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A new dirbenium complex with an unsupported bridging hydride ligand
Polyhedron Vol. 7, No. 24, pp. 2543-2541, Printed in Great Britain
1988 0
0277-5387/H $3.00+.00 1988 Pergamon Press plc
A NEW DIRHENIUM COMPLEX WITH AN UNSUPPORTED BRIDGING HYDRIDE LIGAND RICHARD
D. ADAMS* and JONATHAN
D. KUHNS
Department of Chemistry, University of South Carolina, Columbia, SC 29208, U.S.A. (Received 22 April 1988 ; accepted 9 May 1988) Abstract-The reaction of Re2(CO),@-H), with CH2(NMe2)2 in chloroform at 25°C yielded the new compound Re,(CO),(NHMe,)(Cl)(p-H) (1) in 31% yield. Compound 1 was characterized by IR, ‘H NMR and a single-crystal X-ray diffraction analysis. Crystal data: orthorhombic, Pbca, a = 13.787(4), b = 19.884(5), c = 12.296(2) A. Solution by direct methods (MITHRIL), R = 0.035 for 1800 reflections. The complex contains two rhenium atoms linked by an unsupported hydride bridge, Re ***Re = 3.362(1)&Re(l)-H = 1.8(l) 8, and Re(2)-H = 2.0(l) A. A chloride ligand abstracted from the solvent is terminally bonded to Re(l), and a dimethylamine ligand abstracted from the CH2(NMe2)2 is coordinated to Re(2). When heated to 68”C, the dimethylamine ligand was eliminated and the chloride ligand became a bridge in the new compound Re2(CO),(p-H)&-Cl) (2), yield 76%.
Although there are a large number of polynuclear metal complexes that contain bridging hydride ligands, l-3 there are relatively few examples where the hydride ligand is the sole link between the metal atoms, A.“7
observed. In this report the reaction of Re2(CO),&H)2 with CH2(NMe2), is described. In contrast to our previous studies, the product of this reaction was found to contain a dimethylamine ligand in a new dirhenium complex that also contains a new example of an unsupported hydride bridge, A. EXPERIMENTAL
A
In our recent studies we have been investigating the reaction of bis-(dialkylamino)methanes with polynuclear metal carbonyl compounds that contain hydride ligands. We have found that the bis(dialkylamino)methanes are effective reagents for the introduction of secondary dialkylaminocarbene ligands, HCNR2, into the metal complexes by a carbonyl ligand replacement, eq. (1). 8-1’ HW,(W,+
CI-MNRJz - -co
HWPL
,W-Whl.
(1)
-Me2NH
It has been presumed that the transformation of bis-(dialkylamino)methane also yields secondary amines, R,NH, but these have not yet been
*Author to whom correspondence should be addressed.
GeneraI procedures and materials All reactions were performed under an inert atmosphere of prepurified nitrogen. The solvent CHC13 was dried by refluxing over P20s and was distilled just prior to use. The reagents Re2(CO)lo, Hz and (CH3)2NCH2N(CH3)2 were obtained commercially and were used without further purification. The complex H2Re2(C0)8 was prepared by the reported procedure. I2 TLC separations were performed in air on 0.25 mm Kieselgel 60 (W sensitized) F254 (E. Merck) purchased from Bodman Chemicals. IR spectra were recorded on a Nicolet 5 DXB FT IR spectrometer. ‘H NMR spectra were run on the Bruker AM-300 spectrometer operating at 300 MHz. Elemental analyses were performed by Desert Analytics, Tucson, AZ. Mass spectra were obtained on a VG Model 70 SQ spectrometer at 120°C with electron impact ionization at 15 eV.
