Chiral $(LH)_2L_2Cu_3$ trinuclear paramagnetic nodes in octacyanidometalate-bridged helical chains

Trinuclear chiral $(LH)_{2}L_{2}Cu_{3}(LH = 1,3-diamino-2-propanol, bdapH)$ assemblies linked by octacyanidometalate(IV) form isostructural one-dimensional (1D) chains consisting of right- and left-handed helixes arranged in an alternate manner: $[(bdapH)_{2}(bdap)_{2}Cu^{II}_3][M^{IV}(CN)_{8}]\cdot H_{2}O$ (M=Mo 1, W 2). Each chain displays helicity with a long pitch around 17.2 \AA. The direction of the helix rotation is strictly connected with the conformation of the $(LH)_{2}L_{2}Cu_{3}$ unit. Right-handed helixes are based on $\Delta - S,S-(LH)_{2}L_{2}Cu_{3}$, whereas left-handed ones contain $\Lambda -R,R-(LH)_{2}L_{2}Cu_{3}$ units. Magnetic studies reveal antiferromagnetic interactions through alkoxo-bridges inside trinuclear Cu(II) nodes leading to an $S_{\top}=1/2$ ground state for both assemblies.