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Atom-Bridged Intermediates in N- and P-Atom Transfer Reactions.

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perature region the migration of the Pr3+ions from BR into mO
sites sets in, as mentioned above.
The ionic conduction behavior of Na+/Pr3+-/l”-Al,03 can
therefore be described as follows: At temperatures below 250 “C
an exchange of sites (from mO into BR positions) is only possible for those Pr3+ ions occupying mO positions, but a further
migration from the BR sites with lower coordination number is
not possible. Despite this partial mobility a continous current is
not detectable. because the ions trapped within the BR positions
interrupt the current transport. The observed conductivities at
these low temperatures are caused by residual, unexchanged
Na’ ions, which are able to pass through both sites without any
hindrance. Only above 250 “C are the Pr3+ ions completely mobile. These trivalent cations are now able to overcome all potential barriers along the conduction pathways. Consequently, ion
transport is detectable, and an increase in ionic conductivity
occurs (cf. Figure 3).
The above-mentioned transition temperature (T = 250 “C)
only holds for Na+/Pr3+-/3”-AIZOS
crystals with the composibecause of the pronounced
tion Na, oiPro,53Mgo,,2Allo,330i,
dependence of the height H , of the conduction layers on the
cation concentrat~on.[’~]
For steric reasons the extension of H L
in turn influences the size of the potential barrier that must be
overcome by ions leaving BR sites. Appropriate experiments to
investigate quantitatively the correlation of the cation concentration with the transition temperature are under way.
Received: June 10, 1996 [Z9210IE]
German version: Angew Chem. 1997, 109, 150- 152
Keywords: aluminum . conducting materials
lanthanides * solid-state structures
- ion mobility -
[I] J. Kohler, W. Urkdnd, 2.Anorg. A&. Chem. 1996, 622, 191.
[2] F. Tietz. W. Urland. Solid Sture Ionics 1995, 78, 35.
[3] G. C. Farrington, B. Dunn, J. 0. Thomas, Appl. Phys. A 1983,32, 159.
141 J. Kohler. W. Urland, 2.Anorg. Allg. Chem. 1996, in press.
[5] T. Dedecke. J. Kohler, F. Tietz, W. Urland, Orr. J Solid State Inorg. Chem.
1996.33, 185
161 J Kohler, Dmerturion, Universitat Hannover, 1996.
[7] J. Kohler, W. Urland, Solid State Ionics 1996,86-88, 93.
[8] N. Imanaka, Y. Kobayashi, G. Adachi, Absr. 10th Int. Conf: Solid State lonics,
Singapore. 1995.407; N. Imanaka, Y Kobayashi, G. Adachi, Chem. Lett. 1995,
433.
[9] In these investigations the crystal structure of a selected Na+/Pr’+-/l’-Al,O,
crystal with known composition is determined on the four-circle diffractometer
at different temperatures. The temperature-dependent measurements are performed with an Enraf-Nonius-goniometer and the mountable crystal furnace
F R 559. For an exact temperature control the crystal furnace is calibrated with
an external Pt/Rh thermocouple as well as by melting point determinations of
the low melting metals In, Sn, Pb, Zn, and Al
[lo] M. Bettman. C. R Peters, J Phys. Chem. 1969, 73, 1774.
[ l l ] B. Dunn, G C . Farrington, Solid State lonics 1983, 9/10, 223.
[12] S. Sattar, B. Ghosal. M. L. Underwood, H. Mertwoy, M. A. Saltzberg, W S.
Frydrych, G. S Rohrer. G. C. Farrington, J Solid Stare Chem. 1986,65, 31 7.
I
Muter. Sci. 1983, 18, 2437
[13] F. Harbach. .
[14] J. Kohler, W. Urland, J SolidState Chem. 1996, 124, 169.
[15] J. Kohler, W. Urland, J Solid State Chem., in press.
[I61 Na+-/Y’-AI,O, crystals are grown (flux evaporation method) by slowly evaporating the Na,O flux at nearly 1700°C. The complete ion exchange with Pr3+
ions is obtained by immersing the Na+-/l’-AI,O, crystals into molten anhydrous PrCl, for 2 - 3 hours a t 790 “C (inert gas atmosphere).
[17] The crystal composition and the degree of exchange 5 ( 5 refers to the original
N a + content of the employed Na+-P”-AI,O, crystal) are determined by electron probe microanalysis
[I81 Crystal structure data of P r ’ + - ~ - A I , O , for some selected temperatures.
Siemens-AED-2-Diffractometer, Mo,,, i.~ 7 1 . 0 pm,
7 graphite monochromator, 0-20 scan. Lp and numerical absorption correction, anisotropic refinement with SHELXL-93. a) Measurement at room temperature: space
group RJm (No. 166). Z = 3, a = 563.50(28), c = 3337.7(17) pm, V =
916.99 x 10’ pm’. pGd,cd
= 3.480 gcm-’, 20,,, = 45.97”, 0-20 scan, 1713 measured reflections. 201 symmetry independent reflections, 196 reflections with
Angew Chrm Int Ed End 1997, 36. No 112
10>40(1,), 48 refined parameters, R values (all reflections) RIIFI = 0.0433,
M.RZ/F*J= 0.1096, minimax Ap = - 0.67/3.08 e ~ m x-10.