2543
2544
R. D. ADAMS
Synthesis of Re2C1(CO)@HMeZ)(p-H)
(1)
H2Re,(CO), (68.3 mg, 0.11 mmol) was allowed to react with (0.08 cm3, 0.58 mmol) of CH2(NMe& in refluxing CHC13. The reaction was followed by IR for 15 min. The solution changed from pale yellow to colourless after 15 min. The solution was allowed to cool to room temperature and was then concentrated to a volume of 2 cm3 by a nitrogen purge. The product was separated by TLC (hexaneCH2C12, 1 : 1). Compound 1 is nearly colourless but was observed just above the base line under UV light. IR (v(C0) in CH,Cl,): 2118(w), 2100(m), 2019(vs), 1962(s) cm- ‘. ‘H NMR (6 in CDCl,): -13.19(s, lH), 2.97(d, 6H), JH_-H = 6.0 Hz. Mass spectrum for lB7Re m/e: 679-28x, x = O-8 (M+-8CO). Found: C, 17.9; H, 1.13; N, 2.02%. Calc. for 1: C, 17.7; H, 1.18; N, 2.07%. Synthesis of Re2(CO)&C1)@-H)
(2)
37.6 mg (0.056 mmol) of 1 was dissolved in 15 cm3 of hexane. Under a nitrogen purge the reaction solution was heated to reflux for 10 min. At this time the reaction was complete and was allowed to cool to room temperature. The solution was concentrated to 2 cm3 under a flow of nitrogen. This solution was then chromatographed by TLC with a hexan&HzClz, 1: 1 solvent mixture. The colourless product 2 was observed (under UV irradiation) as the fastest moving band and yielded 26.6 mg, 76%. For 2: IR (v(C0) in CH,Cl,) 2105(w), 2029(vs), 2005(m), 1968(s) cm-‘. ‘H NMR (6 in CDC13) -12.72(s, 1H). Mass spectrum for lE7Re m/e : 634 -28x, x = 0 - 8 (M+ - 8CO). Crystallographic analyses Colourless crystals of 1 were obtained by slow evaporation of solvent from a hexane-CH& solvent mixture at -20°C. The data crystal was mounted in a thin-walled glass capillary. DBrac-, tion measurements were made on a Rigaku AFC6 fully automated four-circle diffractometer using graphite monochromatized MO-K, radiation. The unit cell was determined and refined from 25 randomly selected reflections obtained by using the AFC6 automatic search, centre, index and least-
* Complete tables of bond lengths, angles, positional and thermal parameters for 1 and observed and calculated structure factors for 1 have been deposited as supplementary material with the Editor, from whom copies are available on request. Atomic coordinates have been submitted to the Cambridge Crystallographic Data Centre.
and J. D. KUHNS squares routines. Crystal data, data collection parameters and results of the analysis are listed in Table 1. All data processing was performed on a Digital Equipment Corp. MICROVAX II computer by using the TEXSAN structure solving program library obtained from the Molecular Structure Corp., College Station, TX. Neutral atom scattering factors were calculated by the standard procedures.13* Anomalous dispersion corrections were applied to all non-hydrogen atoms.‘3b Full-matrix least-squares refinements minimized the function :
Where w = l/a(I;?Z = &)/2&
o(F,z)= [(Iraw)* + (P&f)*l"*/Lp. Compound 1 crystallized in the orthorhombic crystal system. The space group Pbca was identified on the basis of the systematic absences observed during the collection of data. The coordinates of the heavy atoms were obtained by direct methods (MITHRIL). All remaining non-hydrogen atoms were subsequently obtained from a difference Fourier synthesis. All non-hydrogen atoms were refined with anisotropic thermal parameters. The bridging hydride ligand was located in a difference Fourier map and was successfully refined.* RESULTS
AND DISCUSSION
The reaction of H,Re,(CO), with CH,(NMe,), in refluxing chloroform yielded the product Re2(CO)&NHMe2)Cl@-H) (1) in 31% yield. Compound 1 was characterized by IR, mass spectral, ‘H NMR, elemental and single-crystal X-ray diffraction analyses. Interatomic distances and angles are listed in Tables 2 and 3, respectively. An ORTEP drawing of the molecular structure of compound 1 is shown in Fig. 1. The molecule contains two rhe-
Fig. 1. An ORTEP diagram of Re,(CO),(NHMed(Cl)gLH) (1) showing 50% probability thermal ellipsoids.
