close

Вход

Забыли?

вход по аккаунту

?

The Bonding Capability of Imido Complex Fragments of Groups 5Ц7 with Regard to the Isolobal Relationship.

код для вставкиСкачать
COMMUNICATIONS
by 50%. Small colorlcss crystals of 3 formed in 18% yield (0.58 g) after storage of
this solution at -20 C for several days. (M.p. 170 C).
Received: January 20, 1994 [Z6636IE]
German version: Angew. Chem. 1994, iU6,1354
The Bonding Capability of Imido Complex
Fragments of Groups 5-7 with Regard to
the Isolobal Relationship**
Jorg Sundermeyer* and Diane Runge
Dedicated to Professor Helmut Werner
Inorgunic Chemistry. Orgunogulliurn Cofnpounfls,Purl 1,
Springer. Berlin. 1987.
on the occasion of his 60th birthday
[2] P. L . Baxter. A. J. Downs. M. J. Goode, D. W. H. Rankin, H. E. Robertson, J.
C'hi~nr.So(. C'hc.in Comn7uri. 1986. 805.
In bond theory organoimido and cyclopentadienyl ligands
[3] M. .I Goode. A. J Downs, C. R. Pulham. D. W. H. Rankin, H. E. Robertson.
show surprising parallels.[21If they are considered as anionic ligJ, Cheri~.Sol Chwr. Con~n~un.
1988, 768.
[4] P. L. Baxter. A. J. Downs. M . J. Goode. D. W. H. Rankin. H. E. Robertson, J
ands, they both make a maximum of six electrons available for
f'hcni SM. Dulton Truns. 1985. 807.
bonding with a metal cation.[31Both are 0.2 x-bonding ligand~,[~I
[5] C. R. Pulham. P. T. Brain. A. J. Downs, D. W. H. Rankin. H. E. Robertson. J.
which form 0 and K bonds with metal orbitals of the same symC h i ~ n iSoi..
.
CIi(~i7.Connirun. 1990, 177.
metry.I5] If the C,R; anion binds to a d"-M metal center (e.g.,
[6] M. T. Barlow. C . J. D a n . A. J. Downs. G. S. Laurensen, D. W. H. Rankin. J.
C ~ P ISfif..
~ I . D d i m Trans. 1982, 597.
do-W6+) and the dianion N R 2 to an isoelectronic d"-M' metal
[7] For interesting polycycles with gallium hydride moieties. see M. J. Henderson,
center
from the following group in the periodic table (e.g., doC. H. Kcnnard. C L Raston, G. Smith. J. C h ~ mSoc.
.
Chew. C~iminun.1990.
Re7+),two entities with the same electron count and comparable
1203: J . L. Atwood. S G. Bolt, C. Jones. C. L. Raston, Inorg. Cliem. 1991,3U.
valence orbitals result (e.g., [W(q5-C5R5)I5+or [Re(NR)]'+).
4868.
[XI R. Kiippe. M. Tdcke, H. Schnockel, Z. Anorg. Allg. Chern. 1991. 605, 3 5 : R.
Schrock et al.[61have already pointed out parallels in the chemKiippe. H. Schncickel, J Chew. Soc. Dalton Trans. 1993, 3393.
istry of complexes with the entity [M(NAr),] (M = Mo, W ;
[9] S. Schulz. S. Pusch, E. Pohl, S. Dielkus. R. Herbst-lrmer, A. Meller. H. W.
Ar = 2,6-iPr2C,H,) and those containing the metallocene unit
Roesky. Inorg. Chen. 1993, 32, 3343; M . A. Petrie, P. P. Power, H. V. Rasika
[Cp,M] ( M = Ti, Zr, Hf; C p = q5-C5H5).Gibson et al. extended
Dias. K. Ruhlandt-Senge. K . M. Waggoner. R. J. Wehmschulte. Organonietul/ic., 1993. 12. 10x6
this relationship to the linking fragments [CpM(NR)] ( M = Nb.
