Organometallics 1995, 14, 3370-3376
3370
A Novel Synthetic Route to Molybdenum Hydrido-Thiocarbamoyl and Hydrosulfido-Carkiyne Complexes by Reactions of truns=Mo(N2)2(R2PC2~1PR2)2 with NJV-Dimethylthioformamide Xiao-Liang Luo,* Gregory J. Kubas,* Carol J. Burns, and Ray J. Buixher Materials and Chemical Design Group (CST-lo), Mail Stop C346, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 Received February 27, 1995@ The reactions of bis(dinitr0gen)molybdenum complexes trans-Mo(Nz)2(R2PC2€14PRz)2 (R = Ph, Et) with Nfl-dimethylthioformamide(HC(S)NMe2)in refluxing benzene under argon give the molybdenum hydrido-thiocarbamoyl complexes MOH(~~~-C(S)NM~~)(R~PC~H~PR~)~ (R = Ph (la),E t (lb)). On heating a t 125 "C in toluene solutions, compounds :la and l b rearrange to form the molybdenum hydrosulfido-aminocarbyne complexes truns-Mo(SH)( " C N M ~ Z ) ( R Z P C ~ H ~(R P R=~Ph ) ~ (2a),E t (2b)). A mechanism is proposed for t h w thermal rearrangement which involves migration of the hydride ligand from molybdenum t o the sulfur atom of the thiocarbamoyl ligand to give the 16-electron Fischer carbene intermediate Mo(=C( S H ) N M ~ ~ ) ( R ~ P C ~ H ~ followed P R Z ) ~by , migration of the hydrosulfido group from the carbene carbon to molybdenum. The molecular structures of compounds la anid 2a have been determined by single-crystal X-ray diffraction studies. Crystallographic d a t a for la: monoclinic, space oup C2/c, u = 19.536(4) b = 15.950(3) c = 15.793(3) fl = 105.54(3)", V = 4741(2) 3, 2 = 4, and R = 0.037. Crystallographic data for 2a: monoclilnic, space group P21/c, a = 19.516(4)A, b = 12.301(2) A, c = 19.899(4) p = 102.46(3)", V := 4665 (2) A3, 2 = 4, and R = 0.062.
f
A,
A, A,
A,
variety of small molecule^.^-^ In pstrticular, the reaction of M o ( C O ) ( R ~ P C ~ H ~ with P R ~ )Hzl ~ gives a dihydrogen The reactivity of bis(dinitr0gen)molybdenum comwhen R is an complex Mo(r2-Hz)(CO)(RzPC2H41?'R2)2 has been plexes of the type tran~-Mo(Na)z(R2PC2H4PR2)2 electron-withdrawing phenyl or tjenzyl group or a diextensively studied.l Hidai and co-workers reported hydride complex MoH2(CO)(R2PC2€I4PR2)2when R is an that the decarbonylation of NJV-dimethylformamide electron-donating alkyl Thus,electronic control gives trans(DMF) by tran~-Mo(N2)2(Ph2PC2H4PPh2)2 of v2-dihydrogenversus dihydride cmordination has been Mo(DMF)(CO)(Ph2PCzI&PPh2)2,which is converted into achieved in this molybdenum sys hem. trans-Mo(Nz)(COXPh2PC2HPPh2)2under dinitrogen and We were interested in synthesizing the formally 16then into Mo(CO)(Ph2PCzH4PPh2)2under argon.2 electron thiocarbonyl complexes of type Mo(CSXR2Recently, we reported the one-step synthesis of a PCzH4PRz)z with a wide range of steric and electronic series of formally 16-electron complexes of the type Moproperties and using these complexes for the binding (CO)(R2PC2H4PR2)2by the reactions of bis(dinitrogen)and activation of small molecules. In an attempt to molybdenum complexes ~ ~ u ~ s - M o ( N ~ ) ~ ( R ~ Pprepare C ~ H ~MO(CS)(R~PC~&PR~)~ PR~)~ by the reactions of transwith an ester such as ethyl acetate in refluxing benzene Mo(N~)~(R~PC~H with ~ P N,N-dimethylthioformaR~)~ Some of the Mo(CO)(R2PC2&or toluene under mide (HC(S)NMe2)using a procedure similar to that PR2)2 complexes, i.e., for R = Ph,2bB u ~C, ~ H Z P ~ ,and ~" we used for the synthesis of MO(CO)(:E'~~PC~H~PP~~)~,~ C H ~ C ~ H P ~ - have M ~ , been ~ * shown by X-ray crystalhave unexpectedly found a novel synthetic route to lography or variable-temperature lH NMR spectroscopy molybdenum hydrido- thiocarbamoyl and hydrosulfidoto adopt an octahedral structure, in which an agostic aminocarbyne complexes. Herein we report the synMo. .H-C interaction occupies an otherwise vacant thesis and spectroscopic and crystallographic characcoordination site trans to the CO ligand. terization of these complexes. The weak agostic Mo**-H-C interaction in Mo(C0)(RzPCzH4PR212 can be readily displaced by a wide Results and Discussion
Introduction
Abstract published in Advance ACS Abstracts, June 1, 1995. (1)( a )Hidai, M.; Mizobe, Y. In Reactions of Coordinated Ligands; Braterman, P. S., Ed.; Plenum Press: New York, 1989: Vol. 2, p 53. (b) Georger, T. A. In Homogeneous Catalysis with Metal Phosphine Complexes; Pignolet, L. H., Ed.: Plenum Press: New York, 1983; p 405. ( 2 ) ( a )Tatsumi, T.; Tominaga, H.; Hidai, M.; Uchida, Y. J . Organomet. Chem. 1976, 114, C27. tb) Sato, M.; Tatsumi, T.; Kodama, T.; Hidai, M.; Uchida, T.; Uchida, Y. J . Am. Chem. SOC.1978, 100, 4447. ( 3 )( a )Luo, X.-L.; Kubas, G. J.;Burns, C. J.: Eckert, J. Inorg. Chem. 1994,33,5219. cbJ Kubas, G. J.: Bums, C. J.; Eckert, J.; Johnson, S. W.: Larson, A. C.; Vergamini, P. J.; Unkefer, C. J.; Khalsa, G. R. K.: Jackson, S. A.; Eisenstein, 0. J . A m . Chem. SOC.1993, 115, 569. ( 4 ) Luo, X.-L.; Kubas, G. J.; Burns, C. J.; Bryan, J . C.: Butcher, R. J. Inorg. Chem., submitted for publication.
