Infrared

Supplementary Material (ESI) for PCCP This journal is © the Owner Societies 2010

photodissociation spectroscopy of Co+(NH3)n and Ni+(NH3)n: preference for tetrahedral or square-planar coordination
Toshitaka Imamura,a Kazuhiko Ohashi,*b Jun Sasaki,a Kazuya Inoue,a Kazuki Furukawa,a Ken Judai,c Nobuyuki Nishic and Hiroshi Sekiyab

Supplementary Information
IR spectra of Co+(NH3)n (n = 4–8) without N2 tagging Fig. S1 displays the IR photodissociation spectra of Co+(NH3)n with n = 4–8. Since the D4

value is larger than the IR photon energy, we preferentially detect a warm subset of the n = 4 ions that have internal energies sufficient to assist the elimination of an NH3 molecule following the IR absorption. As a result, the absorption features of Co+(NH3)4 (Fig. S1a) are

considerably broader than those of Co+(NH3)4·N2 (Fig. 2i).

Co+(NH3)6. The coordination structure of the n = 6 ion is particularly interesting, because Co+Ar6 was found to be anomalously stable,24 and an octahedral coordination was proposed for this ion.22 The experimental IR spectrum of Co+(NH3)6 (Fig. S2a) has a general

resemblance to the n = 5 spectrum. The resemblance makes us suppose that the Co+(NH3)6 ions have 4-coordinated structures that contain Co5IA or Co5IB as a subunit. structures and IR spectra of such (4+2) isomers are given in Fig. S2b–d. The optimized

Co6IA has two

double acceptors in the second shell, whose spectrum is similar to that of Co5IA. Co6IB has two single acceptors, whose spectrum is similar to that of Co5IB. Co6IC has a double and a From our DFT

single acceptor, whose spectrum is a mixture of those of Co5IA and Co5IB.

calculations, the difference in the energies of these (4+2) structures falls within ≈1 kJ mol-1. The experimental spectrum can be reproduced by a superposition of the theoretical spectra of these (4+2) structures.

Supplementary Material (ESI) for PCCP This journal is © the Owner Societies 2010

It is worth examining isomers