[in] I H N M R ( ~ O O . ~ ~ M H Z . C , D , . ~ ~ ~ K
I :,&T=M1 .S2 )9:( s , i x ~ . o - t ~ u ) , 1 . 3 5
Ta) and confirmed the isolobal character of these three complex
( s . H. /I-rBu). 6.41 (br. 2 H. GaH,), 7.40 ( 5 . 2 H. H-aryl). 2: fi = 1.46 (br. 2
fragments by quantum-mechanical calculations[71and reactivity
H. CH,). 1.70 (s. 6 H. 2 CH,), 6.62 (br. 1 H. GaH); 3.5-fBu,C,H3: 1.23 ( s . 18
studiesr8'(Scheme 1 , top). Recently we reported on M -M' coupH. i i i - / B u ) . 7.40 ( I , 1 H.p-H-aryl, J 1.8 H r J , 7 57 (d. 2 H, o-Hi-aryl,J 1.8 Hz).
Z.4.6-tBu,C,H2. 1 14(s.9H.p-rBu). 1.38(s. 18H,o-tBu).7.42(~.2H.H-aryI)
3: 0 = 1.31 (s.9 H.p-iBu). 1.58(s. 18 H,o-rBu).7.62(~.2H. H-aryl): l R ( K B r ) .
1 -t[cm
,
'1 = 2961 s. 2905 m, 2867 m. 2818 w sh. 1908 ni sh, 1887 s. 1584s. 1540
NR
R
in. 1530 w. 1476 m. 1461 m. 1392 s, 1361 s. 1255 ni, 1217 m. 1202 w. 1190 w,
I
II
I
1145 in. 1106 s br. 992 w sh. 965 m. 811 m. 767 m ; 2: i.[cniC'] = 2Y63 s, 2905
m. 2867 in. 1843 m. 1596 m, 1477 m, 1460 w, 1393 w. 1362 m, 1261 s. 1245 w
sh. 1202 u br, 1099 s; 1023 s. 899 w, 872 m, 802 s. 725 u sh, 714 m br; 3
i,[cm-'] = 2966 5 . 2901 m br. 2875 s. 1786 w, 1769 w. 1596 s. 1539 w. 1486 w
sh. 1462 s. I404 s. 1365 c. 1271 m sh, 1258 s. 1210 m. 1128 m. 1101 s. 1022 m
br. 9-70 w,906 in. 881 s, 811 s. 745 m. MS (CI. CH4): 1 : in;: 315 ( M I - H,
100"%J:HRMS: Calculated forC,,H,,h9Ga 315.1603; found315.1590.2: mlz
55Y (.I4'- H. 100%). 315 ( M + - rBu,C,H,. 47%): HRMS: Calculated for
C,,,HI,""Ga 559.3794:found 559.3778: 3: m i z 6 7 6 ( M - + CI), 605 (M'-CI).
395 (,I4 - - Ar): HRMS: Calculated for C,,,H,,InCI, (.MCI) 675.2954;
found 675.2945. The X-ray crystal structure of 3 has been determined and will
be published elsewhere.
Scheme 1. lsolohal relationships in imido complex fragments.
[I I ] C. Jones, G A. Koutsantonis, C. L. Raston. Pulxhrdron 1993. 12. 1829
[12] Crystalstructuredatafor 1.Cl,H,,Ga,monoclinic,spacegroupP2,~~~~.Z
= 2.
u = 9 9 ? 7 ( 1 ) . h=Y.694(2).c=10.273(1)A, /(=112.58(1), V=912.9(3)A3,
/ J ,",,~ , = l . l 5 g ~ n i ~ ~ . M o , , . i = 0 . 7 1 0 7 3 ~ , ~ i = 1 . 4 8 91711
m m uniquedata
~'.
ling reactions of the two homoleptic imidoyl cations
were collected at 173 K on a Nicolet P 3 diffractometer ( m scan technique.
[Re(NR),]+ and [Mo(NR),]" (R = tBu) with carbonyl meta4.0 < 21) < 50.0 1. Of these. 907 have I > 4 ~ 1 1 and
)
were used for structure
lates [Cp,M(CO),,J of Groups 6-8.19) It was shown that a
solution and refinement. R = 0.095. The oriho tBu groups are disordered. The
direct metal-metal interaction is possible between high- and
site occupation t:dctors for CX and C9 are 69(1)%: those for C14 and C15 are
55(1 J'% The hydrogen atoms on gallium could not be located and were not
low-valent metal centers. These results prompted us to the quesincluded in the refinement: the other hydrogen atoms were calculated in idealtion whether the bonding capability (concept according to R.