Synthesis and Spectroscopic Characterization of Molybdenum Hydrido-Thiocarbamoyl Complexes MoH(tl2-C(S)NMe2)(R2IPC2H4PR2)2(R = Ph (la),Et (lb)). Most complexes containing the thiocarbamoyl ligand C(SINMe2 have been prepared either by diplacement of C1- from ClC(S)NMe2by metal carbonyl ( 5 )( a )Luo, X.-L.; Kubas, G. J.; Bryan. J. C.; Burns, C. J.; Unkefer, C. J. J . Am. Chem. SOC.1994, 116, 1031'2L rb) Luo, X.-L.; Kubas, G. J.: Burns, C. J.:Bryan. J. C.: Unkefer, C. J. J. Am. Chem. SOC.1995,117, 1159.
0276-7333/95/2314-3370$09.0QIQ 0 1995 American Chemical Society
Novel Synthetic Route to Mo Complexes anions6 or by oxidative addition of the C-X bonds of XC(S)NMe2 (X = Cl,7 SMe,8 S Z C N M ~N(Ph)(C(S)~,~ NMe& to metal complexes. We have now found a convenient synthetic route to molybdenum thiocarbamoyl complexes, which involves the oxidative cleavage of the aldehydic C-H bond in HC(SINMe2 by biddinitrogenlmolybdenum complexes of the type trans-Mo(N2)2(&PC2H4PR2)2. Thus, the reactions of truns-Mo(Nz)z(RzPCzH4PRz)z (R = Ph, Et) with HC(SNMe2 in refluxing benzene under argon gave deep red solutions, from which the hydrido-thiocarbamoyl complexes MoH(q2C(S)NMe2)(R2PC2H4PR2)2(R = Ph (la),Et (lb))were isolated as red-brown solids in high yields and high purity (eq 1).
Organometallics, Vol. 14,No. 7, 1995 3371
&-4h )
.
,
I
I
eo
.
,
,...
.
75
70
PPM
188 K
, , , ,
, , , ,
65
60
Figure 1. Variable-temperature 31P{1H}NMR spectra (80.96MHz) of MOH(~;~~-C(S)NM~Z)(P~~PC~H~PP~Z (la)in C&CD3.
343 K 298 K
R = Ph (la), Et (lb)
188 K
To our knowledge, only one hydrido- thiocarbamoyl 65 60 SO PPU complex, i.e., [IrH(q2-C(S)NMe2)(CO)(PPh3)21+, has been reported,7c but the compound was not characterized Figure 2. Variable-temperature 31P{ lH) NMR spectra (80.96MHz) of MOH(~;~~-C(S)NM~~)(E~ZPC~H~PE~ (lb)in crystallographically. The tungsten hydrido-carbamoyl CtjD5CD3. complex WH(q2-C(0)NMe2)(Ph2PC2H4PPh2)2, which is analogous t o compounds la and lb, has recently been prepared from the reaction of trun~-W(Nz)z(Ph2PC2H4- resonances at 6 81.3 and 61.4 show a very large 2 J p p coupling constant of 148 Hz, which suggests a trans PPhz)2 with Nfl-dimethyl formamide. disposition of two inequivalent phosphorus atoms. The The 'H NMR spectrum of l a in C6D&D3 at 298 K displays a binomial quintet resonance at 6 -3.63 ( 2 J ~ 'H ~ and 31P{'H} NMR spectroscopic data are consistent with a seven-coordinate pentagonal bipyramidal struc= 39.5 Hz) assignable to the hydride ligand, two singlet ture with two phosphorus atoms occupying the two resonances a t 6 2.69 and 2.34 due to the two inequivatrans axial sites as shown in eq 1. lent N-methyl groups, and resonances due to the diphosphine ligands. The observation of a quintet The variable-temperature 'H and 31P{'H} NMR spechydride resonance indicates that the four phosphorus tra of l b in C&CD3 are quite similar to those of la. atoms are equivalent a t this temperature due to rapid The hydride region of the 'H NMR spectrum at 298 K fluxionality that is commonly observed for sevendisplays a quintet resonance a t 6 -6.44 ( 2 J ~ = p 36.7 coordinate complexes.'0 When the sample is cooled, the Hz), which collapses at 188 K into a doublet ( 2 J ~ = p 93 hydride resonance broadens and then collapses at 188 Hz) of multiplets. The variable-temperature 31P{'H} K into a broad doublet ( 2 J ~ = p 85 Hz). The variableNMR spectra of l b are shown in Figure 2. At 298 K, temperature 31P{'H} N M R spectra of l a in CsD5CD3 are two broad resonances at 6 63.5 and 53.0 are observed shown in Figure 1. At 298 K, a single resonance at 6 which coalesce into a broad peak at 343 K. When the 74.5 is observed. When the sample is cooled to 188 K, sample is cooled to 188 K, four resonances with equal this resonance collapses into four resonances with equal intensity are observed at 6 65.9, 61.4, 51.6, and 49.0. intensity at 6 81.3,77.2,63.5,and 61.4. The two doublet The two resonances at 6 61.4 and 49.0 show a very large trans 2 J p p coupling constant of 145 Hz. On the basis of ( 6 )( a )Dean, W.K.; Treichel, P. M. J . Organomet. Chem. 1974,66, the lH and 31P{'H} NMR spectroscopic data, compound 87. ( b ) Dean, W. K. J . Organomet. Chem. 1977,135, 195. ( 7 )( a )Green, C. R.; Angelici, R. J. Inorg. Chem. 1972, 11, 2095. rb) l b is isostructural with la and adopts the pentagonal Dean, W. K.; Charles, R. S.;VanDerveer, D. G. Inorg. Chem. 1977, bipyramidal structure shown in eq 1. 