2545
A new dirhenium complex
Table 1. Crystallographic
data for diffraction study 1
Compound (A) Crystal data Formula Temperature ( f 3°C) Space group a (A) b (A) c (A) x (deg) B (deg) Y(deg) v (A’) M, z P (gem-?
Re2C10sNC10H, 23” Pbca, No. 61 13.787(4) 19.844(S) 12.296(2) 90.0 90.0 90.0 3364( 1) 677.0 8 2.67
(B) Measurement of intensity data Radiation Monochromator Detector aperture (mm) horizontal vertical Crystal faces Crystal size (mm) Crystal orientation direction ; deg from $J axis Reflections measured Max 28 (deg) o-scan width (deg) Scan type bkgd (count time at each end of scan) o-scan rate (deg min- ‘)” No. data used (F* > 3.0aF*)
Mo-& (0.71069 A) Graphite 2.0 2.0 100, TOO,010, OTO,001, OOT 0.06,0.23, 0.22 [OOl]; 2.3 +h, +k, +I 46 1.1 Moving crystal-stationary l/4 scan time 4.0 1800
counter
(C) Treatment of data Abs corr. Abs coeff. (cm- ‘) Transmission coeff. max min P-factor Final residuals % R
Goow&ess-of-fit Largest shift/error value of final cycle Largest peak in final diff. Fourier No. of variables
Analytical 154.1 0.379 0.044 0.02 0.035 0.040 2.15 0.09 0.99 202
“Rigaku software uses a multiple-scan technique. If the Z/u(Z) ratio is less than 10.0, a second scan is made and the results are added to the first scan, etc. A maximum of three scans was permitted per reflection.
2546
R. D. ADAMS and J. D. KUHNS Table 2. Intramolecular distances for 1 Atom
Atom
Distance
Atom
Atom
Distance
Re(1) Re(1) Re(1) Re(1) Re(1) Re(1) Re(1) Re(2)
Re(2) C(l1) C(14) H(1) C(13) C(12) Cl I-I(l)
3.363(l) 1.89(l) 1.95(2) 2.0(l) 1.99(2) 2.00(2) 2.481(3) 1.8(l)
b(2) Re(2) Re(2) Re(2) Re(2) N N 0
~(24) C(22) ~(23) C(21) N C(2) C(1) C(av.)
1.94(2) 1.95(2) 1.96(2) 1.99(2) 2.24(1) 1.46(2) 1.49(2) 1.13(2)
Distances are in angstroms. Estimated standard deviations in the least significant figure are given in parentheses.
nium carbonyl fragments that are linked by the bridging hydride ligand, H(1). The Re(1) * * * Re(2) distance at 3.363(l) w is much longer than that found in Re2(CO)ro, 3.041(l) A,14 but is similar to the Re-Re distance 3.392(2) 8, found in Re,Mn(CO)r4(p-H) which also contains an unsupported hydride bridge between two rhenium atoms. 7 These hydride bridges have been variously described as protonated forms of the metal-metal bonds of the corresponding anions B, ’ 5 or as coor-
,’
[ L,M’-
#’
‘\
‘*.
ML,
I-
dination complexes formed by the donation of an M-H bond of one fragment to a vacant site on
the metal atom of the second fragment, C. I4 These forms are simply limiting extremes of the more general three-centre two-electron bond D.’ However, form C would imply an unsymmetrical bonding for the hydride bridge while forms B and D H , \ a’
‘\
a’
8. ‘.