Crystal structure data for 2, C,,H,,Ga. monoired positions (C- H 0.96
Hoffmann[""]) of imido complex fragments [Cp,M'(NR),] (M
clinic. space group P Z , ; ~z, = 4. o = 9.355(2). h = 27.930(6). c = 14.110(3) A,
Groups 5, 6, or 7) can be determined along the route of
/ ~ = l ( l 7 . 1 4 ( 3 ) .1 ' = 3 5 2 3 . 0 ( 1 ) ~ ~ , p ~ ~ , ~ , = 1 . 0 5 9 g c m ~ ' , M o , , , i = 0 . 7 1 0 7 3from
~,
/I = 0 X O I mm- I. 4485 unique data were collected on a Siemens R 3m:V difselective M - M' coupling reactions. by binding representative
fractometer at 298K (20-0 scan technique. 3.5 > 211 < 45.0~).Of these. 1567
complex fragments with these entities to the classic 17 valence
had I > 4 u ( 1 ) and were used for structure solution and refinement.
electron unit [CpFe(CO),] . Extrapolation of these studies could
R = 0.0813. Two of the tBu groups are disordered. The site occupation factors
lead to the derivation of a new isolobal relationship between
are71(3)"/0 forC(41),C(42).andC(43): thoseforC(l01).C(104).andC(lOS)
are 47(2l'%. Further details of the crystal structure investigations may be obcarbonyl and imido complex fragments [Cp,M'(NR),,] .
tained from the Fachinformationszentrum Karlsruhe, D-76344 EggensteinAccording to the cyclopentadienyl-imido analogy, not only
Leopoldschafen ( F R G ) . on quoting of depository number CSD-58075.
the homoleptic imido complex fragments [Mo(NtBu),12 and
[13] A. Meller, S Pusch, E. Pohl, L. Himing. R. Herbst-Irmer, Chein. Ber. 1993.
i76.23S.
[*I Dr. J. Sundermeyer, DipLChem. D. Runge
Institut fur Anorganische Chemie der Universitlt
A m Hubland. D-97074 Wurzburg (FRG)
Telefax: Int. code (931)-888-4605
[**I High-valent derivatives ofthe d-metal acids. Part 11. This work was supported
by the Fonds der Chemischen Industrie and the Deutsche Forschungsgemeinschaft (SFB 347). We thank Professor Helmut Werner for his support and the
company H. C. Starck, Goslar. for a gift of high purity grade metal oxides and
chlorides. Part 10: Ref. [I].
[I 1
Gnrt,liii Hunrlhook of
~
-
.
Gv
+
A).
+
+
Angew. C h ~ ~ iInt.
n . E d Dig/. 1994. 33, No. 12
'C VCH
Verlugsge.cellsrhufimbH, 0-69451 Weinhrim, 1994
S 10.00+ .2SW
057U-O833;94:121~-125S
1255
COMMUNICATIONS
[ W ( N ~ B U ) , ] ~can
+ be used as building blocks for the synthesis
of trinuclear complexes [FeJ-[M”]-[Fe] ([Fe] = [CpFe(CO),]).
but also the metal Lewis acids of Group 5 [CpNb(NtBu)]’+ and
[CpTa(NtBu)]’ [ I 1 (Scheme 2). The reactions indicate that
+
2
Fe
complex fragment [CpFe(CO),] has now led to a series of diamagnetic, mixed-valent imido complexes that we were able to
characterize. The formal principle of the series rests upon the
cyclopentadienyl-imido analogy. Like the parent compound
5,19’ 6-8 can be synthesized by reaction of the metal nucleophile
[CpFe(CO),]- with the organometallic Lewis acids [CpW( N ~ B u ) , ] + , [ ” ~[C~MO(N~BU),]+,[”]
and [Cp,Nb(NfBu)]+ [‘I
(Scheme 3). The spectroscopic data of 6-8 clearly indicate a
nonbridged metal-metal bond, as is present in [ (tBuN),ReM O ( C O ) ~ C P ] [ ~and
]
[Cp*(O),W-W(CO),Cp*] (Cp* = 17’CsMe,) (Table 1).[161The results make it seem plausible that the
imido complex fragments depicted at the bottom of Scheme 1
are not only isolobal to one another, but that they should also
have similar valence orbitals to a (R,E) group (E = Si, Ge, Sn)
or the 17VE carbonyl complex fragments.[”]
4
3
Scheme 2. The bonding capability of electronically related imidoyl complex t‘rasments [Cp,,M’(NR),] of Groups 5 and 6. a) [Mo(N/Bu),CI,]. b) [W(NtBu),C12(py)2],c) [CpNb(NrBu)CI2].d) [CpTa(N/Bu)CI,]. R = rBu. py = pyridine.
