Structural and dynamic properties of tetrahydroborate complexes

Binuclear Copper(I) Borohydride Complex Containing Bridging Bis(diphenylphosphino) Methane Ligands: Polymorphic Structures of [(µ2-dppm)2Cu2(η2-BH4)2] Dichloromethane Solvate

“…Additionally, stretching vibration of CuHBH cycle is a unique feature of {M(η 2 -BH 4 )} complexes [52,63]. Analysis of the data for copper(I) tetrahydroborate complexes shows that the 11 could not be accurately determined [63]. The XRD analysis of monocrystals obtained for this copper(I) tetrahydroborate compound revealed it is a binuclear complex bearing two dppm ligands bridging two {Cu(η 2 -BH 4 )} fragments.…”

“…The latter also exhibits two resolved or one broad BH term stretching vibrations at a higher frequency than {M(η 1 -BH 4 )} (Table 2). Additionally, stretching vibration of CuHBH cycle is a unique feature of {M(η 2 -BH 4 )} complexes [52,63]. Analysis of the data for copper(I) tetrahydroborate complexes shows that the 11 could not be accurately determined [63].…”

“…The latter also exhibits two resolved or one broad BHterm stretching vibrations at a higher frequency than {M(η 1 -BH4)} (Table 2). Additionally, stretching vibration of CuHBH cycle is a unique feature of {M(η 2 -BH4)} complexes [52,63]. Analysis of the data for copper(I) tetrahydroborate complexes shows that the 11 B NMR chemical shift of the BH4 − group is slightly different for different coordination types (−29.1 ÷ −30.2 ppm for {Cu(η 2 -BH4)} and −30.2 ÷ −40.0 ppm for {Cu(η 1 -BH4)}).…”

“…Thus, the spectral analysis can serve as a base for the initial assignment of the BH4 coordination mode. The X-ray data on the Cu···B distance (vide infra) should allow to unambiguously distinguish the type of BH4 − coordination even if the position of hydrogens could not be accurately determined [63].…”

“…Copper(I) tetrahydroborates with phosphine ligands featuring relative stability to air oxygen and moisture are used as selective reducing agents [36][37][38][39][40], catalysts of photosensitized isomerization of dienes [41][42][43] and hydrolytic dehydrogenation of ammonia borane [44]. Since metal tetrahydroborates have great potential in hydrogen storage technology [45][46][47][48][49][50], as catalysts [51][52][53][54][55] and selective reducing agents [56][57][58][59][60][61] their structural and dynamic properties have been actively investigated [52,[62][63][64]. These studies revealed different modes of BH 4 − coordination to the metal atom, which can behave as mono-, bi-, or tridentate ligand [64].…”