16, 3328. (c) Gal, A. W.; Ambrosius, H. P. M. M.; Ver Der Ploeg, A. F. M. J.; Bosman, W. P. J. Organomet. Chem. 1978, 149, 81. ( d )Gal, W. The IR spectra of l a and l b in Nujol mulls show K. J . Organomet. Chem. 1980, 190, 353. ( e ) Corain, B.; Martelli, M. broad bands at 1886 and 1889 cm-l, respectively, which Inorg. Nucl. Chem. Lett. 1972, 8, 39. (D Gibson, J. A. E.;Cowie, M. are assigned to 4Mo-HI. The 4C-N) bands for the Organometallics 1984, 3, 722. (8)Gal, A. W.; Ver Der Ploeg, A. F. M. J.; Vollenbroek, F. A.; thiocarbamoyl ligand appear at 1521 and 1524 cm-', Bosman, W. P. J . Organomet. Chem. 1975, 96, 123. respectively, for l a and lb. Both stretching frequencies ( 9 )( a )Ishida, T.; Mizobe, Y.; Tanase, T.; Hidai, M. J. Organomet. Chem. 1991,409, 355. ( b )Ishida, T.; Mizobe, Y.; Tanase, T.; Hidai, M. are outside the range of 1575-1650 cm-' typically found Chem. Lett. 1988, 441. for an q2-bound C(S)NMe2 g r ~ u p . ~Nevertheless, -~ a (10)Luo, X.-L.; Schulte, G. K.; Demou, P.; Crabtree, R. H. Inorg. similarly low C-N stretching frequency of 1526 cm-l Chem. 1990,29, 4268 and references therein.
Luo et al.
3372 Organometallics, Vol. 14, No. 7, 1995
Table 1. Crytallographic Data for
MoH(112-C(S)MMez)(PhzPCzH4PPhz)z (la) empirical formula fw cryst syst space group a,A b, A C,
A
P, deg
v, A3
z
p(calcd), g cm-3 y(Mo Ka),cm-' minimax transmissn coeff
T,K Ra RWb a
R
=
CjjH5jMoNPJ3 981.88 monoclinic c2tc 19.536(41 15.950(3) 15.793(3) 105.54(3) 4741(2) 4 1.376 4.94 0.72-0.79 203 0.037 0.055
Cilld
-
RW= [ X ~ ( l F o l lFcl)2E~F,,'l"2. EllFol - lFcllE~Fol.
Cll3i Table 2. Selected Bond Lengths Cdi) and Angles (deg)for MOH(~~~-C(S)NM~Z)(P~ZPC~H~PP~~)Z (la)
Mo-P(l) Mo-P(2 ) Mo-C Mo-H C-N N-C(lb) P( 1)-Mo-P(la) P(l)-Mo-P(2) P(l)-Mo-P(2a) P(11-Mo-C P(2 I- Mo-C P(l)-Mo-S S-Mo-P(la) S-Mo-C Mo-C-S S-C-N C-N-C(lb1 P(l)-Mo-H P( la)-Mo-H C-Mo-H
Bond Lengths Mo-P(2) 2.435( 1) 2.477( 1) Mo-P(2a) 2.049(3) Mo-S 1.56(5) c-s N-C(la) 1.310(5) 1.439(7) Bond Angles 177.4(1j P(2l-Mo-P( l a ) 102.3(11 P(la)-Mo-P(ZaJ 79.6(11 P(2)-Mo-P(2a) 88.7(1) C-Mo-P(la) 136.5(1) C-Mo-P(Za) 82.5(1) P(2)-Mo-S 95.6(1) S-Mo-P(2a) 41.9 (1) Mo-S-C 86.9(1) Mo-C-N 121.7(21 C-N-C(laj 119.8(3) C(la)-N-C(lb) 100.4(20) P(2)-Mo-H 78.7(20) P(2a)-Mo-H 69.9(20) S-Mo-H
2.477(11 2.477( 1I 2.626( 1j 1.755(1) 1.438(5)
79.6(1) 102.3(11 87.0(11 88.7(1) 136.5(1) 97.4(1) 162x1 51.2(1) 151.4(21 125.513) 114.7(3) 145.0(20) 71.3(20) 111.8(20)
has been reported for W(v2-C(S)NEt&S2CNEt2)(CO)(PhCHS).ll In the majority of mononuclear thiocarbamoyl complexes reported to date, the thiocarbamoyl ligand adopts the v2 coordination mode.6-8 The v1 coordination mode has been reported only for square-planar d8 specie^,'^.^,^ but no examples have been characterized by X-ray crystallography. The v1 coordination of the C(SINMe2 group in l a and lb is unlikely since it would give less stable 16-electron octahedral complexes. X-ray Crystal Structure of MoH(q2-C(S)NMe& (Ph2PC&PPh2)2 (la). In order to obtain more detailed information on the mode of coordination of the C(SINMe2 group in compounds l a and lb, an X-ray crystallographic study has been performed on a single crystal of la. A summary of the crystallographic data is given in Table 1, and the selected bond lengths and angles are given in Table 2 1. An ORTEP drawing is shown in Figure 3. Compound l a is the first crystallographically characterized hydrido-thiocarbamoyl complex. Consistent with the solution lH and 31P{1H)NMR spectroscopic data (uide supra), the coordination geometry around the molybdenum atom in l a is best described as a distorted pentagonal bipyramid. The two (11)Mayr, A.;McDermott, G. A.; Dorries, A. M.; Holder, A. K. J . Am. Chem. SOC.1986,108,310.