.’ L,M.._
______.
&IL,
D
would imply symmetrical arrangements. The ReH distances observed in 1 appear to be unequal, Re(2)-H(1) = 1.8(l) 8, and Re(l)-H(1) = 2.0(l) A, but the large standard deviations would preclude this difference as being significant. The Re-H-Re angle of 129(5)’ does appear to be significantly nonlinear as observed in other systems.2’3 The hydride
Table 3. Intramolecular bond angles for 1 Atom
Atom
Atom
co1)
Re(1) Re(1) Re(1) ReW Re(1) Re(1) Re(1) Re(1) Re(1) Re(1) Re(1) Re(1) Re(1)
C(14) H(1) C(13) C(W Cl I-I(l) C(13) C(12) Cl C(13) C(12) Cl C(12)
C(l1) C(l1) ml) cc11) C(14) C(14) C(14) C(14) H(1) I-I(l) I-I(l) C(13)
Angle 88.8(7) 84(2) 93.1(7) 89.2(7j
177.2(5) 166(3) 86.6(6) 91.2(6) 93.3(5) 106(3) 77(3) 94(2) 176.8(6)
Atom
Atom
Atom
Angle
C(13) C(12) H(1) H(lj I-I(l) I-I(l) H(1) C(2) C(2) C(1) Re(2) 0
Re(1) Re(1) Re(2) Re(2) Re(2) Re(2) Re(2) N N N H(1) C
Cl Cl ~(24) C(22) ~(23) C(21) N C(1) Re(2) Re(2) Re(1) Re(av.)
88.8(5) 89.0(4) 163(3) 94(3) 73(3) lW3) 84(3) 111(l) 117(l) 113(l) 129(5) 177(2)
Angles are in degrees. Estimated standard deviations in the least significant figure are given in parentheses.
A new dirhenium complex ligand exhibits the characteristic high field NMR shift, 6 = - 13.19 ppm. Each rhenium atom possesses a pseudo-octahedral coordination geometry with the ligands on one metal atom in a staggered conformational geometry with respect to the other. Each metal has four linear terminal carbonyl ligands with one positioned approximately trans to the Re-H bond. Re(2) contains a dimethylamine ligand, Re(2)--N = 2.24( 1) 8, while Re( 1) contains a chloride ligand, Re(l)-Cl = 2.481(3) 8, which was evidently abstracted from the CHC13 solvent. The tendency of metal-hydride complexes to abstract halogen atoms from halogenated hydrocarbons is well-known. ’6 The amine ligand in 1 is labile and was eliminated when 1 was heated to 125°C under a nitrogen purge. The product Re,(CO)&H)&-Cl) (2) was identified by IR, ‘H NMR, and mass spectral (parent ion m/e = 634 for “?Re with ions corresponding to the loss of each of eight CO ligands) analyses. It is believed to have the structure E with a bridging 0 C
__
0
C
OC\!./“\Je y” oc’cI ‘,/ I ‘co C
0
0
E
chloride ligand serving as a three-electron donor. The hydride ligand in 2 also exhibits the characteristic high-field NMR shift, 6 = - 12.72 ppm. AcknowledgementsAcknowledgement is made to the donors of the Petroleum Research Fund, administered by the American Chemical Society, for partial support of this research. The Briiker AM-300 NMR spectrometer
2547
was purchased with funds from the National Foundation, Grant No. CHE-8411172.
Science
REFERENCES A. P. Humphries and H. D. Kaesz, Prog. Znorg. Chem. 1979,25,145. R. Bau, Strut. Bond. 1981,44, 1. R. Bau, Transition Metal Hydrides, Adv. Chem. Ser., ACS, No. 167 (1978). B. Balbach, S. Barol, H. Biersack, W. A. Herrmann, J. A. Labinger, W. R. Scheidt, F. J. Timmers and M. L. Ziegler, Organometallics 1988, 7, 325. 5. J. Roziere, J. M. Williams, R. P. Stewart, Jr, J. L. Petersen and L. F. Dahl, J. Am. Chem. Sot. 1977, 99,4497.
6. K. S. Wong, W. R. Scheidt and J. A. Labinger, Znorg. Chem. 1979,18, 136. 7. H. D. Kaesz, R. Bau and M. R. Churchill, J. Am. Chem. Sot. 1967,89,2775.
