Photoinduced Mo−CN Bond Breakage in Octacyanomolybdate Leading to Spin Triplet Trapping

Abstract

The photoinduced properties of the octacoordinated complex K4MoIV(CN)8⋅2 H2O were studied by theoretical calculations, crystallography, and optical and magnetic measurements. The crystal structure recorded at 10 K after blue light irradiation reveals an heptacoordinated Mo(CN)7 species originating from the light‐induced cleavage of one Mo−CN bond, concomitant with the photoinduced formation of a paramagnetic signal. When this complex is heated to 70 K, it returns to its original diamagnetic ground state, demonstrating full reversibility. The photomagnetic properties show a partial conversion into a triplet state possessing significant magnetic anisotropy, which is in agreement with theoretical studies. Inspired by these results, we isolated the new compound [K(crypt‐222)]3[MoIV(CN)7]⋅3 CH3CN using a photochemical pathway, confirming that photodissociation leads to a stable heptacyanomolybdate(IV) species in solution.

Large Breathing Effect Induced by Water Sorption in the Exceptionally Stable Nonporous Non-MOF Crystalline Material

“…The octacyanomolybdate(IV) anion was previously demonstrated to behave as an intrinsic photomagnetic chromophore in several bimetallic CN-bridged systems. [101][102][103] Therefore we decided to study the photomagnetic properties of 1Mn and 1Mn•8H2O at low temperatures. Both compounds strongly respond to 450 nm irradiation at 10 K with a 13-fold increase of magnetization in the case of 1Mn and a 16-fold increase for 1Mn•8H2O (Figure S26).…”

Photoinduced magnetic hysteresis in a cyanide-bridged two-dimensional [Mn2W] coordination polymer

“…Very recently, Pinkowicz and Mathonière et al found that light irradiation can induce the singlet to triplet transition in K 4 [Mo IV (CN) 8 ] accompanied by reversible dissociation/recombination of the Mo-CN bonds. 44 It is worth mentioning that the observed photoinduced triplet state was quite stable for several hours even at room temperature. Although the singlet (S = 0) to triplet (S = 1) state transition of the building block of [W IV (CN) 8 ] 4− was reported in a {Mn 2 W} 1D chain 57 and two {Mn 2 W} 3D networks, 58,59 the number of [W IV (CN) 8 ] 4− based compounds exhibiting photoinduced singlet to triplet transitions is still limited.…”

“…This is not only due to the variable dimensionalities of its architecture but also its characteristic photomagnetic behavior showing the singlet (S = 0) to triplet (S = 1) transition. [44][45][46][47][48][49][50][51][52][53][54][55][56] The photomagnetic action of octacyanotungstate(IV) is related entirely to itself in contrast to other photoinduced W-3d systems. Very recently, Pinkowicz and Mathonière et al found that light irradiation can induce the singlet to triplet transition in K 4 [Mo IV (CN) 8 ] accompanied by reversible dissociation/recombination of the Mo-CN bonds.…”

Experimental and theoretical insights into the photomagnetic effects in trinuclear and ionic Cu(ii)–Mo(iv) systems

“…5) 32,35,60 or the photodissociation of the single cyanide leading to a reduction of the coordination number to 7. 34,57 Overall, both MMCT and LIESST mechanisms lead to an increase of magnetic susceptibility in the χ M T (T ) plots due to the formation of ferromagnetically coupled domains, but the similarity ends there. 27 The photomagnetic effect following the MMCT mechanism does not produce any additional spins, just relocates them (the M S after photoirradiation remains constant), and usually progresses much faster.…”

“…Nevertheless, the latest studies confirming the unquestionable presence of the photomagnetic effect for the octacyanidomolybdate salts [56][57][58][59][60] prompt us to investigate the photomagnetic effect in Cu(II)-Mo(IV) ionic systems. In addition, they can be a platform for simultaneous theoretical and experimental studies on the photomagnetic effect, which has not been used so far due to computational limitations (too large complexity of the systems) or a lack of suitable samples.…”