Structural systematics of rare earth complexes. XVII Hydrated 1 : 1 adducts of 2,2 ': 6 ',2''-terpyridine with the lanthanoid(III) bromides and somebinuclear hydroxy-bridged dimers

Room-temperature single-crystal X-ray structural characterizations are reco rded for hydrated lanthanoid(III) bromide/2,2':6',2 "-terpyridine (tpy) (1 : 1) complexes, showing all to be ionic and of the form [(tpy)Ln(OH2)(x)]Br -3.yH(2)O, where x and y are 6 and 1 for the isomorphous series Ln = La(-)E r (and intermediate members, by presumption), and 5 and various values for Ln = Tm, Yb, Lu. Crystals of [(tpy)Ln(OH2)(6)]Br-3.H2O are monoclinic, P 2( 1)/c, a approximate to 8.5, b approximate to 18, c approximate to 16.3 Angs trom, beta approximate to 108 degrees, Z = 4; for Ln = La, Er, conventional R values on \F\ were 0.048, 0.080 for N-o 4027, 1347 'observed' (I > 3 sig ma(I)) diffractometer reflections respectively. The complex [(tpy)Tm(OH2)(5 )]Br-3.H2O is monoclinic, P 2(1)/c, a 8.506(4), b 17.376(1), c 15.951(6) An gstrom, beta 106.87(3)degrees, Z = 4, (quasi-)isomorphous with the Ln = La- Er array, R 0.065 for N-o 2067. [(tpy)Yb(OH2)(5)]Br-3.4H(2)O is triclinic, <P(1)over bar>, a 11.902(2), b 11.639(3), c 9.831(2) Angstrom, alpha 98.92( 2), beta 106.84(2), gamma 92.42(2)degrees, Z = 2, R 0.062 for N-o 3422, whi le [(tpy)Lu(OH2)(5)]Br-3.H2O is monoclinic, P 2(1)/n, a 13.635(8), b 9.022( 5), c 19.03(1) Angstrom, beta 99.02(5)degrees, Z = 4, R 0.043 for N-o 3139. Despite a common N(3)LnO(5) coordination sphere in the last three compound s, subtle differences are found in stereochemistry; in the N(3)LnO(6) array , one of the outer water molecules becomes progressively detached as the la nthanoid radius contracts. Some tendency is found toward the end of the lan thanoid series toward the formation of di(hydroxy-bridged) neutral dimers, Ln(OH)Br-2/tpy/H2O(1 : 1 : 8)(x2), [(tpy)(H2O)(3)Ln(mu-OH)(2)Ln(OH2)(3)(tpy )]Br-4.10H(2)O, monoclinic, C 2/c, a approximate to 19.5, b approximate to 14.5, c approximate to 17.1 Angstrom, beta approximate to 92 degrees, Z = 4 dimers, thus far defined by full determinations for the extrema Lu = Er, L u (and Y), R 0.055, 0.043, (0.047) for N-o 3141, 4591, (2991) respectively; the dimer is disposed about a crystallographic 2-axis. An Ln = Dy example, seemingly isomorphous, has also been characterized by cell determination.