3 Illscvier Sc
73
-Joto-r1a1 of O,-g(~r~or,lc&(~ilic~Cflet~~i.s&,-~. 175 (19’79) 3
Illscvier Sc d’ > d”. For complexes with isopropyl groups attached to the diimine ligands a
TABLE ‘H-NBIR
2 CHEMICAL
SOLUTIONS ~(PPI-II) Compound(R1.
SHIFTS RELATIVE
Mn(CO)+ln(C0)3(i-pr.
H. CHJ) H, H)
Mn~CO)5Mn(C0)3(~-methox~. ~~n .J), and for one of the two inequivalent less than the coupling in the isopropyl
Sl
isopropyl g5yoi~ps in crompound VI situation (b) was observed (i.e., A6 2~ J). The results show that the chemical shift. differences of the methyl groups of the isopropyl derivatives strongly depend on the substituents causing the asymmetry in the comple.scs_ -Additional information about the diastereotopic effect was obtained by 13C NRIR spectroscopy. The chemical shift differences for the methyl groups of the isopropyl substituents in the mononuclear halide complexes were less than 0.7 pprn, while in the binuclear species chemical shift differences up to 6 ppm were observed (see Table 3). The line splitting in the NMR pattern of the isopropyl groups has also been observed in other binuclear metal carbonyl DAB complexes [ 361 and in complexes containing ligands derived from DAB [ 31. The effect seems to give useful structural information.
UV-visible spectroscopy The Mn(CO)&I’(CO),(DAB) complexes (M’ = Mn, Re) are all highly coloured in solution and have comples electronic absorption spectra in the visible and the near UV. Between 300 and 650 nm charge transfer (CT) transitions between the metal and the DAB ligand, intra-ligand (IL) transitions on the aromatic rings of substituents, and (T-+ o* transitions localised in the metal-metal bond have been observed, and will be discussed below. In principle there exist six CT transitions from the three dz-orbitals to the two ligand x* orbitals. All these k-ansitions are symmetry allowed as is obvious from Fig. 5. Characteristic of the CT transit.ions between the metal dn orbitals and the DAB ligand z* orbitals in metal car-bony1 complexes is the strong solvent dependence of the position of the absorption maxima C1,37-39). For Mn(CO),iV’(CO),(D,4B) complexes (W’ = MN, Re) a small shift to shorter wavelen$h is observed for the CT transitions to the ~“(a’) level with increasing polarity of the solvent (positive solvatochromism) while for the transitions to the ~*(a”) level the shifts are uncertain because of overlap with other bands. The effects of charge on the wavelengths of the CT transitions are shown in Table 4.
II . ,:a
L
” l-l*
M
d,2
\ ,
,-I,’ _*< : ,‘. ,’
T-r*
L
\ .
\ ,
, _’
,*
a”
\
a’
\ ‘;-A--
__;‘M
\, . \ a’ +--;+-& ‘, a” +,H’ .
part of a tentative
d,2
dxz dxy
1
d,,
M’
,:
\ ‘,,“” .,,..$
Fig. 5. Relevant t-
a’
\ .n * \ \
.:
t:
a*
,’
MO-scheme
which is in agreement
with the observed
W-visible
spec-
a CT transltions
Pcntane Pentane/etlm lxhcr DMF’
642 640 634 626
-CT1 a 380 380 378 365
CT2 59 G B9G 590 676
CT1
-- -
-
_
-
_ _ _ __ -
430(sh) 42 5(lih) 4:Io(sh) IlO
CT?
BANDS OF SOME IvI(CO)~M’(CO)~(DAW
to n” lewd. ’ 11~0,= not obscrvcd.
b
OP THE CT ADSORPTION
to n’ Icvcl, ’ CT trnnsitlons
(l/l)
SOLVATOCHROMISM
TABLE 4
GO4 G0 11 GO4 ti00
C’I’(
COMI’LBS12S (A, nnl)
---_---.C____._____
11.0.I! ,,.I). 11.0. 11,o.
C’I’~
83
ELECTRONIC (,\,l,ax IN nm)
ABSORPTIOS XT ROON
BIAXIMA
R2, R;)
C~~IP.N~~!R,.
