LINKAGE ISOMERISM OF 2 BENZOATO COPPER(I) COMPLEXES CONTAINING BIS(DIPHENYLPHOSPHINO)METHANE BRIDGING LIGANDS - CRYSTAL-STRUCTURES, TSDC MEASUREMENTS AND REACTIVITIES OF [CU2(MU-DPPM)2(O2CPH)2] AND [CU2(MU-DPPM)2(O2CPH)(MU-O2CPH)].H2O

Here we report the molecular structures and reactivities of the two co mplexes [{Cu(O2CPh)dppm}2] (A) and [{Cu(O2CPh)dppm}2].H2O (B), contain ing isomeric dibenzoato copper(I) moieties doubly bridged by dppm liga nds (dppm=bis(diphenylphosphino)methane). In the isomeric unit [{Cu(O2 CPh)dppm}2] of B, the two metal atoms are also bridged by one of the t wo benzoato ligands and a significant shortening of the transannular C u ... Cu distance (2.994(2) angstrom in B versus 3.359(2) angstrom in A) is observed. The eight-membered Cu2P4C2 ring adopts an approximate chair conformation in A and a saddle conformation in B. The structures of A and B have been determined by single crystal X-ray diffraction m ethod. The crystals of A are triclinic, space group P1BAR, with Z = 1 in a unit cell of dimensions a = 11.841(2), b = 11.366(2), c = 10.769( 2) angstrom, a = 100.68(2), beta = 101.45(2) and gamma = 93.37(2)-degr ees. The crystals of B are monoclinic, space group P2(1)/a, with Z=4 i n a unit cell of dimensions a=21.295(3), b = 13.295(2), c = 22.068(3) angstrom and beta = 114.72(2)-degrees. Final R was 0.032 (2553 reflect ions) for A and 0.058 (3909 reflections) for B. Bulky anions react wit h A and B metathetically removing one of the benzoato groups or, when coordinating, both of them. The characteristics of the new anions modu late the conformation of the Cu2(dppm)2 unit. Thermally stimulated dep olarization current (TSDC) measurements have also been performed on B to study the electric polarization phenomena induced by reorientation of dipole moments of the crystallization water molecules in the temper ature range 100 less-than-or-equal-to T less-than-or-equal-to 350 K. T he reorientation ability of the dipole water molecules is probably fav oured by the dynamic disorder of the atoms, which surround the water m olecules in the crystal lattice.