5
QlK
Fe
oc’
these d-metal acids are electronically related, and the isolobal
relationship with the carbonyl complex fragments is thereby established. On the basis of the spectroscopic data of 1-4 (Table 1).
the presence of bridging ligands can be excluded. On the other
hand, according to the isolobal principle[’01the characterization
of 1-4 sets up a conceptual bridge between the doubly metalated zirconocene [Rul-[Cp,Zr]-[Ru], described by Casey et al.
([Ru] = [CpRu(CO)J1’‘I) and stannylene-bridged complexes of
the type [MI-[SnR,]-[MI ( M = Fe, Ru, Mo, etc).[”]
We now contrast this series of-in the broadest sense-carbene-like[l3I imido complex fragments with a series of radical
complex fragments (Scheme 1, bottom). The radical fragments
have not yet been isolated as monomeric d’ species; however,
they form homonuclear, diamagnetic dimers by direct M -M
coupling.”. l 4 I similar to 17VE metal carbonyl complex fragments. Cross dimerization of these metal radicals with the 1 7 V E
‘co
8
7
Scheme 3. The bonding capability of electronically related iinidoyl complex fragments [Cp,M’(NR),] of Groups 5-7. a) [Re(NtBu),Cl], b) [CpW(NtBu),CI], c )
[CpMo(NrBu),CI], d ) [Cp,Nb(NtBu)Cl]. R = [Bu.
Table 1 summarizes selected spectroscopic data of the complexes 1-8. which have also been characterized by elemental analysis. A comparison of the position of the IR bands v,(C=O) and
v,,(C=O) in complexes of the type [M”]-[Fe(CO),Cp] allows
conclusions to be drawn about the decrease of electron den-
Table 1. Experimental data of 1-8.
Crnpd. (R
L
=
rBu)
V(CO) [a1
v(M=NC) [b]
d(C,)
6(C,)
A6 [c]
M + [d]
Color. yield. m.p.
1978 s. 1969 vs.
1926 vs
1247 s
1204 s
68.78
31.83
36.95
593.8
orange. 71 %,
144 “C [f]
1983 s, 1976 vs,
1930 vs
1281 s
1241 s
67.60
32.45
35.15
681.3
yellow, 79%.
226 ’C [f]
1952 vs, 1916 vs.
1900 s
1235 s
70.02
32.20
37.82
584.0
orange-red, 71 YO.
120 “C [f]
1950 vs, 1915 vs,
1901 s
1253 s
68.24
32.20
36.04
671.6
orange-yellow, 21 “Yo,
170 “C [f]
1994 vs
1949 vs
1229 s
1211 s
67.63
31.34
36.29
577.2
yellow, 83%.
105 T
1977 vs
1927 \is
1282 s
1244 s
66.95
31.89
35.06
568.0
yellow, 56%
74 ‘C
1972 vs
1925 vs
1246 s
1219 s
68.43
31.07
37.36
481.8
orange-yellow. 66%,
53 “C [f]
1956 vs
1908 vs
1231 s
69.72
31.05
38.67
470.7
orange-yellow. 35 %.
102 ‘C [f]
[a] I n cm-’: 1.5, and 7 in n-hexane. all others in methylcyclohexane; for comparison: [Me,Sn{Fe(CO),Cp),] 1989. 1978, 1946, 1935 in cyclohexane [12a]; [H-Fe(CO),Cp]
2013, 1949 in MeCN 1181; [Me$-Fe(CO),Cp]
1994, 1913 in hexane [17b]; [(Me,N),Ti-Fe(CO)ZCp] 1948, 1898 in octane 1191. [b] In cm-’; Nujol mull. [c] 13Cj1H)N M R
(100.6 MHz); 1.5, and 7in CDCI,. all others in C,D, C , = CMe,. C, = C M e , . A6 = 6(C,)-6(C,): relative measure for the M E N character [24]. [d] El-MS (70 eV); highest
peak of the pattern reported. correct isotope distribution. [f] Decomposition.