8. R. D. Adams, J. E. Babin and H. S. Kim, J. Am. Chem. Sot. 1987,109,924.
9. R. D. Adams and J. E. Babin, Organometallics
1987,
6, 1364.
10. R. D. Adams and J. E. Babin, Organometallics
1988,
7, 963.
11. R. D. Adams and J. E. Babin, Polyhedron 1988, 7, 967.
12. M. A. Andrews, S. W. Kirtley and H. D. Kaesz, Znorg. Chem. 1977, 16, 1556.
13. International Tables for X-ray Crystallography, Vol. IV. Kynoch Press, Birmingham (1975) : (a) Table 2.2B, pp. 99-101, (b) Table 2.3.1, pp. 149-150. 14. M. R. Churchill, K. N. Amoh and H. J. Wasserman, Znorg. Chem. 1981,20,
1609.
15. M. R. Churchill, Transition Metal Hydrides, Adv. Chem. Ser., ACS, No. 167, p. 36 (1978). 16. R. A. Schunn, in Transition Metal Hydrides (Edited by E. L. Muetterties). Marcel Dekker, New York (1971).
1988 0
0277-5387/H $3.00+.00 1988 Pergamon Press plc
A NEW DIRHENIUM COMPLEX WITH AN UNSUPPORTED BRIDGING HYDRIDE LIGAND RICHARD
D. ADAMS* and JONATHAN
D. KUHNS
Department of Chemistry, University of South Carolina, Columbia, SC 29208, U.S.A. (Received 22 April 1988 ; accepted 9 May 1988) Abstract-The reaction of Re2(CO),@-H), with CH2(NMe2)2 in chloroform at 25°C yielded the new compound Re,(CO),(NHMe,)(Cl)(p-H) (1) in 31% yield. Compound 1 was characterized by IR, ‘H NMR and a single-crystal X-ray diffraction analysis. Crystal data: orthorhombic, Pbca, a = 13.787(4), b = 19.884(5), c = 12.296(2) A. Solution by direct methods (MITHRIL), R = 0.035 for 1800 reflections. The complex contains two rhenium atoms linked by an unsupported hydride bridge, Re ***Re = 3.362(1)&Re(l)-H = 1.8(l) 8, and Re(2)-H = 2.0(l) A. A chloride ligand abstracted from the solvent is terminally bonded to Re(l), and a dimethylamine ligand abstracted from the CH2(NMe2)2 is coordinated to Re(2). When heated to 68”C, the dimethylamine ligand was eliminated and the chloride ligand became a bridge in the new compound Re2(CO),(p-H)&-Cl) (2), yield 76%.
Although there are a large number of polynuclear metal complexes that contain bridging hydride ligands, l-3 there are relatively few examples where the hydride ligand is the sole link between the metal atoms, A.“7
observed. In this report the reaction of Re2(CO),&H)2 with CH2(NMe2), is described. In contrast to our previous studies, the product of this reaction was found to contain a dimethylamine ligand in a new dirhenium complex that also contains a new example of an unsupported hydride bridge, A. EXPERIMENTAL
A
In our recent studies we have been investigating the reaction of bis-(dialkylamino)methanes with polynuclear metal carbonyl compounds that contain hydride ligands. We have found that the bis(dialkylamino)methanes are effective reagents for the introduction of secondary dialkylaminocarbene ligands, HCNR2, into the metal complexes by a carbonyl ligand replacement, eq. (1). 8-1’ HW,(W,+
CI-MNRJz - -co
HWPL
,W-Whl.
(1)
-Me2NH
It has been presumed that the transformation of bis-(dialkylamino)methane also yields secondary amines, R,NH, but these have not yet been
*Author to whom correspondence should be addressed.