~
b) Measurement at 322 ”C: u = 564.26(35), c = 3345.7(17) pm. V = 922.52 x 10‘ pm’,
pcalod
= 3.462 gcm-’, 2R,,
= 45.88”, w-2R scan, 1708 measured reflections,
201 symmetry independent reflections, 201 reflections with I, >4u(lo), 45 refined parameters, R values (all reflections): R1 IF1 = 0.0756. 12.R21FZI=
0.1947, min/max Ap = -1.17:1.27epm-’x lo-‘. c) Measurement at
=
471 ‘C: u = 565.87(36), c = 3350.1(20) pm. V = 929.01 x 10‘ pm’. prdlrd
3.438 gcm-’, 20,,, = 59.87”, 0)-20 scan, 3400 measured reflections. 388 symmetry independent, 365 reflections with I0>4u(lO), 50 refined parameters,
R values (all reflections): R l l F = 0.0704, wR21F’I = 0.1938, minimax
A p = - 1.06/1.06 epm-’ x
Further details of the crystal structure investigations may be obtained from the Fachinformationszentrum Karlsruhe,
D-76344 Eggenstein-Leopoldshafen (Germany), on quoting the depository
numbers CSD-405335 (crystal a), CSD-405334 (crystal b) and CSD-405333
(crystal c)
Atom-Bridged Intermediates in N- and P-Atom
Transfer Reactions**
Marc J. A. Johnson, P. Mae Lee, Aaron L. Odom,
William M. Davis, and Christopher C. Cummins*
Complete intermetal N-atom transfer reactions constitute
highly economical three-electron redox processes.[” A seminal
reaction of this type is the reduction of [NMn(TTP)]
(TTP = meso-tetrakis(4-toly1)porphyrin) by [Cr(TTP)] to give
[Mn(TTP)] and [NCr(TTP)] .[‘I Certain quasi-degenerate intermetal N-atom transfer reactions have been subjected to kinetic
studies to delineate energetic parameters innate to the atomtransfer event.‘21Evidence has been amassed regarding the role
of N-atom-bridged species as intermediates in N-atom transfer
reactions, but until now such intermediates have eluded characterization.”]
It was found recently[31that the three-coordinate molybdenum(rI1) complex 1[3-’1 effects N-atom abstraction from the ni71 and (under argon) 0.5 equivtrido complex 2[’] to give 3
[Mo(NRAr),]
1, R
[NMo(O-fBu),]
2
[NMo(NRAr),]
3
[Mo,(O-rBu),]
“[Mo(O-tBu),]”
=
C(CD,),CH,, A r
=
3,5-C,H3Me,
4
5
[(tBuO),Mo(g-N)Mo(NRAr),]
6
alents 4[9*’01or (under 1 atm dinitrogen) predominantly 2.
Products 4 and 2 appear to result from dimerization and dinitrogen cleavageJ5.’1 respectively, stemming from transient 5,which
was not observed. During N-atom abstraction from 2 by 1,
a blue color was observed that was tentatively attributed to
the intermediate complex 6.‘” Here we report that in a closely
related reaction system, the teal N-atom bridged species 7
(R = C(CD,),CH,, Ar, = 4-C6H,F, [Eq. (I)]) produced upon
[*] Prof. C. C. Cummins, M. J. A. Johnson, P. M. Lee, A. L. Odom,
Dr. W. M. Davis
Room 2-227, MIT Department of Chemistry
Cambridge, MA 02139-4307
Fax: Int. code +(617)253-7030
e-mail: ccummins@,mit.edu
[**I
For funding C. C. C. thanks the National Science Foundation (CAREER
Award CHE-9501992), DuPont (Young Professor Award), the Packard Foundation (Packard Foundation Fellowship), Union Carbide (Innovation Recognition Award), and 3M (Innovation Fund Award). M. J. A. J isgrateful for an
NSERC graduate research fellowship.
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R
in this regard." The C,-symmetric conformation of the Mo(NRAr,), moiety in 7 is as observed previously for several [XM(NRAr),] molecules;['. 14, l5] the apical group X is commonly located in the pocket presented by the three groups R, and the
three aryl groups pack tightly in a trigonal construction that
protects the opposite hemisphere of the complex. Conversion of
7 to the putative transient 10 and the terminal nitrido complex
11 represents the complete intermetal N-atom transfer process
for this reaction system. Thermal transformations of 7 are currently under scrutiny.
mixing equimolar quantities of 8 and 9 is relatively robust in
solution (toluene o r ether) at low temperatures (ca. 20 "C or
below).