Cilbl Cilal
Figure 3. ORTEP drawing of MoH(q2-C(S)NMez)(PhzPCzH4PPhdz (la). trans axial sites are occupied by the two phosphorus atoms P(1)and P(la), whereas the five equatorial sites are occupied by the hydride ligand, the y2-thiocarbamoyl ligand, and the two phosphorus atoms P(2) and P(2a). The molybdenum atom essentially lies on the leastsquares plane defined by the atoms at the five e uatorial sites, with an insignificant deviation of 0.002 from the plane. The position of the hydride ligand was determined in the difference Fourier map, and it behaved well on refinement. The hydride ligand occupies the equatorial site between the P(2a) and the C atom of the thiocarbamoyl ligand. The Mo-H distance of 1.56(5)A is somewhat shorter than the value of 1.685(3)A found for (y5-CsH&MoH2 by a neutron diffraction study.12 This is not surprising in view of the tendency of X-ray crystallography to give foreshortened metalhydrogen distances.13 The MoCSNMe2 unit in l a is virtually planar. Thus, the largest deviation from the least-squares plane defined by the atoms Mo, C, S, N, C(la), and C(lb) is only 0.015 A for S and C(1b). The five torsional angles, Mo-S-C-N, Mo-C-N-C(la), Mo-C-N-C(lb), S-CN-C(la), and S-C-N-C(lb), are -179.6", 180.0", -1.O", -0.9", and 178.1", respectively, confirming the near planarity of the MoCSNMe2 moiety. The C-N distance in l a is 1.310(5) A, which is significantly shorter than the N-C(la) and N-C(lb) distances of 1.438(5) and 1.439(7)A, respectively, and is very similar to the C-N distances found in aminocarbene complexes14 and typical organic amides.15 This suggests the presence of substantial overlap between the nitrogen lone pair and the P . ~orbital of the carbon atom and is consistent with the hindered rotation around the C-N bond as indicated by the inequivalence of the two N-methyl groups in 'H NMR (vide supra).
R
( 121 Schultz, A.J.;Stearley K. L; Williams, J. M.; Mink, R.; Stucky, G. D.Inorg. Chem. 1977,16,3303. 113)Teller, R. G.:Bau, R. Struct. Bonding (Berlin)1981,44,1. (14) ( a )Fischer, E.0.Adu. Organomet. Chem. 1976,14,1. lbi Gallop, M. A.; Roper, W. R. Adu. Organomet. Chem. 1986,25,121. ( c ) Brothers, P.J.; Roper, W. R. Chem. Reu. 1988. 88, 1293.td) Nugent, W. A.; Mayer, J. M. Metal-Ligand Multiple Bonds: John Wiley & Sons: New
York, 1988. 115)Hamilton, W.C.Acta Crystallogr. 1965,18,866.
Novel Synthetic Route to Mo Complexes
Organometallics, Vol. 14, No. 7, 1995 3373
The C-S distance of 1.755(1)A in l a is significantly longer than those (1.61-1.69 A)previously found for q2thiocarbamoyl complexes.6-8 In fact, this distance is substantially longer than the C=S double-bond distances of 1.55-1.56 A observed in CS2,16COS,17CSTe,18 and HNCS19 and 1.61 A in CH2=S20 and approaches the typical C-S single-bond distances of 1.78-1.82 A that have been observed in several thioethers.21 The Mo-C distance of 2.049(3) A is considerably shorter than the Mo-C single-bond distances of 2.2-2.4 A found in molybdenum alkyl complexes22and close to the range of Mo=C double-bond distances of 1.8-2.0 A reported for molybdenum alkylidene ~omp1exes.l~ Both the long C-S distance and the short Mo-C distance in l a indicate that the v2-thiocarbamoylligand has substantial carbenoid character as represented by
pounds 2a and 2b are remarkably stable toward thermal decomposition, as manifested by the high temperature at which they are synthesized. Only a few monomeric molybdenum terminal hydrosulfido complexes have been structurally c h a r a c t e r i ~ e d . ~ ~ The high-field region of the lH NMR spectrum of 2a in CDzClz displays a quintet resonance at 6 -3.98 ( 2 J ~ p = 6.7 Hz)which is assigned to the SH proton. The 31P{'H} NMR spectrum shows only a single resonance at 6 62.3. The 13C(lH}spectrum displays a very low-field binomial quintet resonance a t 6 266.5 ( 2 J ~ = p 18.4 Hz) which is assigned t o the carbyne carbon since this chemical shift is in the range typically observed for carbyne c0mp1exes.l~~ The NMR spectrosopic data of 2b are similar to those of 2a. The high-field region of the 'H NMR spectrum of 2b in c6& shows a quintet resonance at 6 -3.66 ( 2 J ~ NMe, = 7.1 Hz) which is assignable to the SH proton. The MOCCV 31P{1H}NMR spectrum displays