TY - JOUR
T1 - Coordination chemistry of [2+2] Schiff-base macrocycles derived from the dianilines [(2-NH2C6H4)2X] (X = CH2CH2,O): structural studies and ROP capability towards cyclic esters
AU - Wang, Kuiyuan
AU - Prior, Timothy J.
AU - Hughes, David L.
AU - Arbaoui, Abdessamad
AU - Redshaw, Carl
PY - 2021/6/21
Y1 - 2021/6/21
N2 - Reaction of the [2 + 2] Schiff-base macrocycles {[2-(OH)-5-(R)-C
6H
2-1,3-(CH)
2][CH
2CH
2(2-C
6H
4N)
2]}
2(R = Me, L
1H
2;tBu, L
2H
2) with FeBr
2afforded the complexes [FeBr(L
1H
2)]
2[(FeBr
3)
2O]·2MeCN (1·2MeCN), [FeBr(L
2H
2)][X] (X = 0.5(FeBr
3)
2O,2·0.5MeCN, X = Br,3·5.5MeCN), respectively. Reaction of L
2H
2with [KFe(OtBu)
3(THF)] (formedin situfrom FeBr
2and KOtBu), following work-up, led to the isolation of the complex [Fe(L
2)(L
2H)]·3MeCN (4·3MeCN), whilst with [CuBr
2] afforded [CuBr(L
2H
2)][CuBr
2]·2MeCN (5·2MeCN). Attempts to form mixed Co/Ti species by reaction of [CoBrL
2][CoBr
3(NCMe)] with TiCl
4resulted in [L
2H
4][CoBr
4]·2MeCN (6·2MeCN). Use of the related oxy-bridged Schiff-base macrocycles {[2-(OH)-5-(R)-C
6H
2-1,3-(CH)
2][O(2-C
6H
4N)
2]}
2(R = Me, L
3H
2;tBu, L
4H
2) with CoBr
2led to the isolation of the complexes [(CoBr)
2(L
3)]·2C
3H
6O (7·2C
3H
6O), [Co(NCMe)
2(L
4H
2)][CoBr
4]·5MeCN (8·5MeCN), [Co(NCMe)
6][CoBr
3(MeCN)]
2·2MeCN (9·2MeCN). For comparative structural/polymerisation studies, the complexes {CoBr(NCMe)L
5}
2·2MeCN (10·2MeCN) and [Co(NCMe)
2L
5]
2[CoBr
3(NCMe)]
2(11), [FeBr(NCMe)L
5]
2·2MeCN (12·2MeCN) where L
5H = 2,6-(CHO)
2-4-tBu-C
6H
2OH, as well as the chelate-free salt [Fe(NCMe)
6][FeBr
3OFeBr
3] (13) have been isolated and structurally characterized. The ability of these complexes to act as catalysts for the ring opening polymerisation (ROP) of ε-caprolactone (ε-CL) and δ-valerolactone (δ-VL) was investigated, as well as co-polymerisation of ε-CL withrac-lactide (r-LA) andvice versa.
AB - Reaction of the [2 + 2] Schiff-base macrocycles {[2-(OH)-5-(R)-C
6H
2-1,3-(CH)
2][CH
2CH
2(2-C
6H
4N)
2]}
2(R = Me, L
1H
2;tBu, L
2H
2) with FeBr
2afforded the complexes [FeBr(L
1H
2)]
2[(FeBr
3)
2O]·2MeCN (1·2MeCN), [FeBr(L
2H
2)][X] (X = 0.5(FeBr
3)
2O,2·0.5MeCN, X = Br,3·5.5MeCN), respectively. Reaction of L
2H
2with [KFe(OtBu)
3(THF)] (formedin situfrom FeBr
2and KOtBu), following work-up, led to the isolation of the complex [Fe(L
2)(L
2H)]·3MeCN (4·3MeCN), whilst with [CuBr
2] afforded [CuBr(L
2H
2)][CuBr
2]·2MeCN (5·2MeCN). Attempts to form mixed Co/Ti species by reaction of [CoBrL
2][CoBr
3(NCMe)] with TiCl
4resulted in [L
2H
4][CoBr
4]·2MeCN (6·2MeCN). Use of the related oxy-bridged Schiff-base macrocycles {[2-(OH)-5-(R)-C
6H
2-1,3-(CH)
2][O(2-C
6H
4N)
2]}
2(R = Me, L
3H
2;tBu, L
4H
2) with CoBr
2led to the isolation of the complexes [(CoBr)
2(L
3)]·2C
3H
6O (7·2C
3H
6O), [Co(NCMe)
2(L
4H
2)][CoBr
4]·5MeCN (8·5MeCN), [Co(NCMe)
6][CoBr
3(MeCN)]
2·2MeCN (9·2MeCN). For comparative structural/polymerisation studies, the complexes {CoBr(NCMe)L
5}
2·2MeCN (10·2MeCN) and [Co(NCMe)
2L
5]
2[CoBr
3(NCMe)]
2(11), [FeBr(NCMe)L
5]
2·2MeCN (12·2MeCN) where L
5H = 2,6-(CHO)
2-4-tBu-C
6H
2OH, as well as the chelate-free salt [Fe(NCMe)
6][FeBr
3OFeBr
3] (13) have been isolated and structurally characterized. The ability of these complexes to act as catalysts for the ring opening polymerisation (ROP) of ε-caprolactone (ε-CL) and δ-valerolactone (δ-VL) was investigated, as well as co-polymerisation of ε-CL withrac-lactide (r-LA) andvice versa.
UR - http://www.scopus.com/inward/record.url?scp=85107925533&partnerID=8YFLogxK
U2 - 10.1039/D1DT00711D
DO - 10.1039/D1DT00711D
M3 - Article
VL - 50
SP - 8057
EP - 8069
JO - Dalton Transactions
JF - Dalton Transactions
SN - 1477-9226
IS - 23
ER -