An ORTEP drawing of the structure of 7 is presented in
Figure I.["] Salient features of the structure are a linear p nitrido bridge[". 131 and crystallographic threefold symmetry
"[Mo(NMe,),]"
10
[NMo(NRAr,),]
11
Evidence for complete N-atom transfer was obtained in a
related system as follows: a single crystal obtained by cooling a
had been
solution in which equimolar quantities of 8 and
~
Figure 1 Crystal structure of 7 (ORTEP diagram). For a discussion of the disordered NMe, groups see ref. [11] and text. Selected bond lengths [A] and angles
Mo(l)-N 1.82(4), Mo(l)-N(l) 1.977(10), Mo(2)-N 1.83(4), Mo(2)- N(2)
1.969(13), N(2)-C(22) 1 36(4), N(2)-C(24) 1.39(5), N(2)-C(21) 1.42(4), N(2)C(23) 1.50(5); N-MO(1)-N(1) 103.9(3), N(l)'-MO(l)-N(l) 114.4(2), N-M0(2)-N(2)
108.9(4), N(2)'-Mo(Z)-N(2) 110.0(4), Mo(l)-N-Mo(Z) 180.0.
r]:
about the Mo(p-N)Mo axis. Disorder of the (Me,N),Mo
moiety about the threefold axis was accounted for by a model in
which one dimethylamido group is oriented with its NC, plane
perpendicular to the molecular threefold axis, and the other two
NMe, groups adopt a parallel orientation thereto.["] In this
model, although each molecule of 7 conforms to C , point symmetry, three equally probable orientations of 7 in the unit cell
result in crystallographic threefold symmetry and the observed
disorder. Observation of the C,-symmetric structure of 7 as
opposed to an alternative C,-symmetric structure can be at)~
tributed to a Jahn-Teller distortion for this ( I K , ) ~ ( I K ,system.
Although the p-nitrido nitrogen atom appears to be symmetrically disposed between the inequivalent Mo centers, relatively
high esd's associated with this atom prohibit a firm conclusion
88
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[Mo(NtBuPh),]
[Mo,(NMe,),l
12
13
[(Me,N),Mo(~-N)Mo(NMe,),l
14
combined at 28 "C was studied by X-ray crystallography and
found to contain a 1 :1 mixture of known dimer 131'6-'81and
the symmetrical w-nitrido complex 14 (Figure 2).[Ig1The structure -of dimer 13 is as reported previously.[' 71 More
intriguing is the structure of
p-nitrido-bridged complex
14, which may be considered the product of reaction
between transient 10 and
the terminal nitrido complex 8 (Scheme 1). The
p-nitrido nitrogen atom in
14 resides at a crystallographic inversion center,
which when combined with
the absence of a crystallographic threefold axis along
the linear Mo(p-N)Mo vector leads to the point group
Figure 2. Crystal structure of 14
assignment C, for the
(ORTEP diagram). Selected bond
molecular complex 14. In
lengths [A] and angles ["I: Mo(1)-N(1)
1.7990(8),
MO(l)-N(3)
1.948(9),
principle less-favored for 14
Mo(1) -N(S)
1.953(8), Mo( l)-N(7)
would be more symmetrical
1.9.55(8); N(I)-Mo(l)-N(3) 100.1(3),
S , and D,, structures, inN(1)-Mo(1)-N(5) 99.4(2), N(3)-Mo(l)N(5)
116.6(4).
N(I)-Mo(l)-N(7)
voking the Jahn-Teller the100.0(3), N(3)-Mo(l)-N(7) 117.3(4),
c , )as
~
orem for ( l ~ c , ) ~ ( l ~14
N[S)-Mo(l)-N(7) 117.6{3).
for 7 above. The unique
Mo-p-N distance in 14 corresponds approximately to bond order two. The geometry at
molybdenum is pseudotetrahedral. From a chemical point of
view 14 is probably best regarded as a source of putative transient 10, since disintegration of either Mo-p-N linkage would
produce 10 along with the terminal nitrido complex 8. Dimerization of 10, in which the Mo center is three-coordinate, would
produce 13 (Scheme 1).
The symmetrical p-nitrido complex 14 was isolated in pure
form by treatment of 12 with two equivalents of 8 (see Experimental Section). Complex 14 exhibits a single broad 'H NMR
signal at about 6 = 7 in C,D, at 22 "C, and the compound transforms smoothly to give a mixture of dimer 13 and the terminal
nitrido complex 8 upon stirring under N, (1 atm) at 28 "C for
90 min, as assayed by 'H and 13C NMR spectroscopies.
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Angew. Chem. Inf Ed. Engl. 1997. 36, No. 1/2
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I
Me
\
+a, -35 oc
Me
N
25 "C
I
Et20, -8
Me
10
Me
Mk
14
I
Me
Me
13
Scheme 1. Possihle rcactions involving the participation of the putative transient
10
Robust terminal phosphido (P' -) complexes were discovered
recently.[6.20. ' I One might suspect that these heavy analogues
of terminal nitrido complexes are equipped to engage in intermetal P-atom transfer processes. Accordingly, we find that mixing equimolar quantities of 1St6]and 12''' in toluene leads to
[PMo(NRAr),]
15
16
[PMo(NrBuPh),]
reversible P-atom transfer at 25°C; 31P NMR signals were observed at 6 = 1216 and 1226 for terminal phosphido complexes
15 and 16, respectively. Cooling an equimolar mixture of 12 and
16 in toluene to - 35 "C elicits a color change from red-brown to
purple [Eq. (211 that is reversible upon repeated warming and
t-Bu
Figure 3. Crystal structure of 17 (ORTEP diagram). Selected bond lengths [A] and
angles ['I: Mo-N(1) 1.990(6), Mo-N(2) 1.992(6). Mo-N(3) 1.993(6), Mo-P
2.2430(6); N(l)-Mo-N(2) 113.8(2), N(l)-Mo-N(3) 110.6(2). N(2)-Mo-N(3)
112.4(2), N(l)-Mo-P 106.2(2), N(2)-Mo-P 106.2(?), N(3)-Mo-P 107.2(2), Mo'-PMo 180.0.