a single resonance at \I S 6 56.6. The 13C(lH}spectrum shows a binomial quintet ~ Hz) assignable to the resonance a t 6 226.5 ( 2 J =~17.6 carbyne carbon. Synthesis and Spectroscopic Characterization All the NMR spectroscopic data of 2a and 2b are of Molybdenum Hydrosulfido-CarbyneComplexes trans- M o ( S H ) ( ~ C N M ~ ~ ) ( R ~ P C(R ~ ~=P Ph R ~ ) ~ consistent with an octahedral structure with a trans disposition of the hydrosulfido and aminocarbyne ligands, (2a), Et (2b)). When the red solutions of molybdenum as shown in eq 2. This trans geometry is adopted hydrido-thiocarbamoyl complexes l a and lb in toluene probably because the strong rc-acceptingcapacity of the were heated at 125 "C, greenish-yellow solutions were carbyne ligand24favors it being trans to the rc-donating formed, from which the molybdenum hydrosulfidohydrosulfido ligand. In contrast, the carbyne complex aminocarbyne complexes trans-Mo(SH)(=CNMez)(R2[ M O ( ~ C C ~ H ~ - ~ - M ~ ) ( C O ) ( P ~has ~ Pbeen C~H~PP~~) PC2H4PR212 (R = Ph (2a), Et (2b))were isolated as shown to adopt a cis octahedral structure in which the greenish-yellow solids in high yields (eq 2). carbyne and carbonyl ligands are cis t o each other due to the strong rc-accepting properties of both ligands.25 The IR spectra of 2a and 2b in Nujol mulls show weak bands at 2568 and 2571 cm-l, respectively, which are attributable to v(S-H). These v(S-H) stretching frequencies are in the range observed for conventional organic thiols.26 The v(C-N) bands for the aminocarbyne ligands appear at 1509 and 1497 cm-l, respecR = Ph (h), Et (2b) R = Ph (Is).Et (lb) tively, for 2a and 2b. Mechanism for the Thermal Rearrangement of Compounds 2a and 2b are obviously formed by l a and lb to 2a and 2b. A proposed mechanism for thermally induced rearrangement of l a and lb, respecthe thermal rearrangement of the hydrido-thiocarbamtively. To our knowledge, this represents a new synoyl complexes l a and lb to the hydrosulfido-aminocarthetic approach to carbyne complexes. Mononuclear byne complexs 2a and 2b is outlined in Scheme 1. The transition metal complexes containing terminally bound mechanism involves the initial migration of the hydride hydrosulfido ligands (SH) are relatively rare. Many of ligand from molybdenum to the sulfur atom of the the terminal hydrosulfido complexes tend to undergo thiocarbamoyl ligand to generate the 16-electron Fischer decomposition to form dimeric or cluster species concarbene intermediate Mo(=C(SH)NM~~)(R~PC~H~PR~)~, taining bridging SH or S2- ligands. In contrast, comfollowed by migration of the hydrosulfido group from (16)Guenther, A. H. J . Chem. Phys. 1959,31,1095. the carbene carbon to molybdenum to give the cis (17)Callomon, H. J.; Thompson, H. W. Proc. R. Soc. London, Ser. hydrosulfido-aminocarbyne complex which subsequently A. 1959,222,431. rearranges to the thermodynamically more stable trans (18)Hardv. W. A.: Silvev. G. Phvs. Rev. 1954.95.385. (19)Dousmanis, G.C.; Sanders,"T. M., Jr.; Townes, C. H.; Zeiger, isomer. Such a mechanism is plausible given the H. J. J. Chem. Phys. 1963,21,1416. precedents for transformation of aminocarbene into (20)Johnson, D. R.;Powell, F. X.; Kirchhoff, W. H. J. Mol. Spectrosc.
.:
1971,39,136. (21)(a) Maier, W. Angew. Chem. 1961, 73,120.(bl Frank, G. W.; Degen, P. J. Acta Crystallogr. 1973,B29, 1815.(c)Valle, G.;Busetti, V.; Mammi, M.; Carazzolo, G. Acta Crystallogr. 1969,B25, 1432.(dl Valle, G.; Busetti, V.; Mammi, M.; Carazzolo, G. Acta Crystallogr. 1969, B25, 1631.(el Fleming, J. E.; Lynton, H. Can. J . Chem. 1967.45,353. ( 0 Cunningham, G.L., Jr.; Boyd, A. W.; Myers, R. J.; Gwinn, W. D.; Le Van, W. I. J . Chem. Phys. 1951,19,676. (22)(a) Churchill, M. R. Perspect. Struct. Chem. 1971,3, 91.ibl Kirtley, S. W. In Comprehensive Organometallic Chemistry; Wilkinson, G., Stone, F. G. A., Abel, E. W., Eds.; Pergamon Press: Oxford, England, 1982;Vol. 3,Chapter 27.1.( C I Atwood, J. L.; Hunter, W. E.; Rogers, R. D.; Carmona, E.; Wilkinson, G. J . Chem. Soc., Dalton Trans. 1979,1519.td) KO,J. J.; Bockman, T. M.; Kochi, J. K. Organometallics 1990,9,1833.(el Prout, K.; Cameron, T. S.; Forder, R. A,; Critchley, S. R.; Denton, B.; Rees, G. V. Acta Crystallogr. 1974,B30, 2290.
