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Reactions of heteroallenes with cyclam-based Zr(iv) complexesElectronic supplementary information (ESI) available: Tables with atomic coordinates for all optimized species and a more detailed discussion of the molecular structures of 5, 11, 16 and 18 are presented. CCDC 1010648-1010651. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4dt02851a
This work describes reactions of heteroallenes with diamido-diamine cyclam-based Zr( iv ) complexes of the general formula (Bn 2 Cyclam)ZrX 2 (X = O t Bu, 1 , O i Pr, 2 , SPh, 3 , NH t Bu, 14 ) as well as the di-orthometallated species ((C 6 H 4 CH 2 ) 2 Cyclam)Zr, 17 . The reactions of isocyanates...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Online Access: | Get full text |
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| Summary: | This work describes reactions of heteroallenes with diamido-diamine cyclam-based Zr(
iv
) complexes of the general formula (Bn
2
Cyclam)ZrX
2
(X = O
t
Bu,
1
, O
i
Pr,
2
, SPh,
3
, NH
t
Bu,
14
) as well as the di-orthometallated species ((C
6
H
4
CH
2
)
2
Cyclam)Zr,
17
. The reactions of isocyanates or isothiocyanates with
1
,
2
or
3
resulted in the formation of N-bonded ureate or thioureate cyclam complexes upon [2 + 2] cycloaddition of the Zr-N
amido
bonds of the cyclam to the heteroallene (
4-9
). DFT calculations showed that κ
2
-
N
,
N
′-ureate bonding is favoured over κ
2
-
N
,
O
-ureates, which in turn may be formed in reactions with bulky isocyanates as 1-naphthyl isocyanate (NpN&z.dbd;C&z.dbd;O). The reactions of
2
with
N
,
N
′-cyclohexylcarbodiimide (CyN&z.dbd;C&z.dbd;NCy) and carbon disulfide afforded guanidinate and dithiocarbamate fragments, respectively, appended to one of the nitrogen atoms of the cyclam ligand. These reactions represent a reliable method for the synthesis of asymmetrically N-functionalized cyclams giving rise to
C
1
symmetry Zr(
iv
) species by addition of one equivalent of heteroallenes. The reaction of (Bn
2
Cyclam)Zr(NH
t
Bu)
2
,
14
, with one equivalent of mesityl isocyanate (MesN&z.dbd;C&z.dbd;O) also proceeds through insertion, involving one Zr-NH
t
Bu bond. However, it was observed that the reaction of (Bn
2
Cyclam)Zr(NH
t
Bu)
2
,
14
, with MesN&z.dbd;C&z.dbd;O follows a different path if the reaction is carried out at 60 °C. In this case the reaction leads to [2 + 2] addition of the Zr-N
cyclam
bond to the isocyanate, with a concomitant occurrence of orthometallation of the one benzyl pending group of the cyclam ring. The reaction of
t
BuN&z.dbd;C&z.dbd;O with the di-orthometallated complex ((C
6
H
4
CH
2
)
2
Cyclam)Zr,
17
, also gave a κ
2
-
N
,
N
′-ureate fragment, by isocyanate addition to the macrocycle. DFT calculations on these systems were conducted in an attempt to rationalise the reactivity patterns observed.
Reactions of heteroallenes with cyclam-based Zr(
iv
) complexes are described. The products obtained revealed the formation of ureate, thioureate, guanidinate or dithiocarbamate cyclam derivatives upon [2 + 2] cycloaddition of the Zr-N
amido
bonds of the cyclam. DFT calculations clarified the reactivity patterns observed. |
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| ISSN: | 1477-9226 1477-9234 |
| DOI: | 10.1039/c4dt02851a |