Syntheses and Solid State Structures of Tris(pyrazolyl)methane Complexes of Sodium, Potassium, Calcium, and Strontium: Comparison of Structures with Analogous Complexes of Lead(II)

The reaction of NaI with 2 equiv of HC(pz)3 or HC(3,5-Me2pz)3 (pz = pyrazolyl ring) leads to the formation of
{[HC(pz)3]2Na}(I) (1) and {[HC(3,5-Me2pz)3]2Na}(I) (2), respectively. Both compounds have trigonally distorted
octahedral arrangements about the sodium. A similar reaction of KPF6 with HC(3,5-Me2pz)3 results in the formation
of {[HC(3,5-Me2pz)3]2K}(PF6) (3), a complex also shown crystallographically to have a trigonally distorted octahedral
arrangement about the potassium, which is an unusually low coordination number for this large metal ion. The
complex {[HC(pz)3]2Sr}(BF4)2 (4) forms in the reaction of Sr(acac)2 (acac = acetylacetonate) with HBF4·Et2O
followed by 2 equiv of HC(pz)3. The structure is highly distorted, showing κ3 bonding of both tris(pyrazolyl)methane
ligands and, in addition, interactions with the metal from three fluorine atoms from the BF4- counterions. The
symmetrical structure of 1 and the nine-coordinate structure of 4 are both very different from the distorted, six-coordinate structure {[HC(pz)3]2Pb}(BF4)2, indicating that for this compound the lone pair on lead(II) is influencing
the structure. The reaction of M(acac)2 (M = Sr, Ca) with H{B[3,5-(CF3)2C6H3]4} followed by 2 equiv of HC(pz)3
produces {[HC(pz)3]2(Hacac)Sr}{B[3,5-(CF3)2C6H3]4}2(5) (when the reaction is done in CH2Cl2), {[HC(pz)3]2(Me2CO)2Sr}{B[3,5-(CF3)2C6H3]4}2 (6) (when the reaction is done in acetone), and {[HC(pz)3]2(Hacac)Ca}{B[3,5-(CF3)2C6H3]4}2(7), respectively. The structures of all three complexes show a distorted eight-coordinate arrangement
of the ligands about the metal. Crystal data:  1 is orthorhombic, Pnma, a = 16.931(1), b = 22.368(3), c = 7.937(2) Å, α = 90, β = 90, γ = 90°, Z = 4; 2 is trigonal, R3̄, a = 10.7483(8), b = 10.7483(8), c = 35.395(4) Å,
α = 90, β = 90, γ = 120°, Z = 3; 3 is monoclinic, P21/c, a = 9.144(4), b = 13.377(6), c = 15.988(7) Å, α =
90, β = 92.291(10), γ = 90°, Z = 2; 4 is hexagonal, P65, a = 9.42530(10), b = 9.42530(10), c = 55.3713(5)
Å, α = 90, β = 90, γ = 120°, Z = 6; 5 is monoclinic, P2/n, a = 14.1601(3), b = 13.1756(3), c = 27.1826(6)
Å, α = 90, β = 90.1744(7), γ = 90°, Z = 2; 6 is monoclinic, P2/n, a = 14.2709(7), b = 13.2646(7), c =
27.4189(13) Å, α = 90, β = 90.3850(10), γ = 90°, Z = 2; 7 is monoclinic, P2/n, a = 14.2388(2), b = 13.1919(2), c = 26.7879(3) Å, α = 90, β = 90.0650(8), γ = 90°, Z = 2.