Trinuclear nickel clusters, [Ni3(μ3-L)(μ3-I)(μ2-dppm)3]n+ (L = I−, CO, CNCH3, CN-2,6-Me2C6H3, CN-i-C3H7, CN-t-C4H9, CN-n-C4H9, NO+) and the “dimer of trimer” hexanuclear nickel clusters {[Ni3(μ3-I)(μ2-dppm)3]2(μ3,μ3′,η1,η1′- CN-R-NC)}2+, (R = −(CH2)6−, p-C6H4): characterization of large clusters by