The Butterfly Dimer [(tBu3SiO)Cr]2 (μ-OSitBu3)2 and Its Oxidative Cleavage to (tBu3SiO)2 Cr(=N-N=CPh2)2 and (tBu3SiO)2 Cr=N(2,6-Ph2-C6H3) Page: 2,019
This article is part of the collection entitled: UNT Scholarly Works and was provided to UNT Digital Library by the UNT College of Arts and Sciences.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
[(Bu3SiO)Cr](p -OSBu3)2 and Its Oxidative Cleavage
PC. Elemental analyses were performed by Oneida Research
Services, Whitesboro, NY, or Robertson Microlit Laboratories,
Madison, NJ. Magnetic moments were determined in C6D6 at room
temperature using Evans' method16 with an applied diamagnetic
correction.
Procedures. 1. [(tBu3SiO)Cr]2(,p-OSitBu3)2 (12). A 50 mL flask
was charged with CrCl2(thf) (0.600 g, 3.077 mmol), NaOSitBu3
(1.070 g, 4.487 mmol), and thf (40 mL). The mixture was stirred
at 23 C for 10 h, and the solvent was removed under vacuum.
The green solid was heated at 70 OC under vacuum to effect
desolvation, extracted with pentane, and filtered. The solution was
concentrated and crystallized at -78 C to yield 12 as green blocks
(0.806 g, 74% based on NaOSitBu3). 1H NMR (C6D6, 400 MHz):
6 1.71 (vl/2 210 Hz). IR (Nujol Mull, NaC1, cm-1): 1012 (w),
952 (m), 922 (s), 858 (m), 820 (s), 621 (s). Anal. Calcd C24H54-
Si202Cr: C, 59.68; H, 11.29. Found: C 56.8, H 11.2. Yeff(293 K)
= 2.8 uB (Evans' method in C6D6).
2. trans-(tBu3SiO)2Cr(p-NCC6H4Me)2 (1-(NCtol)2). p-NCC6H4-
Me (0.049 g, 0.418 mmol) was added to a pentane solution of 12
(0.100 g, 0.104 mmol). Yellow crystalline 1-(NCtol)2 precipitated
over 20 min (0.138 g, 93%). 1H NMR (C6D6, 400 MHz): 6 -13.04
(v1/2 m 470 Hz, 4H, CH), 3.35 (v1/2 800 Hz, 54H, silox), 16.11
(v1/2 100 Hz, 4H, CH), 20.97 (v1/2 m 110 Hz, 6H, Me). IR (Nujol
Mull, NaC1, cm-1): 2258 (s), 1606 (s), 1509 (m), 1178 (m), 997
(br s), 933 (w), 816 (s), 614 (s), 552 (s). Anal. Calcd C40H68Si2N202-
Cr: C, 64.6; H, 10.3; N, 4.2. Found: C, 61.8; H, 9.4; N, 5.5. ,teff-
(293 K) = 4.8 YpB (Evans' method in C6D6).
3. trans-(tBu3SiO)2Cr(NCtBu)2 (1-(NCtBu)2). tBuCN (9 pyL, 0.08
mmol) was added to a C6D6 solution containing 12 (0.020 g, 0.0207
mmol). The solution turned pink instantaneously. Slow evaporation
of the C6D6 solution yielded pink solid 1-(NCtBu)2 (~0.015 g,
~60%). 1H NMR (C6D6, 400 MHz): 6 3.04 (v1/2 670 Hz, 54H,
C(CH3)3), 5.73 (v1/2 230 Hz, 18H, NCtBu). IR (Nujol Mull, NaC1,
cm-1): 2272 (s), 1239 (m), 1207 (w), 1027 (s), 986 (s), 932 (m),
817 (m), 614 (s), 583 (m).
4. trans-(tBu3SiO)2Cr(CNtBu)2 (1-(CNtBu)2). A 3 dram vial was
charged with 12 (0.101 g, 0.105 mmol), CNtBu (47 pyL, 0.449
mmol), and pentane (3 mL). The solution was allowed to sit 16 h,
and then the solvent was allowed to slowly evaporate at 230C to
yield orange microcrystalline 1-(CNtBu)2 (0.113 g, 83%). 1H NMR
(C6D6, 300 MHz): 6 3.17 (peak has an upfield shoulder, v1/2
700 Hz). IR (Nujol Mull, NaC1, cm-1): 2192 (s), 2099 (m), 1237
(m), 1206 (s), 1024 (s), 977 (s), 851 (w), 817 (s), 707 (w), 615 (s).