(23)(a)DeSimone, R. E.; Glick, M. D. Inorg. Chem. 1978,17,3574. tb) Dupre, N.;Hendriks, H. M. J.; Jordanov, J. J . Chem. Soc., Dalton Trans. 1984, 1463. (c) Kamenar, B.;Korpar-Colig, B.; Cindric, M.; Penavic, M.; Strukan, N. J. Chem. Soc., Dalton Trans. 1992,2093.td) Kamenar, B.; Korpar-Colig, B.; Cindric, M.; Penavic, M.; Strukan, N. J. Chem. Soc., Dalton Trans. 1992,2093. (241( a ) Fischer, H.; Hofmann, P.; Kreissl, F. R.; Schrock, R. R.; Schubert, U.; Weiss, K. Carbyne Complexes; VCH Publishers: New York, 1988.tb) Mayr, A.; Hofheister, H. Adu. Organomet. Chem. 1991, 32,227.( c )Kim, H. P.; Angelici, R. J. Adu. Organomet. Chem. 1987, 27,51. (25)Dahlke, P.; Jeffery, J. C.; Mortimer, M. D. Polyhedron 1992, 11, 1587. 126)Patai, S., Ed. The Chemistry ofthe Thiol Group; Wiley: New York, 1974.
3374 Organometallics, Vol. 14, No. 7, 1995
Luo et al.
Scheme 1
Table 3. Crystallographic Data for trans-Mo(SH)(rCNMez)(PhzPCzHPPha)z(2a) empirical formula fw cryst syst space group a,A b, A C,
A
C~~H~~MONP~S 981.89 monoclinic P2 1lC 19.516(4) 12.301(2) 19.899(4) 102.46(3) 4665(2) 4 1.397 5.02 0.76-0.84 203 0.062 0.069
A
deg
v, A3
z
p(calcd), g ~ m - ~ ptMo Ka),cm-l midmax transmissn coeff
T,K R" RWb
R =1 1IFo/ - IFc/I/zlFol. R, = [ZwC lFol - IFcl)2/zwF~211'2.
aminocarbyne complexes, e.g., thermolysis of Cr(=C(X)NEt2)(C0)5 results in extrusion of one CO ligand and concomitant migration of the X group from the carbene carbon to chromium to give trun~-CrX(=CNEt2)(C0)4 (eq 3).27 "2
X
= SeR, TeR,C1, Br. 1.
X-ray Crystal Structure of Mo(SH)(WXWlez)(PhzPC2HPPhz)z (2a). The formulation of 2a as a hydrosulfido-aminocarbyne complex has been confirmed by a single-crystal X-ray diffraction study. A summary of the crystallographic data is given in Table 3, and the selected bond lengths and angles are given in Table 4. An ORTEP drawing is shown in Figure 4. Consistent with the solution NMR spectroscopic data (vide supra), the coordination geometry around the molybdenum atom in 2a is best described as a slightly distorted octahedron, with the two diphosphine ligands lying on the equatorial plane and the hydrosulfido and the carbyne ligands occupying the two trans apical positions. The least-squares plane of the aminocarbyne ligand defined by C, N, C(lc), and C(2c) is only slightly tilted with respect to the plane defined by Mo, C, P(2a), S, and P(2b), the dihedral angle formed by intersection (27)( a )Fischer, H.; Motsch, A.; Markl, R.; Ackermann, K. Organometallics 1985, 4 , 726. cb) Fischer, H.; Fischer, E. 0.; Himmelreich, D.; Cai, R.; Schubert, U.; Ackermann, K. Chem. Ber. 1981, 114,3220.
Figure 4. ORTEP drawing of trans-Mo(SH)(~NMez)(PhzPC&LPPh& (2a).
Table 4. Selected Bond Lengths (A)and Angles (deg)for truns-Mo(SH)(rCNMez)(PhzPCzH4PPhz)z (2a) Mo-P( l a ) Mo-P(2a) Mo-S C-N N- C(2 ~ ) P( la)-Mo-P( l b ) P(la)-Mo-P(2b) P( lb)-Mo-P(2b) P(l a )- Mo-S P(2a)-Mo-S P(la)-Mo-C P(2a )- Mo-C S-Mo-C C-N-C(lc) C(lc)-N-C(2c)
Bond Lengths 2.485(3) Mo-P(lb) 2.514(3) Mo- P(2b) 2.596(31 Mo-C 1.344(151 N-C(lc) 1.460(18) S-H Bond Angles P(la)-Mo-P(Ba) 1 7 8 . 2 I~ 98.7(1) P(lb)-Mo-P(Za) 80.8(1) P(Ba)-Mo-P(Zb) 86.7(1) P(lb)-Mo-S 79.2(11 P(Pb)-Mo-S 96.9(4) P(lb)-Mo-C 100.3(4) P(2bkM0-C 176.2(4) Mo-C-N 125.1(10) C-N-C(2c) 113.8(11) Mo-S-H
2.438(3) 2.504(3 1 1.830(111 1.422(20) 1.63 79.8~1) 101.1(1) 167.7(1) 95.1(1) 88.5(1) 81.3(4) 92.1(4) 175.1(8) 120.7(11) 95.5
of the two planes being 9.2". Since an orientation with a zero dihedral angle would be expected to maximize the n-bonding between the molybdenum and the aminocarbyne ligand, the slight tilting is probably caused by steric repulsion between the NMe2 group and the phenyl rings. The aminocarbyne ligand in 2a is nearly planar, all of its atoms (C, N, C(lc), C(2c))lying within 0.043 A of the calculated least-squares plane. This suggests the presence of substantial overlap between the nitrogen lone pair and a prrorbital of the carbyne carbon, which is substantiated by the short C-N distance of 1.34(2) A as compared to the N-C(lc) and N-C(2c) distances of 1.42(2) and 1.46(2) A,respectively. The Mo-C-N angle (175.1(8)")deviates slightly from linearity, which is not unusual for carbyne ligands.24 The Mo-C(carbyne) distance of 1.83(1) A is within the range previously reported for other molybdenum carbyne comple~es.2~ The Mo-S distance of 2.596(3) A in 2a unambiguously indicates a single bond between the molybdenum and sulfur atoms since the typical Mo=S double bond distances lie in the range of 2.08-2.13 A.2s It is noteworthy that the Mo-S distance in 2a is significantly 128)la) Bunzey, G.; Enemark, J. H. Inorg. Chem. 1978,17,682.ib) Huneke, J. T.; Enemark, J. H. Inorg. Chem. 1978, 17, 3698.