16 are 2.1 19(4) and 2.1 1l(2) A, respectively. Based on the MoP distances in 17 and on the probable electronic configuration
of its Mo(p-P)Mo x system, specifically ( I 7 ~ ~ ) ~ ( l ax Mo-P
J~,
bond order of two follows for the complex. Metrical parameters
for 17, apart from those associated with the phosphorus atom,
indicate that little reorganization takes place during its formation.
The findings communicated here conclusively implicate
atom-bridged species as intermediates in intermetal N- and Patom transfer reactions involving the Mo"'/MoV' redox couple.
Energetic parameters pertaining to these overtly simple transformations are now open for inquiry. Especially appealing is the
synthetic utility these transformations may offer in generating
reactive transients such as the putative monomer [Mo(NMe,),]
(10).
Experimental Section
12
Ph
+
Th
-
Ph
30 "C
___t
-35 "C
P
I
Ph
Ph
Ph
17
16
cooling cycles. The purple color is attributed to the symmetrical
bridging phosphido[2z1complex 17, which has been isolated and
characterized by X-ray crystallography (Figure 3)
Complex 17 possesses Ci symmetry in the crystal, reminiscent
of the structure of the pnitrido complex 14. In fact, the description of 14 given above applies in many respects to 17. The
disposition of planar NC, fragments relative to the linear Mo(p-E)Mo (E = N or P) core is very similar in the two complexes.
Two molybdenum atoms at 2.2430(6) A flank the symmetrically
bridging phosphorus atom in 17; the Mo-P distances in 15 and
Anyew. C h w . lnr. Ed. G I ~ I 1997,
.
36, No 112
G
General: All manipulations were performed in a Vacuum Atmospheres glovehox
under a n atmosphere ofdry nitrogen unless otherwise indicated. Solvents were freed
from air and moisture by using standard procedures.
7: 8 (120 7 mg, 0.4984 mmol) and 9 (301.3 mg, 0.491s mmol) were mixed as solids
in a 20 m L scintillation vial. To the mixture was added ether (20 mL) at 28 "C, while
stirring vigorously. After about 10 s, the resulting dark blue-green homogeneous
solution was placed in a freezer ( - 35 T).Over a period o f 4 h, dark green crystals
and powder Separated from the solution. The solid product was collected by filtration on a sintered glass frit and dried in Yacuo (309.4 mg, 0.3619 mmol, 73.59%).
~ 14 Hz); I9F NMR (282 MHz,
* H N M R (46 MHz, C,H,, 22 C): 6 = 5.49 ( A P , , =
C,D,, 22 T):6 = - 113.0(Av,., = 160 Hz).pcfl(SQUID, 5--300 K ) . 1.56 p8. Anal.
C 50.58, H 6.72, N 11.47; found: C 50.74; H 6.62,
calcd for C,,H,,D,,F,N,Mo,:
N 11.50.
8: Colorless needles of 2 (2.59 g, 7.87 mmol) were slurried in toluene (50 mL).
Yellow-gold [Ti(NMe,),] (1.33 g, 5.93 mmol, 0.754 equiv) was added and rinsed in
with additional toluene (10 mL). The reaction mixture acquired a light orange color
and became homogeneous in less than 5 min. The color faded to pale yellow during
the next several minutes, and the reaction solution was stirred for a total of 3 h A
'H NMR spectrum (C,D,) of an aliquot exhibited singlets for [Ti(O-/Bu),] and 8 at
6 =1.35 and 3.29, respectively. The reaction mixture was placed in the freezer
( - 35 C), whereupon pale-yellow crystals formed. The crystals were isolated by
filtration on a sintered glass frit. washed with pentane, and dried in >acuo (two
crops: 1.53 gand0.1576 g,6.97mmol,88.6%). ' H N M R ( 3 0 0 M H z . C , D 6 , 2 3 ,C)b = 3.293 (s); " C NMR (75 MHz. C,D,, 23 "C): b = 51 19 (9,J = 134 Hz). Anal.
calcd for C,H,,N,Mo: C 29.76, H 7.49. N 23.13: found. C 29 44, H i.50. N 23.02
9: White (Li(NRAr,)(OEt,)] was prepared according to the published procedure for
[Li(NRAr)(OEt,)]. substituting 4-fluoroaniline for 3.5-dimethylaniline. A solution
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of [Li(NRAr,)(OEt,)] (5.10 g, 20.1 mmol, 2.01 equiv) in diethyl ether (160 mL) was
chilled until frozen, and then allowed to thaw at 28°C. To the thawing mixture was
added [MoCl,(thf),] 124-261 (4.20 g, 10.0 mmol). The resulting orange suspension
was stirred and, after 30 min, rapidly acquired a brown color. ,H NMR spectra
indicated an extent of reaction of70% after 90 min, and greater than 80% after 2 h.
