SCHEDULED MAINTENANCE
Nitrogen- and carbon-based isomerism in the copper(II) complexes of 6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane-6,13-diamine
Abstract
A number of N- and C-based diastereomeric copper(II)
complexes of the pendant-arm macrocyclic hexaamines trans- and
cis-
6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane-6,13-diamine
(L
1
and L
2
) have been isolated and characterised.
The crystal structures of the complexes
RRSS-[CuL
1
(OH
2
)
2
][ClO
4
]
2
,
SSRR-[Cu(H
2
L
1
)(OClO
3
)
2
][ClO
4
]
2
·2H
2
O,
RSRS-[CuL
1
(OClO
3
)]ClO
4
,
RSRS-[CuL
2
(OClO
3
)]ClO
4
and
RRSS-[Cu(H
2
L
2
)(OClO
3
)
2
][ClO
4
]
2
have been determined. Some unusual
structural and spectroscopic variations are found across this series of
diastereomers. The protonation constants of the pendant primary amines
are dependent on the relative dispositions of the adjacent macrocyclic
secondary amine H atoms, which is indicative of intramolecular
hydrogen-bonding interactions.
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