1：Experimental Design and Method Selection:

The synthesis involved heating titanium, selenium, and iodine in a sealed ampule at 250°C for 200 hours. X-ray single-crystal diffractometry was used to determine the crystal structure, and DFT calculations were employed to confirm bonding stability.

2：Sample Selection and Data Sources:

Titanium powder (99.5%), selenium powder (99.99%), and iodine (99%) were used as starting materials. Crystals were washed with ethanol and dried in air.

3：5%), selenium powder (99%), and iodine (99%) were used as starting materials. Crystals were washed with ethanol and dried in air. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment includes a Philips PW 1830/1710 automated diffractometer for XRD, labRAM HR Evolution spectrometer for Raman spectra, FTIR spectrometer VERTEX 80 for IR spectra, Hitachi TM3000 for EDS, NETZSCH TG 209 F1 Iris Thermo Microbalance for TGA, and Bruker APEX Duo diffractometer for single-crystal XRD. Materials include Ti, Se, I2, and glass tubes from Simax.

4：Experimental Procedures and Operational Workflow:

Ti powder was placed in a small tube inside an ampule with Se and I2, evacuated, sealed, heated to 250°C for 2 hours, and held for 200 hours. Crystals formed on ampule walls, were washed with ethanol, and analyzed.

5：Data Analysis Methods:

Data reduction used APEX-II suite, structure solved by direct method and refined with SHELXTL, supported by Olex2 GUI. DFT calculations used BAND 2017 code with LDA and GGA functionals, and QTAIM analysis for bonding nature.