The mixture was filtered through Celiteon a frit after 3 h, and all volatile matter was
removed from the filtrate. The crude dark brown powder was dissolved in diethyl
ether (12 mL), and the solution was sparged with argon prior to storage in a tightly
capped vessel at - 35 "C overnight. Green-tinted yellow-brown powder was isolated
by filtration on a sintered glass frit (two crops, 2.16g. 3.53 mmol, 52.8%). M.p.
130-132°C (decomp). ' H N M R (300MHz, C,D,, 23°C): 6 = 68.88 (v br s, 9H,
~ 900 Hz), 22.75 (br s, 6H, meta-C,H,F, A v I t 2=130 Hz),
C(CD,),CH,, A V , , =
-27.31 (v br s, 6H, ortho-C,H,F, Avli2 = 530 Hz); 2H NMR (46 MHz, Et,O,
22°C): 6 = 69.37 (Av,;, = 36 Hz); "F NMR (282 MHz, C,D,, 22'C): 6 = 24.76
(AvIi, = 600 Hz). pcff(Evans' method, 300 MHz, C,D,, 21 .O "C) = 3.74 p L e Anal.
.
calcd for C,,H,,D,,F,N,Mo~ C 58.81, H 6.42, N 6.86; found: C 58.80, H 6.61, N
6.72.
11: Dark yellow powdery [Mo(NRAr,),] (11 1.3 mg, 0.1817 mmol) was dissolved in
diethyl ether ( 5 mL), producing a clear orange solution, to which was added neat
pale yellow inesityl azide [27] (38 pL, 0.26 mmol, 1.4 equiv). The reaction mixture
rapidly acquired an intense purple color, and vigorous effervescence occurred for
approximately 15 s, during which time the solution became dark forest green. The
mixture was stirred for a further 4 h, then solvent was removed in vacuo. The
resulting dark green solid was dissolved in hexamethyldisiloxane (ca. 8 mL) and
cooled to - 35 "C. Fine off-white crystals formed (two crops, 74.3 mg, 0.1 19 mmol,
65.2%). 'H NMR (499.7 MHz, CDCI,, 22 "C): 6 = 6.70 (pseudo triplet, 2H, meta),
5.97 (br dd, 2H, ortho), 1.36 (s, 3H, C(CD,),CH,); '3C{'H] NMR (75 MHz,
CDC13,23'C):6 =160.67(d, J(C,F) = 246.0Hz,pura), 146.08(s,ip.w), 131.50(d,
J(C,F) = 8.1 Hz, ortho), 114.75 (d, J(C,F) = 21.8 Hz. meta), 61.34 (m,
C(CD,),CH,), 32.68 (s, C(CD,),CH,). 32-16 (m, C(CD,),CH,); I3C NMR (75
MHz, CDCI,, 23°C): 6 =160.67 (d m,para), 146.08 (t, ipso), 131.50 (doublet of
pseudo triplets, ortho), 114.71 (ddd, meta), 61.34 (br, C(CD,),CH,), 32.66 (q,
C(CD,),CH,), ca 32.15 (m. C(CD,),CH,). Anal. calcd forC,,H,,D,,F,N,Mo:
C
57.50, H 6.27, N 8.94; found: C 57.21, H 6.21, N 8.80.
14: A dark orange-brown solution of 12 (101.9 mg, 0.1885 mmol) in diethyl ether
(2 mL) was added to a yellow solution of 8 (90.8 mg, 0.375 mmol, 1.99 equiv) in
diethyl ether (6 mL) at 28 "C. The resulting dark teal mixture was stirred rapidly and
sparged with argon for 30 s before the vial was capped tightly. taped, and placed in
a freezer at - 35 "C. Large black blocks formed at the bottom of the vial over several
hours; an orange plate of [NMo(NrBuPh),] (18) formed on the side of the vial
above the surfxe of the dark teal mother liquor. The solution was decanted
and the crystals were dried under vacuum. The single crystal of 18 remained apart
from the dark blocks, which are presumed to consist largely of 14 (50.1 mg,
0.1864 mmol, 57.1 %); neither 8 nor 13 was observed in the 'H NMR spectrum of
the isolated product. 'HNMR (500 MHz, C,D,, 22°C): 6 =7.13 (Av1,, =74 Hz)
Anal. calcd for C,,H,,N,Mo,: C 30.64, H 7 71, N 20.85; found: C 31.69, H 7.38,
N 20.79. Chemical characterization: dark shiny crystals of 14 (40.2 mg,
0.0855 mmol) were placed in a small glass vessel to which just-melted ether was
added The vessel was sealed under nitrogen and allowed to warm to 28 "C while
the mixture was stirred. The initially dark teal solution acquired a green hue
over about 5 min, and became brown within 90 min, at which point volatile
material was removed. 'H and I3C{'H} NMR spectra indicated the presence of 13
and 8 in a 1:4 mole ratio as follows: 'HNMR (300 MHz, C,D,. 23°C). 6 = 3.42
(br s, 13), 3.29 (s, 8); I3C{'H} NMR (75 MHz, C,D,, 40.3 "C): 6 = 51.15 (8), 49.72
(br, 13). No signals attributable to (NtBuPh)-containing compounds were observed.
