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Aminolysis reactions of tungsten hexafluoride N-alkylimidofluorotungstates(VI)
1NORG. NUCL. CHEM. LETI'ERS. Vol. 12, pp.559 - 561, 1976. Pergaom Press. Printed in Great Britain.
~ I N O L Y S I S REACTIONS OF TUNGSTEN HEXAFLUORIDE N-ALKYLIMIDOFLUOROTUNGSTATES(VI) O.R. Chambers, D.S. Rycroft, D.W.A. Sharp~ and J.M. Winfield, Chemistry Department, University of Glasgow, Glasgow G12 8QQ, Scotland (Received 5 April 1976)
The ability of tungsten hexafluoride to behave as a Lewis acid is well documented (],2), and the resulting complexes are formulated from their n.m.r, qpectra as molecular species (2). An adduct, WF6.3MeNH2, has been described (I), but we now show that WF 6 undergoes aminolysis with primary amines RNH 2 (R = Me, Et, Bu~, and Bu ~) and with methyl(trimethylsilyl)amine to give products containing R-N-W VI groups.
The behaviour of
BuNH 2 and hexamethyldisilazane towards WF 6 has been reported recently, but details are not available (3). Hethylamine
(5-2mmol') reacts with tungsten hexafluoride
(12-4mmoi) in vacuo below room temperature according to t 2MeNH 2 ~ MeNH3+WFsNMe+ HF WF 6 The white, solid product is characterised from its analysis (Table I) and its IH and 19F n.m.r, spectra (Table 2) as methylammonium N-methylimidopentafluorotungsta%e(VI).
N.m.r.
signals due to the cation and the anion are readily identified. The anion has a pseudo-octahedral structure similar to that suggested for the compound WF4(NMe)-NCMe (4), and the C-N-W group is assumed to be linear with substantial multiple bonding between nitrogen and tungsten. visible in the 19F spectrum;
14N-19F Coupling is clearly the signal due to F t (tra~s to -NMe)
comprises a 1:1;] triplet of overlapping quintets.
Relative
signs of the coupling constants (Table 2) were determined from 1 9 F - ~ g F ~ and 1 9 F - ~ 4 N ~ double resonance experiments which also yield 5(N) = -1.2 p.p.m. (w.r.t. NO 5 ) and 2j(FcN) ~ I Hz. The N-CH 3 signal is broad due to IH-]4N and ]H-]9F coupling, and although precise values could not be obtained, decoupling experiments enabled satellites due to 3j(HW) = 10 Hz to be observed. 5~
560
Aminolysis Reactions
TABLE I Compound t
MeNH 3 W F 5 ~ e EtNH3+WF5NMeWF6-3Bu!NH 2
C H 6-9(7.1) 2.5(2.7) 13.1(13-0) 4.0(3-5) 27-8(27.9) 6-3(6-4)
Found ( r e q u i r e d ) F N 28.1 (27-9) 8-0(8.2) 25-7(25.8) 7.7(7-6) 22-3(22.1) 8.2(8-1)
W 54-4(54-1) 49.8(50-0) 35-5(35.6)
TABLE 2 WF5NMe5(F c) 6(F t) 8(H) 2j(FcF t) 1j(FcW) Ij(FtW) 2J(FtN)
28.0 -101-5 5.52 ~60 Z47 ~36 +_40
W2F9(NMe)235-7 -127-4 4-80 60, 4 j ( F c F c ' ) 47
= ~I
34
The compound EtNH3+WF5NEt - is formed from EtNH 2 and WF 6 (Table I), Fine structure due to 14N coupling is absent in its 19F n.m,r, spectrum~ and also in the spectrum of the ~-butyl analogue, but the broad quintets observed for F t sharpen on decoupling 14N. Evidently the electric field gradient at 14N in WF5NR- compounds increases with increasing size of R. Under similar conditions WF 6 and tert-butylamine give a 1:3 adduct which is characterised from its spectra and analysis (Table I) as a 1:1 mixture of Bu!NH3+WF5NBu l- and Bu~NH3+F -. Chemical s h i f t s (8 p . p . m . ) w . r . t , i n t e r n a l CCI~F and MeASi a r e positive to low field, Coupling constants (H~). F c ~nd F t cis and trans respectively to -NMe. With m e t h y l ( t r i m e t h y l s i l y l ) a m i n e both a m i n o l y s i s and c l e a v a g e o f t h e Si-N bond o c c u r . The p r o d u c t s a r e t r i m e t h y l s i l y l f l u o r i d e and bleNH3+ s a l t s o f WF.NMe-) and ~ - f l u o r o b i s [N-methylimidotetrafluorotungstate(VI)J, [F4(MeN)WF%~(NMe)F4J-. The l a t t e r a n i o n i s i d e n t i f i e d from i t s n . m . r , s p e c t r a (Table 2 ) , and has a b i - o c t a h e d r a l s t r u c t u r e w i t h a l i n e a r , or n e a r - l i n e a r ,
Aminolysis Reactions
C-N-W-F-W-N-C skeleton. The bridging F-ligand (F t) is coupled to eight equivalent 19F and two equivalent 14N nuclei. Thirtyfive lines of the expected forty-five line spectrum are observed, and the a~reement between calculated and observed spectra is excellent. This work has shown that there is a close relationship between alkylimido- and oxo-ligands. The anions described here are analogous to WOF 5- and W202F9- . They show similar relationships in their n.m°r, spectra (5), for example 1J(FcW) and Ij(FtW ) in WFsX- (X = 0 or NMe) are of opposite sio~n. AeknowledKemen% We thank the S.R.C for support.
I. 2.
H.C. F.N. A.M. 339
References CLARK and H.T. EMELEUS, J.Chem.Soc., 4778 (1957) TEBBE and E.L. MUETTERTIES, Inorg.Chem., 7, 172 (1968); NOBLE and J.M. WINFIELD, Inorg.Nucl.Chem.Letters, 4 (1968); A. STEIGEL and S. BROWNSTEIN, J.Amer.Chem.Soc.
4.
96, 6227 (1974). Yu. V. KOKUNO¥, Yu. D. CHUBAR, V.A. BOCHKAREVA, and Yu. A. BUSLAEV, Koord. Khim., I, 1100, (1975). M. HARMAN, D.W.A. SHARP, and J.M. WINFIELD, Inorg. Nucl.
5.
Chem. Letters, 10, 183 (1974} W. McFARLANE, A.M. NOBLE, and J.M. WINFIELD, J.Chem.Soc.(A),
3.
948 (1971)
561
~ I N O L Y S I S REACTIONS OF TUNGSTEN HEXAFLUORIDE N-ALKYLIMIDOFLUOROTUNGSTATES(VI) O.R. Chambers, D.S. Rycroft, D.W.A. Sharp~ and J.M. Winfield, Chemistry Department, University of Glasgow, Glasgow G12 8QQ, Scotland (Received 5 April 1976)
The ability of tungsten hexafluoride to behave as a Lewis acid is well documented (],2), and the resulting complexes are formulated from their n.m.r, qpectra as molecular species (2). An adduct, WF6.3MeNH2, has been described (I), but we now show that WF 6 undergoes aminolysis with primary amines RNH 2 (R = Me, Et, Bu~, and Bu ~) and with methyl(trimethylsilyl)amine to give products containing R-N-W VI groups.
The behaviour of
BuNH 2 and hexamethyldisilazane towards WF 6 has been reported recently, but details are not available (3). Hethylamine
(5-2mmol') reacts with tungsten hexafluoride
(12-4mmoi) in vacuo below room temperature according to t 2MeNH 2 ~ MeNH3+WFsNMe+ HF WF 6 The white, solid product is characterised from its analysis (Table I) and its IH and 19F n.m.r, spectra (Table 2) as methylammonium N-methylimidopentafluorotungsta%e(VI).
N.m.r.
signals due to the cation and the anion are readily identified. The anion has a pseudo-octahedral structure similar to that suggested for the compound WF4(NMe)-NCMe (4), and the C-N-W group is assumed to be linear with substantial multiple bonding between nitrogen and tungsten. visible in the 19F spectrum;
14N-19F Coupling is clearly the signal due to F t (tra~s to -NMe)
comprises a 1:1;] triplet of overlapping quintets.
