The preparation of the varieties of five-coordinate sixteen-electron manganese(I) complexes [Mn(CO)
3(-EC
6H
4-
o-E'-)]
- (E = Te, Se, S, O; E' = NH, S, O) by (a) oxidative addition of 2-aminophenyl dichalcogenides toanionic manganese(0)-carbonyl, (b)
![](/images/gifchars/pi.gif)
-donating ligand metathesis reaction of complex [Mn(CO)
3(-TeC
6H
4-
o-NH-)]
-, and (c) reduction /deprotonation of the neutral dimetallic [(Mn(CO)
3)
2(
![](/images/entities/mgr.gif)
-SC
6H
4-
o-S-S-C
6H
4-
o-
![](/images/entities/mgr.gif)
-S-)]/[(CO)
3Mn(
![](/images/entities/mgr.gif)
-SC
6H
4-
o-NH
2-)]
2 proved successful approaches in this direction. The IR
CO data of thecoordinatively and electronically unsaturated [Mn(CO)
3(-EC
6H
4-
o-E'-)]
- (E = Te, Se, S, O; E' = NH, S, O)complexes suggest the relative order of
![](/images/gifchars/pi.gif)
-donating ability of the series of bidentate ligands being [TeC
6H
4-
o-NH]
2- > [SeC
6H
4-
o-NH]
2- > [SC
6H
4-
o-NH]
2- > [SC
6H
4-
o-S]
2- > [SC
6H
4-
o-O]
2- > [OC
6H
4-
o-O]
2-. ProtonNMR spectra of the [Mn(CO)
3(-EC
6H
4-
o-NH-)]
- (E = Te, Se, S) derivatives show the low-field shift of theamide proton (
1H NMR (C
4D
8O):
![](/images/gifchars/delta.gif)
9.66 (br) ppm (E = Te), 9.32 (br) ppm (E = Se), 8.98 (br) ppm (E = S)).The formation of the dimetallic [(CO)
3Mn(
![](/images/entities/mgr.gif)
-SC
8N
2H
4-
o-S-)]
22- can be interpreted as coordinative associationof two units of unstable mononuclear [(CO)
3Mn(-SC
8N
2H
4-
o-S-)]
- and reflects the
![](/images/gifchars/pi.gif)
-donating ability of thebidentate ligand is responsible for the formation of pentacoordinate, sixteen-electron manganese(I) carbonylcomplexes. The neutral bimetallic manganese(I)-bismercaptophenyl disulfide complex [(Mn(CO)
3)
2(
![](/images/entities/mgr.gif)
-SC
6H
4-
o-S-S-C
6H
4-
o-
![](/images/entities/mgr.gif)
-S-)] with internal S-S bond length of 2.222(1) Å and the five-coordinate sixteen-electron complex[Mn(CO)
3(-SC
6H
4-
o-S-)]
- are chemically interconvertible. In a similar fashion, treatment of complex [Mn(CO)
3(-SC
6H
4-
o-NH-)]
- with HBF
4 yielded neutral dinuclear complex [(CO)
3Mn(
![](/images/entities/mgr.gif)
-SC
6H
4-
o-NH
2-)]
2 and showedthat the amine deprotonation is reversible. Investigations of
![](/images/gifchars/pi.gif)
-donating ligand metathesis reactions of complex[Mn(CO)
3(-TeC
6H
4-
o-NH-)]
- revealed that the stable intermediate, not the
![](/images/gifchars/pi.gif)
-donating ability of bidentate ligands,is responsible for the final protonation/oxidation product. This argument is demonstrated by reaction of [Mn(CO)
3(-TeC
6H
4-
o-NH-)]
- with 1,2-benzenedithiol, hydroxythiophenol, and catechol, respectively leading tothe formation of [Mn(CO)
3(-EC
6H
4-
o-E'-)]
- (E = S, O; E' = S, O), although any
![](/images/gifchars/pi.gif)
-donor containing theamido group is a more effective donor than any other
![](/images/gifchars/pi.gif)
-donor lacking an amido group. Also, the reactions of[Mn(CO)
3(-TeC
6H
4-
o-NH-)]
- with electrophiles occurring at the more electron-rich amide site support that themore electron-rich amide donor of the chelating 2-tellurolatophenylamido occupies an equatorial site as indicatedby a shorter Mn
I-N bond length of the distorted trigonal bipyramidal [Mn(CO)
3(-TeC
6H
4-
o-NH-)]
-.