1256
c l i u f i0.69451 Wrinhcbii, 1994
’i VCH V e r / u ~ s ~ r ~ s i ~ / / smhH,
S. /0.00+ 2 . 0
0570-0(333~94~12/2-1256
A n g r ~ Cliem.
.
In/.Ed. Engl. 1994, 33, N o . 12
COMMUNICATIONS
a) A. D. Poole, V. C. Gibson, W. Clegg, J. Cliem. Soc. Chem. Commun. 1992,
237-239; b) P. W. Dyer, V. C . Gibson, J. A. K. Howard, B. Whittle, C. Wilson,
ihid. 1992, 1666-1668; c) J. K. Cockcroft, V. C. Gibson. J. A K . Howard,
A. D. Poole, U. Siemeling. C. Wilson, ihrd. 1992, 1668-1670.
J. Sundermeyer, D. Runge. J. S. Field, Angrbv. Chem. 1994. 106. 679-682:
Angew. Chem. Inr. Ed. Engl. 1994,33,678-681.
a) M. Elian, R. Hoffmann, Inorg. Chcm. 1975, 14, 1058-1076; b) R. Hoffmann, Angew. Chem. 1982,94,725-739;Angew. Chem. I n ( . G I . Engl. 1982.21.
711-725; c) F.G.A. Stone. ibid. 1984. 96, 85-96 and 1984, 24. 89-100.
P. P. Casey, R. F. Jordan, A. L. Rheingold, Orgunumetul/ic.r 1984.3.504-506:
the directly comparable iron complex [MI = [CpFe(CO),] decomposes thermally at as low a temperature as -20°C.
a) N. Flitcroft. D. A. Halbourne, U. Paul. P. M. Tucker. E G. A. Stone, J.
Chcni. Soc. A 1966, 1130-1133; b) K. Triplett. D. Curtis. Inorg. Clicm 1976,
I S , 431 -~433.
and references therein.
The carbene-like character of [q5-C,H,),Ti] was underpinned by EHMO calculations: H. H. Brinzinger, L. S. Bartell. J. An?. Chem. Soc. 1970,Y2.1105- 1107.
In contrast to a carbene, the inorganic carbene analogues in Scheme 1 have a
third, energetically low-lying orbital ( u , in the case of titanocene). that can be
available for an additional interaction with concomitant increase in the coordination number at the metal center (Ti, Nb, Mo, Sn. etc.): J. W. Lauher, R.
Hoffmann. ibid. 1976,98, 1729-1742: see also [7].
a) A. K. Burrell. J. C. Bryan, An,qw. Chem. 1993, 105. 85-86. Angew. C%em.
Int. G I . Ennl. 1993,32,94-95;b) A. A. Danopoulos. C. J. Longley, G. Wilkinson. B. Hussain. M. B. Hursthouse. Po!v/?edron 1989,8,2657~
2670:c) J. Sundermeyer, U. Radius, P. Mountford, unpublished.
a) J. Sundermeyer, Clwm. Ber. 1991,124,1977-1979;b) U. Radius, J. Sundermeyer. ihid. 1992,125,2183-2186;c) J. Sundermeyer. U . Radius. C. Burschka.
&id. 1992,125. 2379-2384.
H. G . Alt, H. I. Hayen, R. D. Rogers, J. CAem. Soc. Chem. Commnn. 1987,
1795 1796.
Representative examples of comparab~e[MI-ER, complexes (E = Si, Ge, Sn):
a) W. Malisch, M. Kuhn, Chem. Ber. 1974, 107,979-995: b) J. W. Faller. B. V.
Johnson, C. D. Schaeffer. Jr.. J. Am. Chem. Sor. 1976, 98. 1395-1400. and
references therein.