GeneraI procedures and materials All reactions were performed under an inert atmosphere of prepurified nitrogen. The solvent CHC13 was dried by refluxing over P20s and was distilled just prior to use. The reagents Re2(CO)lo, Hz and (CH3)2NCH2N(CH3)2 were obtained commercially and were used without further purification. The complex H2Re2(C0)8 was prepared by the reported procedure. I2 TLC separations were performed in air on 0.25 mm Kieselgel 60 (W sensitized) F254 (E. Merck) purchased from Bodman Chemicals. IR spectra were recorded on a Nicolet 5 DXB FT IR spectrometer. ‘H NMR spectra were run on the Bruker AM-300 spectrometer operating at 300 MHz. Elemental analyses were performed by Desert Analytics, Tucson, AZ. Mass spectra were obtained on a VG Model 70 SQ spectrometer at 120°C with electron impact ionization at 15 eV.
2543
2544
R. D. ADAMS
Synthesis of Re2C1(CO)@HMeZ)(p-H)
(1)
H2Re,(CO), (68.3 mg, 0.11 mmol) was allowed to react with (0.08 cm3, 0.58 mmol) of CH2(NMe& in refluxing CHC13. The reaction was followed by IR for 15 min. The solution changed from pale yellow to colourless after 15 min. The solution was allowed to cool to room temperature and was then concentrated to a volume of 2 cm3 by a nitrogen purge. The product was separated by TLC (hexaneCH2C12, 1 : 1). Compound 1 is nearly colourless but was observed just above the base line under UV light. IR (v(C0) in CH,Cl,): 2118(w), 2100(m), 2019(vs), 1962(s) cm- ‘. ‘H NMR (6 in CDCl,): -13.19(s, lH), 2.97(d, 6H), JH_-H = 6.0 Hz. Mass spectrum for lB7Re m/e: 679-28x, x = O-8 (M+-8CO). Found: C, 17.9; H, 1.13; N, 2.02%. Calc. for 1: C, 17.7; H, 1.18; N, 2.07%. Synthesis of Re2(CO)&C1)@-H)
(2)
37.6 mg (0.056 mmol) of 1 was dissolved in 15 cm3 of hexane. Under a nitrogen purge the reaction solution was heated to reflux for 10 min. At this time the reaction was complete and was allowed to cool to room temperature. The solution was concentrated to 2 cm3 under a flow of nitrogen. This solution was then chromatographed by TLC with a hexan&HzClz, 1: 1 solvent mixture. The colourless product 2 was observed (under UV irradiation) as the fastest moving band and yielded 26.6 mg, 76%. For 2: IR (v(C0) in CH,Cl,) 2105(w), 2029(vs), 2005(m), 1968(s) cm-‘. ‘H NMR (6 in CDC13) -12.72(s, 1H). Mass spectrum for lE7Re m/e : 634 -28x, x = 0 - 8 (M+ - 8CO). Crystallographic analyses Colourless crystals of 1 were obtained by slow evaporation of solvent from a hexane-CH& solvent mixture at -20°C. The data crystal was mounted in a thin-walled glass capillary. DBrac-, tion measurements were made on a Rigaku AFC6 fully automated four-circle diffractometer using graphite monochromatized MO-K, radiation. The unit cell was determined and refined from 25 randomly selected reflections obtained by using the AFC6 automatic search, centre, index and least-
* Complete tables of bond lengths, angles, positional and thermal parameters for 1 and observed and calculated structure factors for 1 have been deposited as supplementary material with the Editor, from whom copies are available on request. Atomic coordinates have been submitted to the Cambridge Crystallographic Data Centre.