Novel Synthetic Route to Mo Complexes longer than the distances of 2.37-2.48 A previously reported for other mi ilybdenum terminal hydrosulfido c o m p l e ~ e s . "his ~~.~ ~ 1 engthening reflects the high trans influence of the cartyne ligandz4 on the hydrosulfido ligand. The hydrogon of the hydrosulfido ligand was located in the difference Fourier map but was not refined. The S-H di,stance is 1.63 A,and the Mo-S-H angle is 95.5'.
Conclusion
Organometallics, Vol. 14, No. 7, 1995 3375 Yield: 1.20 g (85%).Anal. Calcd for C55H55M~NP4S: C, 67.28; H, 5.64; N, 1.43. Found: C, 66.55; H, 5.60; N, 1.53. IR (Nujol): v(Mo-H) 1886 cm-', v(C-N) 1521 cm-'. 'H NMR (CsD&Ds, 298 K): d 6.85-7.50 (m, Ph), 2.69 (s,NCH3), 2.34 (s, NCHd, 2.21 (m, PCH2CH2P), 2.01 (m, PCHZCH~P), -3.66 (qnt, 'JHP = 37 Hz, Mo-H). 'H NMR (CeD5CD3, 188 K): d 6.80-7.70 (m, Ph), 2.33 (9, NCH3), 2.20 (m, PCHZCHZP),1.90 (m, PCH2CH2P),-4.10 (br d, 'JHP = 85 Hz, Mo-H). 31P{1H} NMR (CsD&&, 298 K): d 74.5 (s). 31P{1H}NMR (C&-CD3, 188 K): d 81.3 (d, VPp= 148 Hz), 77.2 (br s), 63.5 (br SI,61.4 (d, ' J p p = 148 Hz).
Synthesis of MoH(tlZ-C(S)NMez)(Et2PCzH4PEtz)2 (lb). We have found a nc )vel synthetic route to molybdenum truns-Mo(N2)2(Et2PC2H4PEt')2 (0.50g, 0.89 mmol) and HC(S)hydrido-thiocarbalrioyl and hydrosulfido-aminocarNMe2 (0.086mL, 1.06 mmol) in benzene (10 mL) were refluxed byne complexes. The, oxidative cleavage of the aldehydic for 25 min with a slow stream of argon sweeping through the C-H bond in NJV-diimethylthioformamideby trans-Moreaction flask (25 mL, with side arm) and exiting through the ( N ~ ) ~ ( R ~ P C ~ H(R~ = PR Z )Et) ~ affords the hydridoPh, reflux condenser. The resulting wine-red solution was cooled thiocarbamoyl compllexes M O H ( ~ ~ - C ( S ) N M ~ Z ) ( R ~ Pto C ~room ~ - temperature and evaporated in vacuo to dryness, PR2)2 (R = Ph (la), Et (lb)). Compounds l a and lb giving l b as a slightly tacky red solid which was contaminated with a small amount of unreacted HC(S)NMe2. The solid was undergo thermal re,srrangement to give the hydrosuldried at 55 "C in vacuo overnight and then scraped off the fido-aminocarbyne I :omplexes truns-Mo(SH)(@XMe2)bottom and wall of the reaction flask. Yield: 0.48 g (91%). ( R ~ P C ~ H ~ P(R R= Z )Ph ~ (2a),Et (2b)). This rearrangeThe product is extremely soluble in all common organic ment probably proceeds via migration of the hydride solvents. Anal. Calcd for C ~ ~ H ~ ~ M O N C,P46.23; ~ S : H, 9.28; ligand from molybcienum to the sulfur atom of the N, 2.34. Found: C, 46.81; H, 9.49; N, 2.20. IR (Nujol): vthiocarbamoyl ligar id to give the 16-electron Fischer (Mo-H) 1889 cm-', v(C-N) 1524 cm-'. 'H NMR (CsD5CD3, carbene intermediat .e M~(=C(SH)NM~~)(RZPC~H~PR~)~, 298 K): 3.42 (s,6 H, NCH3), 0.9-1.8 (m, 48 H, PCa4P, C a s ) , followed by migratjion of the hydrosulfido group from -6.44 (qnt, 2 J ~ = p 36.7 Hz, 1 H, Mo-H). 'H NMR (CsD5CD3, the carbene carbon t ,o molybdenum. Compounds 2a and 188 K): 3.20 (s,6 H, NCH3),0.8-1.9 (m, 48 H, P C ~ ~ca5), P , 2b represent rare examples of terminal hydrosulfido -6.77 (dm, 'JHP = 93 Hz, 1 H, Mo-H). 31P{1H)NMR (C&complexes which arl e remarkably stable toward thermal CD3, 298 K): b 63.5 (br s), 53.0 (br s). 31P{1H)NMR (C6D5CD3, 188 K): d 65.9 (d, 2 J p p = 41 Hz), 61.4 (d, ' J p p = 145 Hz), decomposition. We are currently exploring the synthetic 51.6 (d, ' J p p = 41 Hz), 49.0 (d, ' J p p = 145 Hz). scope of the reacticins described in this paper and the reactivity of the resulting molybdenum hydrido-thioSynthesis of ~~u~s-Mo(SH)(=CNM~Z)(P~ZPCZBPP~ (2a). A solution of MOH(~~'-C(S)NM~~)(P~~PC'H~PP~~)~ (la) carbamoyl and hyd rosulfido-aminocarbyne complexes.