,Ueff(293 K) = 4.8,uB (Evans' method in C6D6).
5. (tBu3SiO)2Cr(PMe3)2 (1-(PMe3)2). An NMR tube was charged
with 12 (0.025 g, 0.0518 mmol) and PMe3 (0.5 mL), forming a
deep blue solution. The PMe3 was removed under vacuum to yield
a tacky blue solid. Attempts at scaling up the reaction resulted in
deep blue oils. 1H NMR (C6D6, 400 MHz): 6 1.23 (vl/2 680 Hz,
54H, C(CH3)3), 17.79 (v1/2 900 Hz, 18H, PMe3).
6. trans-(tBu3SiO)2Cr(O=CPh2)2 (1-(OCPh2)2). A 3 dram vial
was charged with 12 (0.080 g, 0.083 mmol), benzophenone (0.060
g, 0.329 mmol), and heptane (2 mL). The solution was allowed to
sit 16 h, and then the solvent was allowed to slowly evaporate at
23 oC to yield purple-red microcrystalline 1-(OCPh2)2 (0.092 g,
66%). 1H NMR (C6D6, 400 MHz): 6 1.72, 3.21 (resonances
overlap). IR (Nujol Mull, NaC1, cm-1): 1625 (s), 1598 (s), 1574
(s), 1329 (s), 1298 (s), 1285 (s), 1182 (m), 1160 (m), 989 (s), 948
(m), 940 (m), 928 (m), 819 (s), 766 (s), 709 (s), 696 (s), 643 (s),616 (s). Anal. Calcd C50H74Si204Cr: C, 70.9; H, 8.8. Found: C,
69.2; H, 9.0. Yeff(293 K) = 4.8 puB (Evans' method in C6D6).
7. 2. (tBu3SiO)2Cr(N2CPh2)2 (2). A 4 dram vial was charged
with 12 (0.127 g, 0.132 mmol) and pentane (3 mL). Ph2CN2 (0.102g, 0.525 mmol) was added to the green solution which instantly
turned dark brown. The solution was allowed to slowly evaporate
at -30 C, yielding black crystals (0.129 g, 56%). 1H NMR (C6D6,
400 MHz): 6 1.26 (s, 54H, C(CH3)3), 6.9-7.1 (m, 12H, CHmeta,-
CHpara), 7.69 (d, 3J = 5, 4H, CHortho). 13C{1H} NMR (C6D6, 400
MHz): 6 24.73, 30.89, 128.99, 131.10, 136.01, 149.95. IR (Nujol
Mull, NaC1, cm-1): 1587 (s), 1565 (s), 1321 (s), 1178 (m), 1077
(m), 1027 (m), 1000 (m), 983 (m), 956 (s), 933 (s), 909 (s), 818
(s), 775 (s), 765 (s), 693 (s), 655 (m), 622 (m), 570 (m). Anal.
Calcd C50H74Si2N402Cr: C, 68.9; H, 8.6; N, 6.4. Found: C, 68.8;
H, 9.2; N, 4.8.