E. J. Moore, J. M. Sullivan. J. R. Norton, J. An?. Chcm. Soc. 1986. IOX. 22572263.
W. J. Sartain. J. P. Selegue. Orgunomrrullres 1987. 6. 1812-1815. The metal
acidity of [(R,N),Ti]+ can be enhanced, for example by N-silyl and N-arqlamid o ligands: S. Friedrich, H. Memmler, L. H. Gade, W.-S. Li. M. McPartlin,
Anpew. Cliem. 1994, 106, 705-708: Angew. Chem. Inf. €d. En$ 1994. 33.
676-678.
D. S. Williams, R. R. Schrock. OrgunumPtullrcs 1993. 12. 1148 1160.
G.Parkin, A. van Asselt. D. J. Leahy. L. Winuery. N. G. Hua, R. W. Quan,
L. M. Henling, W. P. Schaefer. B. D. Santarsiero. J. E. Bercaw. Inorx. C'hem.
1992,31, 82-85.
A. N. Chernegd, M. L. H. Green, A. G. Suarez, J. Chrm. Soc. Daltofz Pun.\.
1993,3031 -3034.
S. R. Huber. T. C. Baldwin, D. E. Wigley, Organnmrtullrcs 1993. 12. 91-97.
W. A. Nugent. R. J. McKinney. R. V. Kasdovski. F. A. Van-Catledge. Inory.
Chim. Aclu 1982. 65, L91 -L93.
sity induced by the metal acid [M"] at the neighboring metal
center. The following qualitative ordering of the acceptor character of the cationic Lewis acids [M"]"+ can be derived from the
extent of the backbonding to the CO ligands (Scheme 4, Table 1.
cf. footnote [a]). A similar comparative look at the CO vibra[SnMe,12+ > [W(N/Bn),IZt
[HI' > [SnMe,]'
[Mo(NrBu),12+ > [CpTa(NtBu)IZi
1[CpNb(NfBu)]'+
E [Re(NtBu),]+
> [ C p w ( N f B ~ ) ~zl +[CpMo(N/Bu),]'
> [Ti(NMe,),]+ > [Cp2Nb(NtBu)]+
Scheme 4 The acceptor character decreases from left to right
tional bands shows that the oxidation state, despite its formal
nature, makes a larger contribution to the Lewis acidity of cationic
metal acids-for
example [(tBuN),Re]+ in contrast with
[ (Me,N),Ti]
'I-- -than the position of the central atom in the
periodic system. It is, after all, the ligands that influence the acceptor character of a metal center decisively by their n-donor ability.
In this context the amido (NMe,) and cyclopentadienyl ligands
($-C,H,) are stronger donors than the imido ligand (NtBu).
It is worth mentioning that the reactivity of the anion
[Re(NAr),]- (Ar = 2,6-iPr,C6H,) resembles that of the
carbonyl metalates [Cp,M(CO),]-.[201 As a result protonation
yields a hydride complex with an acidic hydrogen atom. In
this regard a comparison with [R,Sn-HI is also obvious.
The hydride complexes [(gs-C,Me,),(PhN)Ta-H],[211
[($C H ,) ( f BuN)Nb -HI ,["I
and [ ( q5-C,Me 5 ) 2 (ArN)W - HI [' I
that are isoelectronic with [(ArN),Re-HI in the sense of the
thesis presented here were also described recently.
Both the reviewed results on hydrides and our own suggest the
isolobal relationship formulated in Scheme 1, which is derived
from the following rule: If in a complex fragment [(q5-C,R,)M]
the ligand qS-C,R, is substituted for NR and the central atom
d"-M ( n = 0, 1. 2) is replaced by an isoelectronic metal center
d"-M' from the next higher group of the periodic table, a complex fragment [(RN)M'] that has the same number of valence
orbitals and valence electrons, and valence orbitals of similar
symmetry and energy results.
+
-
,
Received: December 9, 1993
Revised version: January 28, 1994 [Z65491E]
German version: Angrn.. CAem. 1994, 106. 1328
[ l ] S. Schmidt. J. Sundermeyer. J. Organornet. Cliem.. in press.
[?I D. S . Glueck. J. C. Green. R. 1. Michelman. 1. N. Wright. Orgunomerullrcs
1992. / I . 4221 -4225.
