 2.87 (br, 1 H, yield. NH&,), 2.63,2.41 (br, 1H, NH&,, two isomers in a 7:l ratio), Crystallographic Structure Determination. Crystals 1.56 (m, 4 H, CHZCH~), 0.91 (m, 6 H, CH3). For 7b: Anal. of ReBdC0)3(CNPhXPPb) (4a),ReBr(CO)3(NHzW){C(NHPh)Calcd for ReBrClgH3zN403: C, 36.18; H, 5.08; N, 8.99. (NHPr')}(6a),and [R~(CO)~(HZNP~')Z{C(NHP~)(NHP~~)}]+B~ Found: C, 36.15; H, 5.55, N, 8.44. IR (CHzClz): YCO 2020 (s), (7a) were grown from CHzClhexane solutions at -5 "C. 1912 (s), 1887 (s) cm-l. lH NMR (CDC13): S 10.03 (br, s, 1H, Specimens of suitable quality were mounted on a glass NHPh), 7.46-7.18 (m, 5 H, Ph), 6.57 (br, t, 1H, NHCHz), 4.63 capillary and used for measurement of precise cell constants (br, 2 H, NHz), 3.78 (br, 2 H, N H z ) , 3.64 (m, 2 H, CHz), 2.90 and intensity data collection. Diffraction measurements were (m, 4 H, CHz), 1.69 (m, 4 H, CHZCH~), 1.54 (m, 2 H, CHZCH~), made on an Enraf-Nonius CAD-4 s a c t o m e t e r using graphite0.94 (t, 6 H, CH3), 0.89 (t, 3 H, CH3). Mass (FAB, Rela'): mlz = I0.709 30 A) with the monochromatized Mo Ka radiation (, 551 (M+),492 (M+ - NHZPr), 464 (M+ - NHzPr - CO), 433 8-28 scan mode. Unit cells were determined and refined (M+ - 2NHzPr), 405 (M+ - 2NHzPr - CO). One-Flask Synthesis of [Re(CO)s(NH2Pr')a{C(NHPh)- using 25 randomly selected reflections obtained with the automatic search, center, index, and least-squares routines. (NHPr')}]+Br-(7a) for 2 Days. A solution of ReBr(C0)rAnomalous dispersion corrections were applied to all non(CNPh) (155 mg, 0.32 mmol) in CHzClz (40 mL) and acetonihydrogen atoms. Lorentdpolarization (L,) and empirical trile (0.1 mL) was treated with a solution of Me3NO (25 mg, absorption corrections based on three azimuthal scans were 0.33 mmol) in CHzClz (10 mL) and acetonitrile (0.05 mL). applied t o the data for each structure. Space groups were After the mixture was stirred for 30 min at room temperature, determined from the systematic absences observed during data excess NHzPr' (3 mL) was added and this solution was stirred collection. The centrosymmetric space group was initially at room temperature for 2 days. The solvent was removed assumed and later confirmed by the results of refinement for under vacuum, and the residue was chromatographed on a 4a. The systematic absences in the diffraction data for 6a and silica gel TLC plate with a mixture of CHzClz and hexanes 7a unambiguously established the space group as P 2 h The (80:20) as eluent to give R~B~(CO)~(NHZP~.I)(C(NHP~)(")) (6a;48 mg, 0.08 mmol) in 26% yield, followed by elution with structures were solved by the Patterson method. All remaining non-hydrogen atoms were located from the difference a mixture of THF and CHzClz (50:50) to give [Re(C0)3(NHzFourier map, and they were included in the final refinement Pri)z{C(NHPh)(NHPri)}]+Br(7a; 51 mg, 0.08 mmol) in 25% cycle and refined by full-matrix least squares. A CHzClz yield. solvent molecule packs in the lattice along with a molecule of One-Flask Synthesis of [R~(CO)S(N~P~')~{C(NHP~)(NHPri)}]+Br- (7a) for 4 Days. A solution of ReBr(C0)r7a, but there are no interactions between them. All the data processing was carried out on a Microvax 3600 using the (CNPh) (59 mg, 0.12 mmol) in CHzClz (15 mL) and acetonitrile NRCC SDP program.16 (0.03 mL) was treated with a solution of Me3NO (9 mg, 0.12 mmol) in CHzClz (10 mL) and acetonitrile (0.03 mL). After the mixture was stirred for 30 min at room temperature, excess Acknowledgment. We thank the National Science NHzW (3 mL) was added and this solution was stirred at room Council of the Republic of China for financial support. temperature for 4 days. The solvent was removed under vacuum, and the residue was chromatographed on a silica gel Supplementary Material Available: Tables of atomic TLC plate with a mixture of CHzClz and hexanes (80:20) as coordinates, crystal and intensity collection data, anisotropic (6a; 12 eluent t o give ReBr(C0)3(NHzPri){C(NHPh)(NHPri)} thermal parameters, and bond lengths and angles for 4a, 6a, mg, 0.02 mmol) in 18% yield, followed by elution with a and 7a (17 pages). Ordering information is given on any mixture of THF and CHzClz (80:20) to give [Re(C0)3(NHzPr')zcurrent masthead page. {C(NHPh)(NHPri)}]+Br-(7a;35 mg, 0.56 mmol) in 46% yield. OM9403855 One-Flask Synthesis of [Re(CO)s(NH2Pr)2{C(Nh)(NHPr)}]+Br- (7b) for 3 Days. A solution of ReBr(C0)4(16)Gabe, E. J.; Lee, F. L.; Le Page, Y. In Crystallographic (CNPh) (124 mg, 0.26 mmol) in CHzClz (25 mL) and acetoniComputing 3; Data Collection, Structure Determination, Proteins, and trile (0.03 mL) was treated with a solution of Me3NO (20 mg, Databases; Sheldrick, G. M., Kriiger, C., Goddard, R., Eds.; Clarendon Press: Oxford, England, 1985; pp 167-174. 0.26 mmol) in CHzClz (10 mL) and acetonitrile (0.03 mL). ~
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