8. (tBu3SiO)2Cr=NAd (3-Ad). A 4 dram vial was charged with
12 (0.080 g, 0.083 mmol), AdN3 (0.029 g, 0.164 mmol), and pentane
(3 mL). The solution was allowed to sit 12 h, and then the solvent
was allowed to slowly evaporate at -30 OF to yield red microc-
rystalline 3-Ad (0.071 g, 68%). 1H NMR (C6D6, 400 MHz): 6
-12.71 (v1/2 380 Hz, 6H, CH2), 2.05 (v1/2 450 Hz, 54H,
C(CH3)3), 4.28 (v1/2 100 Hz, 6H, CH2). IR (Nujol Mull, NaC1,
cm-1): 1306 (s), 1174 (m), 1150 (s), 1098 (s), 1084 (m), 1061 (s),
1027 (s), 986 (s), 944 (s), 901 (s), 858 (s), 816 (s), 709 (m), 672
(m), 619 (s). Anal. Calcd C34H69Si2NO2Cr: C, 64.6; H, 11.0; N,
2.2. Found: C, 64.2; H, 11.8; N, 2.8.
9. (silox)2Cr=N(2,6-Ph2C6H3) (3-(2,6-Ph2-C6H3)). A 50 mL
flask equipped with a stir bar was charged with 12 (714 mg, 0.737
mmol), N3(2,6-Ph2)C6H3 (400 mg, 1.47 mmol), and 15 mL of
pentane. Upon warming to 23 C, the reaction mixture bubbled
vigorously and turned reddish-brown. After the solution was stirred
for 10 h at 23 C, the volatile materials were removed, resulting in
932 mg of a red-brown 3-(2,6-Ph2-C6H3) (87%). 1H NMR (C6D6,
400 MHz): 6 -64.92 (v1/2 m 90 Hz, 2H), -0.15 (v1/2 40 Hz,
4H), 3.04 (v1/2 140 Hz, 54H, C(CH3)3), 14.06 (v1/2 m 20 Hz,
2H), 25.46 (v1/2 210 Hz, 4H), 83.54 (vl/2 80 Hz, 1H). IR
(Nujol Mull, NaC1, cm-1): 1500, 1295, 1116, 1096, 1067, 983,
817, 758, 698, 619. Anal. Calcd CrSi202NC42H67: C, 69.5; H, 9.3;
N, 1.9. Found: C, 69.0; H, 9.6; N, 2.2. ,eff(293 K) = 2.8 ,B (Evans'
method in C6D6).
10. (silox)2Cr=N(2,6-Pr2-C6H3) (3-(2,6-'Pr2-C6H3)). To sepa-
rate 50 mL flasks on opposite ends of a double-ended frit fitted
with a 90 needle valve was added 12 (680 mg, 0.702 mmol) and
N3(2,6-iPr2-C6H3) (285 mg, 1.40 mmol). Into the flask containing
the azide was distilled 20 mL of pentane; the orange solution was
then filtered to the flask containing 12. Upon being mixed,
effervescense and a color change to brown were noted. The solution
was stirred for 10 h at 23 C, and the volatile materials were
removed, resulting in 758 mg of a dark brown 3-(2,6-iPr2-C6H3)
(82% yield). 1H NMR (C6D6, 500 MHz): 6 -62.80 (vl/2 m 135
Hz, 2H), -27.90 (vl/2 550 Hz, 1H), 0.60 (v1/2 160 Hz, 12H,
CH(CH3)2), 3.56 (v1/2 v 200 Hz, 54H, C(CH3)3), 93.40 (vl/2
200 Hz, 2H) IR (Nujol Mull, NaC1, cm-1): 1587, 1275, 1103, 1043,
817, 745, 618. Anal. Calcd CrSi202NC36H71: C, 65.7; H, 10.9; N,
2.1. Found: C, 65.5; H, 10.6; N, 2.4. eff(293 K) = 2.7 B (Evans'
method in C6D6).
11. (silox)2Cr=N(2,4,6-Me3C6H2) (3-Mes). To separate 50 mL
flasks on opposite ends of a double-ended frit fitted with a 900
needle valve were added 600 mg (0.619 mmol) of [Cr2] and 200
mg (1.24 mmol) of N3C6H3-(CH3)3-2,4,6. Into the flask containing
the azide was distilled 20 mL of pentane; the orange solution was
then filtered to the flask containing the [Cr2]. Upon mixing,
effervescense and a color change to red-brown were noted. The
solution was stirred for 10 h at 25 oC, the volatile materials werestripped, resulting in 688 mg of a dark brown solid (90% yield).
1H NMR (C6D6, 500 MHz): 6 -93.46 (v1/2 m 330 Hz, 3H), -68.00
(v1/2 200 Hz, 2H), -55.61 (v1/2 - 605 Hz, 6H), 3.74 (v1/2Inorganic Chemistry, Vol. 45, No. 5, 2006 2019
Upcoming Pages
Here’s what’s next.
Search Inside
This article can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Article.
Sydora, Orson L.; Kuiper, David S.; Wolczanski, Peter T.; Lobkovsky, Emil B.; Dinescu, Adriana & Cundari, Thomas R., 1964-. The Butterfly Dimer [(tBu3SiO)Cr]2 (μ-OSitBu3)2 and Its Oxidative Cleavage to (tBu3SiO)2 Cr(=N-N=CPh2)2 and (tBu3SiO)2 Cr=N(2,6-Ph2-C6H3), article, January 12, 2006; [Washington, DC]. (https://digital.library.unt.edu/ark:/67531/metadc75425/m1/12/: accessed April 24, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT College of Arts and Sciences.