and J. D. KUHNS squares routines. Crystal data, data collection parameters and results of the analysis are listed in Table 1. All data processing was performed on a Digital Equipment Corp. MICROVAX II computer by using the TEXSAN structure solving program library obtained from the Molecular Structure Corp., College Station, TX. Neutral atom scattering factors were calculated by the standard procedures.13* Anomalous dispersion corrections were applied to all non-hydrogen atoms.‘3b Full-matrix least-squares refinements minimized the function :
Where w = l/a(I;?Z = &)/2&
o(F,z)= [(Iraw)* + (P&f)*l"*/Lp. Compound 1 crystallized in the orthorhombic crystal system. The space group Pbca was identified on the basis of the systematic absences observed during the collection of data. The coordinates of the heavy atoms were obtained by direct methods (MITHRIL). All remaining non-hydrogen atoms were subsequently obtained from a difference Fourier synthesis. All non-hydrogen atoms were refined with anisotropic thermal parameters. The bridging hydride ligand was located in a difference Fourier map and was successfully refined.* RESULTS
AND DISCUSSION
The reaction of H,Re,(CO), with CH,(NMe,), in refluxing chloroform yielded the product Re2(CO)&NHMe2)Cl@-H) (1) in 31% yield. Compound 1 was characterized by IR, mass spectral, ‘H NMR, elemental and single-crystal X-ray diffraction analyses. Interatomic distances and angles are listed in Tables 2 and 3, respectively. An ORTEP drawing of the molecular structure of compound 1 is shown in Fig. 1. The molecule contains two rhe-
Fig. 1. An ORTEP diagram of Re,(CO),(NHMed(Cl)gLH) (1) showing 50% probability thermal ellipsoids.
2545
A new dirhenium complex
Table 1. Crystallographic
data for diffraction study 1
Compound (A) Crystal data Formula Temperature ( f 3°C) Space group a (A) b (A) c (A) x (deg) B (deg) Y(deg) v (A’) M, z P (gem-?
Re2C10sNC10H, 23” Pbca, No. 61 13.787(4) 19.844(S) 12.296(2) 90.0 90.0 90.0 3364( 1) 677.0 8 2.67
(B) Measurement of intensity data Radiation Monochromator Detector aperture (mm) horizontal vertical Crystal faces Crystal size (mm) Crystal orientation direction ; deg from $J axis Reflections measured Max 28 (deg) o-scan width (deg) Scan type bkgd (count time at each end of scan) o-scan rate (deg min- ‘)” No. data used (F* > 3.0aF*)
Mo-& (0.71069 A) Graphite 2.0 2.0 100, TOO,010, OTO,001, OOT 0.06,0.23, 0.22 [OOl]; 2.3 +h, +k, +I 46 1.1 Moving crystal-stationary l/4 scan time 4.0 1800
counter
(C) Treatment of data Abs corr. Abs coeff. (cm- ‘) Transmission coeff. max min P-factor Final residuals % R
Goow&ess-of-fit Largest shift/error value of final cycle Largest peak in final diff. Fourier No. of variables
Analytical 154.1 0.379 0.044 0.02 0.035 0.040 2.15 0.09 0.99 202
“Rigaku software uses a multiple-scan technique. If the Z/u(Z) ratio is less than 10.0, a second scan is made and the results are added to the first scan, etc. A maximum of three scans was permitted per reflection.
2546
R. D. ADAMS and J. D. KUHNS Table 2. Intramolecular distances for 1 Atom
Atom
Distance
Atom
Atom
Distance
Re(1) Re(1) Re(1) Re(1) Re(1) Re(1) Re(1) Re(2)
Re(2) C(l1) C(14) H(1) C(13) C(12) Cl I-I(l)
3.363(l) 1.89(l) 1.95(2) 2.0(l) 1.99(2) 2.00(2) 2.481(3) 1.8(l)
b(2) Re(2) Re(2) Re(2) Re(2) N N 0
~(24) C(22) ~(23) C(21) N C(2) C(1) C(av.)
1.94(2) 1.95(2) 1.96(2) 1.99(2) 2.24(1) 1.46(2) 1.49(2) 1.13(2)
Distances are in angstroms. Estimated standard deviations in the least significant figure are given in parentheses.
nium carbonyl fragments that are linked by the bridging hydride ligand, H(1). The Re(1) * * * Re(2) distance at 3.363(l) w is much longer than that found in Re2(CO)ro, 3.041(l) A,14 but is similar to the Re-Re distance 3.392(2) 8, found in Re,Mn(CO)r4(p-H) which also contains an unsupported hydride bridge between two rhenium atoms. 7 These hydride bridges have been variously described as protonated forms of the metal-metal bonds of the corresponding anions B, ’ 5 or as coor-
,’
[ L,M’-
#’
‘\
‘*.