14: Preparation of 1: 1 co-crystal with 13. Orange 12 (242.1 mg, 0.4478 mmol) and
pale yellow 8 (108.1 mg, 0.4464 mmol) were combined in a 20 mL scintillation vial,
and diethyl ether (6 mL) was added at 28 "C. The mixture was agitated until it
became homogeneous and dark teal in color (ca. 45 s). The vial was then capped and
stored for 5 d at - 35 "C. Crystals of two morphologies separated from the solution:
a) large clear pale orange crystals characteristic of 18, and b) small, dark green
blocks. A crystal of type b was investigated by X-ray diffraction and found to be a
1 : 1 cocrystal of 14 and 13.
17: Yellow crystals of 16 (108.0 mg, 0.189 mmol) and wine-red crystals of 12 171
(102.3 mg, 0.189mmol) were added to ether (10 mL, argon-sparged) in a 20mL
scintillation vial, and the vial was tightly capped after sparging the mixture with
argon. The mixture was warmed to 28 "C to ensure complete dissolution of the
complexes. The vial was then placed in a freezer ( - 35 "C), whereupon the solution
adopted an intense purple color. Crystals of dark purple 17 formed over several
hours (158.9 mg, 75.6%). Crystals suitable for a single-crystal X-ray diffraction
study were obtained by recrystallization from argon-sparged ether by slow cooling
to -35°C in an insulated vessel. 'HNMR (300 MHz, C,D,, -40°C)- 6 =14.20
(Avli2 =75 Hz, 6H, C,H,), 13.95 (Av,:, = 35 Hz, 6H, C,H,), 8.95 ( A V ~=; ~17 Hz,
6H, C,H,), 8.65 (Av,i2 = 36 Hz, 54H, C(CH,),), 6.10 (Av,,, = 21 Hz, 6H, C,H,),
~ 36 Hz, 6H, C,HJ
pCrr (Evans' method, 300 MHz, C,D,,
4.84 ( A V , ;=
-76"C)=2.08pc,,pc,,(SQUID, 5-300 K)=1.75pB.
Received: June 27, 1996 [Z 9263 IE]
German version: Angew. Chem. 1997, 109, 110- 113
90
0 VCH Verlagsgesellschuft mbH, 0-69451 Weinheim, 1997
-
Keywords: atom-transfer reactions molybdenum * N ligands
P ligands
*
[l] L. K . Woo, Chem. Rev. 1993, 93, 1125.
(21 L. K. Woo, J. G. Goll, D. J. Czapla, J. A. Hays, J Am. Chem. Sot. 1991, 113,
8478.
131 C. E. Laplaza, A. R. Johnson, C. C. Cummins, J Am. Chem. Soc. 1996, 118,
709.
[4] C. E. Laplaza, A. L. Odom, W. M. Davis, C. C. Cummins, J. D. Protasiewicz,
J. Am. Chem. Soc. 1995, 117,4999.
[5] C. E. Laplaza, C. C. Cummins, Science 1995, 268, 861.
[6] C E. Laplaza, W. M. Davis, C. C. Cummins, Angeiv. Chem. 1995, 107, 2181;
Angew. Chem. In!. Ed Engl. 1995, 34, 2042.
[7] C. E. Laplaza, M. J. A. Johnson, J. C. Peters, A. L. Odom, E. Kim, C. C.
Cummins, G. N. George, I. J Pickering, J Am Chem. SOC.1996, 118, 8623.
IS] D. M.-T. Chan, M. H. Chisholm, K. Folting, J. C. Huffman, N. S. Marchant,
Inorg. Chem. 1986, 25,4170.
191 M. H. Chisholm, F. A. Cotton, C. A. Murillo, W. W Reichert, Inorg. Chem.
1977. 16, 1801.
[lo] F. A. Cotton. R. A. Walton, Multiple Bonds Between Metal Atoms, Oxford
University Press, New York, 1993.
11I ] X-ray crystal structure of 7. A batch of crystals grown from ether was coated
with Paratone-N oil (Exxon). A black parallelepiped of approximate dimensions 0.40 x 0.40 x 0.12 mm was selected. Crystal data: a =16.0996(10),
c = 13.5646(9)A, V = 30449(3) A', 2 = 3, space group R3, p =0.664 mm-',
pcxbd= 1.369 gcrn-,, F(OO0) = 1299. Data collection was carried out on a
Siemens Platform goniometer with a CCD detector at 188(2) K using Mo,.
radiation (L = 0.71073 A). 4238 reflections were collected over the range
- 1 7 S h 2 1 6 , - 1 7 2 k 5 1 7 , and - 8 5 1 2 1 5 , of which 1604 were unique
(&, = 0.1218). The extinction coefficient was 0.0029(6). The structure was
solved by direct methods in conjunction with standard difference Fourier techniques. Least squares refinement based upon F 2converged with residuals of
R, = 0.0692 and wR2 = 0.1741, and GOF =1.210 based upon I>2o(I). The
dimethylamido substituent has a rotational disorder. Occupancy refinement
gave values close to 0.67 and 0.33 for the nitrogen trigonal planeapproximately
parallel and perpendicular to the crystallographic threefold axis, respectively.