Experimental Section General Procedures. All manipulations were performed either under a helium atmosphere in a Vacuum Atmospheres glovebox or under an argon atmosphere using standard Schlenk techniques unless otherwise specified. Solvents were distilled from sodiui n benzophenone ketyl and stored in a glovebox under heliltm. All deuteriated NMR solvents were distilled from CaH2. NJ-Dimethylthioformamide was purchased from Fluka and dried over 4-A activated molecular sieves before use. TI Le bis(dinitrogen)molybdenum complexes ~ ~ U ~ ~ - M O ( N Z ) ~ ( R(R ~ P=CPh, ~ HE~t )Pwere R Z )prepared ~ as described previously .3b 'H, 31P{1H},and ':C{'H} NMR spectra were recorded on a Bruker AM-200 spectrometer at 200.16,81.03,and 50.25 MHz, respectively; 'H and ' 3C chemical shifts were referenced to the solvent resonance remlative to TMS; 31Pchemical shifts were referenced to external 85% H3P04. Infrared spectra were recorded on a BioRrtd FTS-40 FT-IR spectrometer as Nujol mulls between KBr p labs unless otherwise specified. Elemental analyses were ptdormed using a Perkin-Elmer PE2400 CHN elemental analyzer. Synthesis of MolI(t12-C(S)NMez)(PhzPCzH4PPhz)z (la). truns-Mo(N2)2(Ph2PC:'H4PPh2)2(1.37 g, 1.44 mmol) and HC(S)NMe' (0.23 mL, 2.88 mmol) in benzene (20 mL) were refluxed for 25 min with a slow stream of argon sweeping through the reaction flask (50 mL, with side a n n ) and exiting through the reflux co ndenser. The resulting deep-red solution was cooled to room temperature and concentrated in vacuo to ca. 5 mL. Addition of hexane (30 mL) resulted in the precipitation of l a ias a red-brown solid, which was filtered off, washed with hrbxane ( 2 x 10 mL), and dried in vacuo. (29)( a ) Cragel, J., 4.0dF)). All calculations were conducted using the SHELXTLPlus software package.30
Luo et al. crystal having the approximate dimensions of 0.35 x 0.42 x 0.27 mm3 was selected, mounted on 6:glass i fiber with Apiezon "H" grease, and transferred to the goniostat cooled to -70 "C. Data were collected on a Enraf-Non IUS CAD4 diffractometer with graphite-monochromated Mo Ktx radiation (A = 0.710 73 A). Cell constants and an orientatioin matrix were obtained by least-squares refinement, using the setting angles of 25 randomly selected reflections. A tota 11 of 8588 reflections were collected (0 5 h 5 23, 0 5 k 5 14, - 2 5 5 1 5 25) in the range 2.14" < 26' < 54.88" with 7882 being >unique(R,,t = 7.49%).A series of high x (above 80")reflections were scanned to provide the basis for an empirical absorption correction with the transmission coefficient ranging fromi 0.76 to 0.84. No crystal decay was evident during the data clollection. The structure was solved by direct, methods and refined t o convergence by full-matrix least-squ ares methods. The calculated positions of the hydrogen atoms (except for the hydrogen of the hydrosulfido ligamd) were added to the structure factor calculations (C-H fixed at 0.96 A) but were not refined. The difference Fourier maps revealed the position of the hydrosulfido hydrogen. The fincal residuals for the fullmatrix least-squares refinement were R = 6.15%,R, = 6.89%, and GOF = 1.09 for 525 variable parameters and 3314 reflections (F> 4.0dIi3). All calculations were conducted using the SHELXTL-Plus software package 30
Acknowledgment. This work was performed under the auspices of the Division of Cheanical Sciences, Office of Basic Energy Sciences, Office of Energy Research, U.S.Department of Energy. WE!wish to thank Dr. Jeffrey C. Bryan (Oak Ridge National Laboratory) for helpful discussions.
Supporting Information Availahlle: Tables of crystallographic data, positional and thermal parameters, bond X-ray Crystallographic Analysis of ~FU~S-MO(SH)- lengths and angles, and atomic parameters of hydrogen atoms (=CNMez)(Ph2PC&PPh2)g(2a). Yellow crystals of 2a for l a and 2a (18pages). This materia.1 is contained in many suitable for X-ray diffraction measurements were grown by libraries on microfiche, immediately folLlows this article in the slowly cooling a saturated solution of 2a in hot toluene. A microfilm version of the journal, and can be ordered from the ACS; see any current masthead page for. ordering information. (30)SHELXTL-Plus; Siemens Analytical X-Ray Instruments, Inc.: Madison, WI, 1988. OM950159Y