CT(a’)
RInz(CO)s(i-pr, H, H) JInz(CO)s(i-pr. H. CH3) Mn7_(CO)s@-tol. H. H) ~In2(CO)s(l~-CZ130-phcn. H. H) ?.In(CO)~Re(C0)3(i-p)r. H. H) aIn(CO);hle(CO),(p-tol. H. H) n sh = shoulder.
OF BI~(CO)S~I’(CO)~DAB(~I’
= &In, Re) Ih’ EPA
SOLUTIONS
TENPERATURE
550. 375(sh) 570 604 606, 560(sh) 530, 450(sh) 592
most of which become
u
more pronounced
CT&x”)
71-
350(sh) 360(sh) 415(sh) 340,310 38O(sh) 120
--366 380 376
il* (IL)
(7 -
o*(LF)
336 337 337 331 339 n.o. b
at 100 K. * n.o. = not observed.
At 370 nm an intra-ligand (IL) transition (sT+ x”) has been observed fcr complexes containing aromatic substituents on the DAB ligand. The characteristic (T + G* transitions localised on the metal-metal bond appear at 330 nm, which is at almost the same position as that for Mn2(CO)l,,. Only for complexes with substituents fraansto the metal-metal bond is shift in the band position expected [ 24,251, and thus an absence of shift’ is in agree-.ient with the proposed structure. In Table 5 the positions of the absorption maxima (or shoulders) are listed.
A
T
Fig. 6. Low
temperature
behaviour
of the o -f u* transition
of Mn2(CO),
o_
s5
L
0
1..~.1~.~.,~,.‘,~...,..~.,.‘..,‘..’,....
300
100
)
500
600
700
)
500
6W
700
Awn)
300
400 hwm)
Fig-Y_ The UV-risible spectra of iMn2(CO)6(DAB) (DAB = i-pr-N=CHCH=N-i-pi-, p-anisidvl) in EPA at room temperature (a) and 100 K (b).
p-ak.idyL-N=CHCH=N-
will be studied with resonance Raman spectroscopy for Mo.(CO),IAE complexes [IAE = bis(p-l-alkylamino-2-alkylimino)ethane-N,N’] which are more photochemically stable. Conclusion It has been shown that although DAB ligands areclosely related to bipyridine and IJO-phenanthroline, they can behave differently in many types of reactions. Further evidence is found for the importance of the substituents on
the imine slielet.on with respect to the reactivity okf rhr ligands and the t llt~lX1Xl stability of t.he complexes. The manganese carbonyl D_AB conq~ltw~s W~I-P noi 1~reuioL~A~ knotvn in the range of metal carbonyl DAB con~pleses. _Xow it has Iwen shown that the n-interaction between the metal and the D,\B ligand for these cl’ ccml’leses falls between the x-interact.ions in d” and cl” cornpleses. The possible intramolecular reaction between the hI.n(CO)5 fragment and the coordinated ligand does not occur. 1Vit.h respect to the attack on the C=S bond the M(CO),RI’(CO),(DAB) complexes (XI’ = Mn, Re) differ from the binucle:u ds Fe,(CO),DAB con~pleses in \vhich the D_AB Iiganci is a six electron donor system _ References 1 2 3 4 5 6 7 8 9 10 11 12