For final refinement the occupancies were set to these values. All non-hydrogen
atoms with the exception of those involved in the disorder (C21, C22, C23, and
C24) were refined anisotropically and hydrogen atoms were placed in calculated (d(C-H) = 0.96 A) positions. The largest peak and hole in the final difference map were 0.992 and - 0 . 9 6 6 e k 3 , respectively [28].
[12] F. Weller, W. Liebelt, K. Dehnicke, 2. Anorg ANg. Chem. 1982, 484, 124.
1131 T. Godemeyer, F. Weller, K. Dehnicke, D. Fenske, 2. Anorg. Alg. Chem. 1987,
554, 92.
[14] A. R. Johnson, P. W. Wanandi, C. C. Cummins, W. M. Davis, Organomeralks
1994, 13, 2907.
[15] C. E. Laplaza, W. M. Davis. C. C. Cummins, Organomerullics 1995, 14,
577.
[16] M. H. Chisholm, W. Reichert, J Am. Chem Soc. 1974, 96, 1249.
1171 M. H. Chisholm, F. A. Cotton, B. A. Frenz, W. W. Reichert, L W. Shive, B. R.
Stults, J. Am. Chem. SOC.1976, 98,4469.
[18] M. H. Chisholm, D. A. Haitko, C. A Murillo, Inorg. Synrh. 1982, 21, 51.
[19] X-ray crystal structure of a co-crystal of 13 and 14. A batch of crystals
grown from ether was coated with Paratone-N oil (Exxon). A black parallelepiped of approximate dimensions 0.44 x 0.35 x 0.18 mm was selected Crystal data. u = 8.4348(6), b = 8.4876(6), c =14.9795(11) A, a =102.791(2),
p = 92.055(2), 7 = 97.331(2)", V =1034.96(13) A3, 2 = 2, space group Pi,
p = 1.215 mm-',p,,,,, =1.487 gcm-',F(000) = 475. Datacollection wascarried out on a Siemens Platform goniometer with a CCD detector at 149(2)K
using Mo,, radiation ( 2 = 0.71073 A). 4271 reflections were collected over the
range - 9 2 h 1 9 , - 9 1 k 2 9 , and - 9 5 1 2 1 6 , of which 2922 were unique
(R,,, = 0.0471). Corrections applied: Lorentz-polarization and absorption
and Tm,"were 0.1980 and 0.1469, respectively). The struc(semiempirical, TmaX
ture was solved by direct methods in conjunction with standard difference
Fourier techniques. Least squares refinement based upon F2 converged with
residuals of R, = 0.0671, wR2 = 0.1419, and GOF =1.238 based upon
I > 2a(I). All non-hydrogen atoms were refined anisotropically and hydrogen
atoms were placed in calculated (d(C-H) = 0.96 A) positions. The largest peak
and hole in the final difference map were 2.286 and -0.934 e k ' , respectively
[281
[20] N. Zanetti, R. R. Schrock, W. M. Davis, Angew. Chem. 1995, 107, 2184;
Angeu,. Chem. Inf. Ed. Engl. 1995, 34, 2044.
1211 M. Scheer, Angew. Chem. 1995, 107,2151; Angeiv. Chem. Int. Ed. Engl. 1995,
34, 1997.
[22] M. C. Fermin, J. Ho, D. W. Stephan, J Am. Chem. Soc. 1994, 116,6033.
[23] Crystal structure of 17. A batch of crystals grown from ether was coated with
Paratone-N oil (Exxon). A black parallelepiped of approximate dimensions
0.40 x 0.25 x 0.20 mm was selected. Crystal data: u = 15.5200(9), b =
lO.S063(6), c=19.0840(11)& fi =103.2180(10)", V = 3029.4(3)A3, Z = 2,
space group P2,/c, p = 0.480 mm-', psSlcd= 1.219 gem-,, F(OO0) =1170.
$ 15.00+ .2SjO
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Angew. Chem. Inr. Ed. Engl. 1997,176, No. 112
COMMUNICATIONS
Data collection was carried out on a Siemens Platform goniometer with a C C D
detector at 205(2) K using Mo,, radiation (i
= 0.71073 A). 11621 reflections
were collected over the range - 17 I h 5 15, - 11 I k I l l , and - 21 5 1 1 2 0 , of
which 4331 were unique (R,,, = 0.0434). Corrections applied: Lorentz-polarization, extinction (0.0045(12)), and absorption (semiempirical, 7& and T,,,
were 0 1766 and 0.1342, respectively). The structure was solved by direct methods i n conjunction with standard difference Fourier techniques. Least squares
refinement based upon F z converged with residuals of R , = 0.0756,
wR, = 0.2121. and GOF ~ 1 . 1 7 7based upon 1>2o(I). All non-hydrogen
atoms were refined anisotropically and hydrogen atoms were placed in calculated (d(C--H) = 0.96 A) positions. The largest peak and hole in the difference
map were 3.079 and - 0 . 4 3 7 e k 3 , respectively [28].
1241 J. R. Dilworth, J. Zubieta. Inorg. Synth. 1986, 24, 193.
[25] R. Poli. H. D. Mui, J Am Chem. Soc 1990, f f 2 ,2446.
[26] P Hofacker. C Friebel, K. Dehnicke, P. Bauml, W. Hiller, J. Strahle, Z .
Nulurfi)rsch. B 1989, 44, 1161.