(31 The "closed-shell anion" R N 2 is considered a six-electron donor to a d"-metal
cation. and the "nitrene" R N a four-electron ligand to a metal atom. Irrespective 0 1 M. hether the hetero- o r homolytic view is favored, a maximum of one o
and two TI bonds to the metal is possible. A comparable statement is valid for
the sir- and five-electron donors (q5-C,H,)- and ($C5H5)'. In complexes
with beberal competing a donors, the bond order deviates from the maximum
value of 3 depending on the molecular symmetry. The bond description
M = N R chosen consistently in this paper includes the high triple-bond component M = N R that is typical ford-electron-poorcomplexes:W. A. Nugent. J. M.
Mayel-. b"~/uI-LipiidMulrtplr Bonds, Wiley. New York, 1988.
[4] a) T. R. Cundari. J. A m . Chrm. Soc. 1992.114.7879-7888: b) K. A.Jnrgensen,
lnnor,q Clwm. 1993, 32. 1521 -1522: c ) T.R. Cundari, J. Am. Chem. Soc. 1992.
114.10557-10563:d)M. H.Schofield,T. P. Kee,J. T.Anhaus,R. R. Schrock,
K . H Johnson. W. M. Davis, Inorg. Chem. 1991.30.3595-3640:e) see also [6],
[7]and [20]
[5] If the two ligands approach the metal center along the :axis. orbitals of the
same sqnimetry interact: 0. 271-donor RN'-: N(sp hybrid, p,, s) +
M(d,:. p,. s l . N ( p J + M(d,,, pJ. N(pJ + M(d,,. pJ. (5. 2 a-Donor C,H,-:
CS(NI. ([J M(d,,. P,. s):
Cde,) M(d,,. PJ; Cs(e1) M(d,,, P,). A
6-hackhond M(d,,, d+,:) -C,(e,) has no or a comparatively small significance in d-electron-poor complexes of d" ( t i = 0, 1 , 2) configuration.
[6] a ) D. S. Williams. M. H. Schofield, J. T. Anhaus. R. R . Schrock, J. A m . Chenz.
Soc. I9YU.112.6728-6729:b) D.S.Williams, M. H. Schofield, R. R. Schrock.
Org~iffoi?fe/ullr~~.s
1993. 12, 4560-4571.
[7] D . N. Williams. J. P Mitchell, A. D. Poole, U. Siemeling,,W. Clegg. D. C. R.
Hockless. P. A. ONeil. V. C. Gibson. J. Chem. S o t . Dalron T,uns. 1992.739-751.
+
+
Angen.. Clwm. I i t t . G I . EngI. 1994. 33. N o . 12
+
T'
A Novel Organomagnesium Compound
Consisting of Two Triple-Decker Cations
[LMg(p-Me),MgL] and an Octamethyltrimagnesate Anion: [{Me,Mg(p-Me),},Mg]Z - **
+
Heiko Viebrock, Ulrich Behrens, and Erwin Weiss*
Dedicated to Professor Hansjorg Sinn
on the occasion of his 65th birthday
The polymer chains [MgR,], (R = Me, Et, Ph) found in solvent-free diorganomagnesium compounds are disrupted by
bases L (L = ether, amine) with the formation of primarily
['I
[**I
Prof. Dr. E. Weiss. Dr. H. Viebrock, Prof. Dr. U . Behrens
lnstitut fur Anorganische und Angewandte Chemie der Universitit
Martin-Luther-King-Platr 6, D-20146 Hamburg ( F R G )
Telefax: Int. code + (40)7222247
Alkyl- and Arylmetal Compounds, Part 52. This research was supported by the
Fonds der Chemischen Industrie. We thank Prof. K. Weighardt. Universitlt
Bochum, for the gift of N,N',N"-trimethy1-l.4,7-triazacyclononane
L. Part
51: [l].
VCH V e r / u , z ~ p ~ ~ . ~ ~ ~ mhH.
l l v t . h u0.69451
ff
Weinheim, 1994
~
0570-0833:'94/1212-I257
B 10.00 + .2S!0
1257
Документ
Категория
Без категории
Просмотров
5
Размер файла
379 Кб
Теги
bonding, 5ц7, complex, isolobal, capability, group, imide, fragmenty, regard, relationships
1/--страниц
Пожаловаться на содержимое документа