L.H. Staal, D.J. Stufkens and A. Oskam. Inorg. Chim. Acta. 26 (19i8) 255. L-H. Staal. A_ Terpstra and D..J_ Stufkens. Inorg. Chim. _Acta. 34 (1979) 97L.H. StanI. A. Oskam and K. Vrieze. Incwp_ Chem.. in press. L.H. StaaI. A. Oskam and K. Frieze. .I. Organometal. Chcm.. 170 (1999) 235. H. Friedel. 1-W. Renk and H. tom Dieck. J. Organomctal. Chem.. 2ti (19il) 2li. 1-W. Rcnk and H. tom Dieck. Chem. Ber.. 105 (1972) l-103. R.W_ Balk. D.J. Stufkens and -4. Oskam. Inorg. Chim. _-t&l, 28 (1978) 133. -4-T-T. Hsieh and B-0. West. J_ Organometal. Chem.. 112 (1976) 285. A.J. Graham. D. Akrigg and B. Sheldrick. Crysr. Struct. Comm.. 6 (1977) 253. S. Otsuka. T. Yoshida and A. Nakamura. Inorg_ Chem.. 6 (1967) 20. H. tom Dieck and A. Orlopp. Angew. Chem., 13 (1975) 251. M.A. De Paoli. H-W. Friihauf, F.W. Grevel, E.-A_ Kocmer van Gustorf and W. Riemer. .I. Organometal. Chem.. 136 (1977) 219. 13 L.H. Staal and K. Vrieze. to be published. 14 H. Bock and H. tom Dieck. Angew. Chem.. 78 (1966) 549. 15 H.D_ HausenBnd Ii_ Krogmann. Z. Anorg. AIIg. Chem.. 389 (1972) 217. 16 D. Walther. Z. Chem.. 15 (1978) 72. 17 H. v-d. Poel. G. van Koten and K. Frieze. J. Organometi. Chem.. 135 (1977) C63. 18 H. v.d_ Poel. G. van Koten and K. Vriezc. to be published_ 19 H.W. Ftihauf. A. Landers, R. Goddard and C. Kriiger. Anger. Chem.. 90 (1978) 56. 2G A.J. Graham. D. AkrIgg and B. Sheldrick. Cryst. Struct. Comm.. 6 (19ii) 571. 21 A.J_ Graham. D. Akrigg and B. Sheldrick. Cryst. Struct. Comm_. 6 (1977) 5ii. 22 J.E. Ellis and E._4. Flom. J. Organometal. Chem.. 99 (1975) 263. 23 P. Lemoine and M. Gross. .I_ OrganometalChem.. 133 (1977) 193. and references therein. 24 25
D.L. D.L.
Morse and MS. Morse and MS.
Wrighton. Wrighton,
J_ Amer. Chem. .I. Organometal.
Sot., 98 (1976) 3931. Chrm.. 125 (1977) 71.
U. KoeIIe. J. Organometal. Chem.. 133 (19ii) 53. 27 U. Koelle. J. Organometal. Chem.. 155 (1978) 53. 28 R.E. Dossy. P.M. Weissman and R.L. Pohl, J. Amer. 26
29 30
Chem. Sot., 88 (1966) 347. R-E_ Dessu, R-L. Pohl and R-B_ King. J_ Amer. Chem_ Sot.. 88 (1966) 5121. R-E. Dessy and P.M. Weissman. J. Amer. Chem. Sot.. 88 (1966) 5124.
31 R.E. Dessy and P.M. Weissman. J. Amer. Chem. Sot.. 88 (1966) 5129. 32 E.W. Abel and G. Wilkinson, J. Chem. Sot.. (1959) 1501. 33 H. tom Dieck. K.D. Franz and F. Hohmann. Chem. Ber.. 108 (1975) 163. 34 H. tom Dieck. 1-W. Renk and K.D. Franz. J. Organometal. Chem.. 94 (1975) 417. 35 D. Liebfritz and H. tom Dieck. J. Organcmetal. Chem.. 105 (1976) 255. 36 L.H. StaaI. G. van Koten and K. Vrieze. to be published. 37 H. tom Dieck and I-W_ Renk, Angew. Chem., 82 (19’72) 805. 38 H. tom Dieck and I-W_ Renk. Chem. Ber.. 104 (1971) 110. 39 D. Waiter. ZPrakt. Chem., 316 (1974) 604. 40 MS. Wrighton and D.S. Ginley. J. Amer. Chem. Sot.. 97 (1975) 2065. 41 MS. Wrighton and D.S. GinIey, J. Amer. Chem. Sot.. 97 (1975) 4246. 42 D.S. Ginley and MS. Wrighton. J. Amer. Chem. Sot.. 97 (1975) 4980. 43 H-B. Abrahamson. C.C. Frazier. D-S. GinIey. H.B. Gray. J. Lilienthal, D.R. Tyler and MS. Inorg. Chem.. 16 (1977) 1554. 44 R-A. Levenson. H-B. Gray and G.P. Ceasar. J. Amer. Chem. Sot.. 92 (1970) 3654. 45 R-W. BaIk. D.J. Stufkens and A. Oskam. to be published.
Wrighton.