Relative
signs of the coupling constants (Table 2) were determined from 1 9 F - ~ g F ~ and 1 9 F - ~ 4 N ~ double resonance experiments which also yield 5(N) = -1.2 p.p.m. (w.r.t. NO 5 ) and 2j(FcN) ~ I Hz. The N-CH 3 signal is broad due to IH-]4N and ]H-]9F coupling, and although precise values could not be obtained, decoupling experiments enabled satellites due to 3j(HW) = 10 Hz to be observed. 5~
560
Aminolysis Reactions
TABLE I Compound t
MeNH 3 W F 5 ~ e EtNH3+WF5NMeWF6-3Bu!NH 2
C H 6-9(7.1) 2.5(2.7) 13.1(13-0) 4.0(3-5) 27-8(27.9) 6-3(6-4)
Found ( r e q u i r e d ) F N 28.1 (27-9) 8-0(8.2) 25-7(25.8) 7.7(7-6) 22-3(22.1) 8.2(8-1)
W 54-4(54-1) 49.8(50-0) 35-5(35.6)
TABLE 2 WF5NMe5(F c) 6(F t) 8(H) 2j(FcF t) 1j(FcW) Ij(FtW) 2J(FtN)
28.0 -101-5 5.52 ~60 Z47 ~36 +_40
W2F9(NMe)235-7 -127-4 4-80 60, 4 j ( F c F c ' ) 47
= ~I
34
The compound EtNH3+WF5NEt - is formed from EtNH 2 and WF 6 (Table I), Fine structure due to 14N coupling is absent in its 19F n.m,r, spectrum~ and also in the spectrum of the ~-butyl analogue, but the broad quintets observed for F t sharpen on decoupling 14N. Evidently the electric field gradient at 14N in WF5NR- compounds increases with increasing size of R. Under similar conditions WF 6 and tert-butylamine give a 1:3 adduct which is characterised from its spectra and analysis (Table I) as a 1:1 mixture of Bu!NH3+WF5NBu l- and Bu~NH3+F -. Chemical s h i f t s (8 p . p . m . ) w . r . t , i n t e r n a l CCI~F and MeASi a r e positive to low field, Coupling constants (H~). F c ~nd F t cis and trans respectively to -NMe. With m e t h y l ( t r i m e t h y l s i l y l ) a m i n e both a m i n o l y s i s and c l e a v a g e o f t h e Si-N bond o c c u r . The p r o d u c t s a r e t r i m e t h y l s i l y l f l u o r i d e and bleNH3+ s a l t s o f WF.NMe-) and ~ - f l u o r o b i s [N-methylimidotetrafluorotungstate(VI)J, [F4(MeN)WF%~(NMe)F4J-. The l a t t e r a n i o n i s i d e n t i f i e d from i t s n . m . r , s p e c t r a (Table 2 ) , and has a b i - o c t a h e d r a l s t r u c t u r e w i t h a l i n e a r , or n e a r - l i n e a r ,
Aminolysis Reactions
C-N-W-F-W-N-C skeleton. The bridging F-ligand (F t) is coupled to eight equivalent 19F and two equivalent 14N nuclei. Thirtyfive lines of the expected forty-five line spectrum are observed, and the a~reement between calculated and observed spectra is excellent. This work has shown that there is a close relationship between alkylimido- and oxo-ligands. The anions described here are analogous to WOF 5- and W202F9- . They show similar relationships in their n.m°r, spectra (5), for example 1J(FcW) and Ij(FtW ) in WFsX- (X = 0 or NMe) are of opposite sio~n. AeknowledKemen% We thank the S.R.C for support.
I. 2.
H.C. F.N. A.M. 339
References CLARK and H.T. EMELEUS, J.Chem.Soc., 4778 (1957) TEBBE and E.L. MUETTERTIES, Inorg.Chem., 7, 172 (1968); NOBLE and J.M. WINFIELD, Inorg.Nucl.Chem.Letters, 4 (1968); A. STEIGEL and S. BROWNSTEIN, J.Amer.Chem.Soc.
4.
96, 6227 (1974). Yu. V. KOKUNO¥, Yu. D. CHUBAR, V.A. BOCHKAREVA, and Yu. A. BUSLAEV, Koord. Khim., I, 1100, (1975). M. HARMAN, D.W.A. SHARP, and J.M. WINFIELD, Inorg. Nucl.
5.
Chem. Letters, 10, 183 (1974} W. McFARLANE, A.M. NOBLE, and J.M. WINFIELD, J.Chem.Soc.(A),
3.
948 (1971)
561