ML,
I-
dination complexes formed by the donation of an M-H bond of one fragment to a vacant site on
the metal atom of the second fragment, C. I4 These forms are simply limiting extremes of the more general three-centre two-electron bond D.’ However, form C would imply an unsymmetrical bonding for the hydride bridge while forms B and D H , \ a’
‘\
a’
8. ‘.
.’ L,M.._
______.
&IL,
D
would imply symmetrical arrangements. The ReH distances observed in 1 appear to be unequal, Re(2)-H(1) = 1.8(l) 8, and Re(l)-H(1) = 2.0(l) A, but the large standard deviations would preclude this difference as being significant. The Re-H-Re angle of 129(5)’ does appear to be significantly nonlinear as observed in other systems.2’3 The hydride
Table 3. Intramolecular bond angles for 1 Atom
Atom
Atom
co1)
Re(1) Re(1) Re(1) ReW Re(1) Re(1) Re(1) Re(1) Re(1) Re(1) Re(1) Re(1) Re(1)
C(14) H(1) C(13) C(W Cl I-I(l) C(13) C(12) Cl C(13) C(12) Cl C(12)
C(l1) C(l1) ml) cc11) C(14) C(14) C(14) C(14) H(1) I-I(l) I-I(l) C(13)
Angle 88.8(7) 84(2) 93.1(7) 89.2(7j
177.2(5) 166(3) 86.6(6) 91.2(6) 93.3(5) 106(3) 77(3) 94(2) 176.8(6)
Atom
Atom
Atom
Angle
C(13) C(12) H(1) H(lj I-I(l) I-I(l) H(1) C(2) C(2) C(1) Re(2) 0
Re(1) Re(1) Re(2) Re(2) Re(2) Re(2) Re(2) N N N H(1) C
Cl Cl ~(24) C(22) ~(23) C(21) N C(1) Re(2) Re(2) Re(1) Re(av.)
88.8(5) 89.0(4) 163(3) 94(3) 73(3) lW3) 84(3) 111(l) 117(l) 113(l) 129(5) 177(2)
Angles are in degrees. Estimated standard deviations in the least significant figure are given in parentheses.
A new dirhenium complex ligand exhibits the characteristic high field NMR shift, 6 = - 13.19 ppm. Each rhenium atom possesses a pseudo-octahedral coordination geometry with the ligands on one metal atom in a staggered conformational geometry with respect to the other. Each metal has four linear terminal carbonyl ligands with one positioned approximately trans to the Re-H bond. Re(2) contains a dimethylamine ligand, Re(2)--N = 2.24( 1) 8, while Re( 1) contains a chloride ligand, Re(l)-Cl = 2.481(3) 8, which was evidently abstracted from the CHC13 solvent. The tendency of metal-hydride complexes to abstract halogen atoms from halogenated hydrocarbons is well-known. ’6 The amine ligand in 1 is labile and was eliminated when 1 was heated to 125°C under a nitrogen purge. The product Re,(CO)&H)&-Cl) (2) was identified by IR, ‘H NMR, and mass spectral (parent ion m/e = 634 for “?Re with ions corresponding to the loss of each of eight CO ligands) analyses. It is believed to have the structure E with a bridging 0 C
__
0
C
OC\!./“\Je y” oc’cI ‘,/ I ‘co C
0
0
E
chloride ligand serving as a three-electron donor. The hydride ligand in 2 also exhibits the characteristic high-field NMR shift, 6 = - 12.72 ppm. AcknowledgementsAcknowledgement is made to the donors of the Petroleum Research Fund, administered by the American Chemical Society, for partial support of this research. The Briiker AM-300 NMR spectrometer
2547
was purchased with funds from the National Foundation, Grant No. CHE-8411172.
Science
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