[27] I. Ugi, H. Perlinger, L. Behringer, Chem. Ber. 1958, P i , 2330.
[28] Further details of the crystal structure investigations may be obtained from the
Fachinformationszentrum Karlsruhe, D-76344 Eggenstein-Leopoldshafen
(Germdny). on quoting the depository number CSD-405951 (17), CSD-405952
(7) and CSD-409593 (13/14 cocrystal).
Insertion of Functional Groups into
Square-Planar Units:
A New Construction Principle for
Open Microporous Framework Structures
Michael Schindler* and Werner H. Baur*
Currently 98 different topologies of microporous frameworks
are known,"] most of which are based on variously bridged
coordination tetrahedra of oxygen atoms around aluminum,
phosphorus, and silicon centers. Much current synthetic work
involving related phases is devoted to incorporating reactive
transition metals into these frameworks and to devising compounds with larger pores accessible to larger molecules. The aim
of this work is to increase the potential usefulness of such microporous compounds for catalytic applications.
Recently three phases were synthesized that combine the presence of a reactive transition metal with an accessible pore space;
these phases are thermally reasonably stable, re- and dehydrate
reversibly, and are capable of exchanging cations located in the
pore space: Frankfurt vanadium phosphate one (FVP-1) 1['1
(with 2 . 8 1 ~ 1 4 . 0 -0.1
,
< w , < l . l , 0 5 ~ 5 0 . 2 01y<2.1,
,
and
7 1 2 1 10) as well as compounds 213]and 3.[31At first sight the
1 ,)O,}(PO,),I.(PO,);(OH);zH,O
Na,[{(V:I,V:
1
lHN(CHzCH,)3NHlKi,3,1V,0,(P04),I~~H,0
2
CS,[V,O,(PO,),]. IH,O
3
architecture of these compounds seems to be based on different
principles from those applicable to zeolite frameworks. However, on closer inspection it appears that different chemical compositions require an extension of these principles.
The exciting chemistry and topology of the bonding arrangements in vanadates and related materials has merited two recent
reviews.l4]While many of these phases are based on the principle
of heteropolyions of the Keggin type,"] (i.e. these clusters do
not form strong bonds outside the molecule) the units of 1-3
~
[*] M. Schindler, Prof. Dr. W. H. Baur
Institut fur Kristallographie und Mineralogie der Universitdt
Senckenberganlage 30, D-60054 Frankfurt am Main (Germany)
Fax: Int. code +(69)798 22101
e-mail . Baur(u kristall.uni-frankfurt.d4OO.de
AnRew. Chem. Inr. Ed. Engl. 1997, 36, No. 112
G
are what we denote as anti-Keggin groups (composition
[(V~f,V~~,)O,](PO,),, with -0.1 s w s l.l),~'l in which the
phosphate tetrahedra are outside of the shells of vanadium coordination polyhedra and are, therefore, able to form bridges between neighboring groups. Each of these V,O,(PO,),
(or
V,P,O, 7) groups is composed of five square-pyramidally O-coordinated V atoms and four PO, groups (Figure 1). The central
Figure I . Two bridged spiked helmet V,O,(PO,), units (top) iis well as two joined
square-planar building blocks (bottom), which could, for example, represent two
single four-rings (S4R) or two square-planar coordination polyhedra of 0 around
Nb. The circles denote the connectors to neighboring groups. An individual
V,O,(PO,), group consists of four connectors, in this case phosphate tetrahedra,
and a central square-pyramidal coordination around V 5 + , which shares all its basal
edges with the surrounding square-pyramidal coordination polyhedron around
V 4 + . The symmetry of one spiked helmet V,O,(PO,), unit is 4mm.
vanadyl oxygen atom is bonded to a V5+ ion, its position on the
hemispherical-shaped group is reminiscent of the spike on a
spiked helmet.['' However, in a topological sense the vanadium
coordination polyhedra are only decoration. The active parts of
the group are the phosphate tetrahedra that connect the planar
square groups at their corners after twists of about 90" (Figure 1). Thus, we must initially consider nets composed of
square-planar groupings.
As far as we know, nets of bonds have not been studied from
this viewpoint. However, studies by Wells[61and Smith"] include useful information on this topic. We consider our basic
building units to be four-connected square-planar groups,
which can differ considerably in terms of their chemistry and
size. Thus, the planar four-coordinations of oxygen atoms
around Nb (and Nb around 0) yield in one topology the NbO
crystal structure typers1 (Figure 2a and Table I ) , and single
four-rings (S4R) of silicate tetrahedra Si,O,O,,, yield within the
NbO framework the crystal structure of the zeolite sodalite[']
(Figure 2b and Table 1). By connecting the squares we can obtain either the framework of 1 (and 3) with the spiked helmet
unit as the building block (Figure 2c, Table 1) or the framework
of 4"01 (not illustrated) with the square-planar Mo,O,(PO,),
group as the building block. The central part of this group
consists of a Mo,O:+ cube with four molybdenyl (Mo=O)
groups and two Mo-Mo bonds; that is, it is chemically completely different from the vanadium phosphate groups in 1 and
3 but the connectivity properties of both groups are identical.
Thus, we know four frameworks, which are constructed by con-
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